correctly adjusting valves


Staff member
this is an area that causes many newer guys problems ,a slight clicking noise at idle in any hydraulic or solid lifter valve train is usually the result of clearances in the valve train, obviously you should have, some clearance, to allow oil flow thru the lifters to provide lubrication on moving parts, in the valve train and a consistent sewing machine like rhythmic clicking from a solid lifter valve train is expected and DESIRABLE. In my experience you can get really darn close adjusting valves on hydraulic lifter engines, while the engines stationary and cold on a non running engine IF YOU know what to look for and how the lash is SUPPOSED to feel but in my experience that takes having done so on dozens of engines before you develop the "FEEL" most guys doing this process the first few times tend to over tighten the rockers, thats why.
the fact is that due to manufacturing tolerances a dot-to-dot install will frequently be a few degrees off! now most guys might never notice, but it can and frequently does effect the engines power band so getting it correct helps and eliminates one potential source of problems (be damn sure you verify the cams degreed in correctly and the ignition firing orders correct and all the distributor wires go to the correct cylinder,s spark plugs and distributor cap locations)

honestly this takes a good deal longer to post about and discuss that to correct and check, so what ever method you might select ,Adjusting the valves is a rather simple procedure, that youll need to go thru on almost any new engine instal and you can use the E-O, I-C method,or if your experienced the adjustments easily done at idle speed, your choice, either works just fine if you know what your doing. I strongly suggest the adjustment to the rocker arms pre- load on the lifters be made with the engine running at idle , where you back off the rocker adjustment nut slowly just to the point the rocker clicks, then slowly turn it in just to the point the clicking stops, then add a 1/4 turn pre-load, obviously this can get messy so a tall valve cover with the top cut out helps reduce oil loss and smoke and if you don,t have that a piece of card board about the length of the cylinder head and about 8"-12" tall placed above the lower valve cover lip , below the rockers can help
Ive always preferred to get the engine temps up to about operational temp levels and adjust the valve train on hydraulics for 1/4 turn in on the rocker nuts from the point they just stop clicking at idle as it tends to maintain the best compromise on both low and high rpm valve train stability.
if you insist on doing it cold the instructions are listed below, you generally turn the engine so each lifters on its matching cam lobes base circle and tighten the rocker slowly while spinning the push-rod between your fingers,any increase in resistance indicated both the lifter and rocker touch and your at zero lash, and then when you feel minimal resistance to rotation indicating theres no effective clearance between lifter and rocker,so you add 1/4 turn,lifter pre-load, that puts it close.
its back the rocker adjustment nut out until the rockers clattering /clicking, then slowly turn it in the nut too just the point, the noise stops than add 1/4-1/2 turn of preload, the engine will stutter for about 5-10 seconds,as the lifter preload adjusts then stabilize

btw it is usually far easier to hear each rocker change sound,the second time you go thru,the adjustment, as the other rockers will generally be far less noisy

If you insist on adjusting the lifter pre-load on a new engine cold and experience a cam lobe or lifter failure after a few hundred miles, its frequently the result of incorrect lubrication or valve train clearances or geometry issues causing that most of the time, if so chances are EXCELLENT you've wiped a cam lobe, because in my experience maybe 1 out of 40 guys has the experience to do this correctly by feel alone. the valve adjustment done at idle is FAR less likely to get your into problems
yes theres a hundred guys who are about to post Im wrong and many of those same guys are the same guys that have unexplained cam failures or bitch, about soft or defective cams, the truth is that hydraulic lifters require a certain amount of clearance to function and allow the valve train to live and it takes some skill to get that clearance set correctly. IF you insist on doing the valve adjustment on a non-running engine,mark the harmonic balancer every 90 degrees starting at the timing mark,on the damper aligned with the timing tab at TDC. put the engine on #1 TDC on the compression stroke and adjust both rockers with both valves closed, then rotate the engine 90 degrees clockwise as viewed from the front and set both valves on #8. Proceed in this fashion through the firing order until you have them all set (18436572). guesswork will get you into trouble
your free to do things any way you want too, but I see far more guys with valve train issues among the guys that adjust valves cold in a non-running engine, or fail to check clearances during the assembly process, or who assume they get the adjustment correct than those who adjust the valves at idle, and guys who take the time to verify clearances and valve train geometry, and check push rod
length . MOST flat tappet cams are designed for FAIRLY low spring pressures and have cam lobes that are cut at an angle to allow the lifter to spin, failure to provide the required clearance retards the lifters ability to spin in the lifter bore , causing rapid wear, and cam core, don,t get the necessary lubrication, results in a ruined cam and lifters


if your trying to reduce oil spray from getting on the exhaust manifolds while adjusting the valves/rockers, as the engine idles, you have options , you can cut a 10" tall and 22" wide section of cardboard , or thin flexible aluminum, sheet metal, to stick in between the lower outside block valve cover gasket rail and rockers, too deflect oil while, inspecting or adjusting the rockers or you can modify and old valve cover

the the tall cast valve covers I fabricated/modified for valve adjustment is taller and has a smaller open area,
but yes the basic concept of having a valve cover modified to adjust valves at idle works very effectively,
watch video
I bought a used set like these to modify and drilled 8 -2 1/8" diameter round holes centered on the rocker studs (yes the holes overlap)





watch this video, it depicts the lifters movement as the cam lobe rotates under its base forcing it up as the lobes ramp, rotates under the lifter base,removing the clearance slack,
as it compresses the valve spring and forces the trapped oil, up the push rod and lifts the valve

If you are concerned with measuring the clearance in the hydraulic lifter seat when selecting and measuring the correct valve train geometry,
so you can order the correct length push rods...
I don,t think you have the correct idea as to how hydraulic lifters work,
yes it is possible for an engine with hydraulic lifters to be pushed too operate at a high enough rpm that the time required for the lifter seat to fully depress and all the oil too be forced up to the push rod/rockers , to be so short that the lifter pumps up and the valves will have less seat time, ( sometimes one of several factors, like the lifter leaving the cam lobes surface as the inertial loads exceed the valve springs ability to maintain lifter too lobe contact, referred too or contributing to what is commonly referred too as valve float) but that has ZERO to do with selecting push rod length or proper valve train geometry, (remember at 6000 rpm the valve is lifted off its seat 50 times PER SECOND)

look thru yard sales and try hard too find a TALL valve cover, preferably a tall cast aluminum valve cover ,something like these below

unlike this short steel version posted above and mill the center top center surface in a similar manor to this and you have a very useful tool to use to adjust valves without getting much oil on the headers

standard OEM rocker nuts like these can get loose and not retain the proper clearances, as vibration allows them to slowly back off

rocker stud jam nuts with a locking center jam stud are less likely to loosen



I always get asked if you can pre-load the lifters before you run the engine, and the answer is yes, it can be done but your very unlikely to get it exactly correct, youll be close, if you have experience, doing it, and theres easily about .060 adjustment slack in the lifter seal, so if your happy being close, yes its done all the time!
hydraulic lifters BY DESIGN, leak oil both up the push rod to supply oil flow to the rockers and past the push rod seat to allow for pressure and clearance equalization, it really won,t matter much if you set the lifter adjustment on a hydraulic lifter while the engine idles, as oil will be flowing into the lifter while the lifter is on the cams base circles and up thru the push rods as the lobe rotation compresses the valve spring, forcing oil and any trapped air up out of the lifter.
yes you can set lifter pre-load with experience while the engines cold, but in my experience the chances of doing it correctly if your rather new to the process is low.
if you set the lifters on a non-running engine you may find that you need to go back and do it again once the engines been run awhile, this is almost mandatory in my experience.
that knock sensor myth, youll occasionally hear about that says roller rockers can,t be used because the computers knock sensor won,t allow roller rockers, on the Lt1 and LT4 engines, got started because many people can,t correctly adjust valves, especially if your using roller rockers
they leave too much slack in the valve train (usually due to adjusting the valve train while its cold and not adjusting the hydraulic lifter pre-load correctly) and as a result the slight ticking that results is detected as detonation.
once correctly adjusted theres no need to swap knock sensors





solid lifters can be adjusted in a similar manor, you just don,t add any pre-load once you feel resistance to the push-rod rotation and you adjust each valve with the recommended cam lash clearance gauge, listed on your cam card temporarily inserted between the rocker and tip of the valve stem, if your really looking for max performance a correctly set up and adjusted solid lifter valve train almost always has at least a 600rpm-1500rpm advantage, as it will allow higher rpms before valve float, or loss of valve control



To cold adjust pre-load on hydraulic lifter camshafts with
adjustable rocker arms, turn the engine in the normal direction
of rotation until the exhaust lifter starts to move up, then
adjust the intake valve to zero lash with no preload, then 1/4
to 1/2 turn more max. Turn the engine over again until the intake
opens completely and then is almost all the way back down.
Now, set the exhaust valve to zero lash, then 1/4 to 1/2 turn max
more. Continue the above procedure for each cylinder until
all valves are adjusted to the same amount of preload. This
procedure will give you the correct lifter preload for any
hydraulic lifter cam with adjustable rocker arms.



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but on a hydraulic lifter, that clearance is rapidly filled with pressurized oil under a lifter/push-rod seat, that moves to take up slack as the cam lobe , rotates under the lifters base and compresses the lifter seat, which forces oil up the push-rod to the rocker, and lifts the lifter,rocker,and valve , so you'll need to verified all valve train clearances and geometry during the pre-assembly stage of your engine build up, and made sure theres no clearance issues,a bit to much tightening on the rocker nut will prevent the valve from seating, youll have very low compression or zero compression, a bit to little results in a noisy loose valve train READ THRU THE LINKED INFO ... g-149.html

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its the attention to details and checking clearance etc. and time and care taken,
that makes the difference between a barely or average functional ,
and a rather exceptional engine build, yes the urge to get it running is strong,
but getting it done correctly is the goal


keep in mind some roller lifters (even hydraulic roller lifters)and roller rocker combos will by design have a good deal more slack , to provide good lubrication and oil cooling or clearance to the roller bearings than a similar combo using different components and the way you set up or preload the valve train will effect your resulting noise levels, a soft rhythmic clicking even with hydraulic lifters, is common with many designs of roller rockers , this soft rhythmic clicking,is NORMAL, and you'll learn to appreciate the soft rhythmic sounds a bit similar,to and sounding like a sewing machine or a bit softer than properly adjusted solid lifters, and you will defiantly hear a difference in the sound if your adjusting them at idle as the preload reaches zero lash if you slowly tighten up the rocker adjustment nuts ,allowing the valve train time to bleed off the oil under the lifter seats , that are taking up the valve train clearance as you approach zero lash , but naturally an experienced ear helps
1/4-about ideal -1/2 max turn in past the point where they just stop clicking at idle,is MORE than enough to set the proper preload (hydraulics), obviously solid lifters don,t require (PRELOAD)they require clearance or (LASH) that's usually specified on the cam manufacturers cam card.
if you don,t have the specs start with .020 on the intake valves and .022 on the exhaust thats close for most solid roller lifter cams

I have no idea why people are so afraid to adjust valve lash on solid lifter cams, its just not that difficult to do,
adjusting a solid lifter cams a bit like SEX, your nervous the first few times, but after gaining some experience you learn what to do, how to do it correctly and learn to enjoy it

if its a street, solid lifter cam design, it will tend to go significantly longer between adjustments ,than a more aggressive race only cam lobe design with less emphasis on long term durability, than on max horsepower. but the answer depends on the cam lobe design used and valve train components,and the mileage,your putting on the engine and at what average rpm levels, higher stress levels tend to make adjustments more frequent but adjusting valves every few weeks, on the more radical designs to having several months between adjustments on the milder cam designs is about average in my opinion, Ive run mostly solid lifter flat tappet design cams for years in most Mopar and G.M. (Chevy,Pontiac, Caddy) engines
in most cases it takes longer to remove and replace the valve covers that it does for the actual valve adjustment on a solid lifter cam, if you've got the correct tools and a bit of experience, personally I prefer to do it with a tappet gauge at idle but both methods work
in 99.99% of the cases I see guys having problems like a rough idle or loss of compression from badly adjusted valves its the direct result of guys who have no idea how to adjust valves and refuse to do it correctly , and as far as IM concerned youll NEVER EVER get it exactly correct doing it cold on a non-running engine,most guys get the rockers too tight, I don,t know why theres such an aversion to doing it at idle I don,t know why because its simple to do with a properly modified tall valve cover cut to significantly reduce oil leakage during the process and on flat tappet hydraulic cams its just backing the rocker out off the rocker stud threads till it clicks loudly then slowly and carefully tightening it untill the clicking just stops and then adding a 1/4" turn of preload and locking the adjustment


this is a short valve cover modified to do valve adjustments without about 80% of the mess that you get without using a valve cover thats so modified to reduce oil spray, a tall cast aluminum cover works even better if modified in a similar manor, IF you can find TALL CAST ALUMINUM VALVE COVERS like those pictured below , and have the center milled out to provide easy access to the valve train while leaving about an inch overhang around the perimeter youll have the best tool


you can do the adjustment at idle or if your dampers marked every 90 degrees you can do it static, but Ive never seen it done static on a cold engine and getting it 100% correct! ... g-149.html

ok how do i adjust them now?

(Ive always found the final adjusting of HYDRAULIC LIFTERS, OR SOLID LIFTERS is best done at idle, with the engine up to operating temps., as it allows for all the variables like heat expansion and lifter seat movement as the oil pressure lifts the push rod seat)but with solid lifters that takes a great deal of experience, so the static cold adjustment methods are generally preferred,by most guys.....LINKED INFO POSTED BELOW
ID ALSO POINT OUT THAT,The most commonly accepted method of adjusting the rockers with solid lifters and ensuring the lifter is centered on the cam lobe base circle is the EOIC (engine off) method. For each individual cylinder you adjust the intake rocker when the exhaust valve just starts to open. You adjust the exhaust rocker when the intake valve is fully open and just starts to close.


Valve Adjustment: ENGINE OFF!

with #1 cylinder Intake Valve at full valve lift .... Adjust #6 Intake Valve
with #8 cylinder Intake Valve at full valve lift .... Adjust #5 Intake Valve
with #4 cylinder Intake Valve at full valve lift .... Adjust #7 Intake Valve
with #3 cylinder Intake Valve at full valve lift .... Adjust #2 Intake Valve
with #6 cylinder Intake Valve at full valve lift .... Adjust #1 Intake Valve
with #5 cylinder Intake Valve at full valve lift .... Adjust #8 Intake Valve
with #7 cylinder Intake Valve at full valve lift .... Adjust #4 Intake Valve
with #2 cylinder Intake Valve at full valve lift .... Adjust #3 Intake Valve

Exhaust Valve Adjustment: ENGINE OFF!

If you have noticed, this is the same procedure as the intake valves listed above, just that you are now adjusting the exhaust valves the same way.

with #1 cylinder Exhaust Valve at full valve lift .... Adjust #6 Exhaust Valve
with #8 cylinder Exhaust Valve at full valve lift .... Adjust #5 Exhaust Valve
with #4 cylinder Exhaust Valve at full valve lift .... Adjust #7 Exhaust Valve
with #3 cylinder Exhaust Valve at full valve lift .... Adjust #2 Exhaust Valve
with #6 cylinder Exhaust Valve at full valve lift .... Adjust #1 Exhaust Valve
with #5 cylinder Exhaust Valve at full valve lift .... Adjust #8 Exhaust Valve
with #7 cylinder Exhaust Valve at full valve lift .... Adjust #4 Exhaust Valve
with #2 cylinder Exhaust Valve at full valve lift .... Adjust #3 Exhaust Valve

any time you adjust new lifters without oil pressure and heat expansion taken into account like in a running engine you'll have problems, yes you can get very close but IVE always found a final adjustment made while the engine idles to give the most consistent results.
yes its potentially messy unless you have an old tall valve cover with the top surface slotted for rocker access to limit oil splash on the headers but if done correctly you get consistent results




viewtopic.php?f=78&t=631&p=845#p845 ... tips1.html ... -2076.html ... NST150.pdf ... re=related ... index.html

btw if your totally new at this the tappet feeler gauge measures the lash clearance between the valve and rocker on solid lifter cams

Ive generally found the most consistent and best results , if you warm the engine up to operational temps,
back off the rocker adjustment nut slowly just to the point the rocker clicks at idle, very slowly tighten,
just to the point the clicking stops and then add 1/2 or 3/4 of a turn and lock the jam nut.
in many engines youll find that when you first restart that engine its going to have a valve train click,
or two for the first 60- 1min-.45 seconds, but that stops as soon as the oil pressure stabilized so its of zero concern.
btw I also really like the appearance of the M/T valve covers, and
I generally find a valve train stabilization girdle a P.I.T.A. to use,
but well worth the extra effort.
obviously its critical you check all clearance issues

shaft rockers vs rocker stud girdles

always call the cylinder head manufacturer for their input on rocker stud girdles,BEFORE PURCHASING THEM< because rocker stud spacing, and stud angles can vary, between head designs and models READ THRU THIS THREAD ALSO its not horsepower, its the stress on the valve train, that makes a...


work with all rocker designs or all jam nut designs or fit under all valve covers






I just don,t think adjusting the valves without the oil pressure and the block up to operating temp. is the best way to adjust valves , but yes you can do it just fine with several methods described above

how do you adjust valves at idle without the mess of oil getting all over the engine and headers


you simply cut the ribbed center section out of the valve cover, and glue the synthetic valve cover gaskets on them in the normal location,
when you go to adjust the valves you first remove the standard valve covers and install your VALVE ADJUSTMENT COVERS, they retain about 80%-90% of the oil that would normally be lost over the edge of the cylinder head while adjusting a running engine, they also catch much of the splashed oil, just leave a 1/4"-3/8" of the rolled top for strength around the perimeter of the top surface. I bought my set for $10, they were old and slightly discolored but I could not care less! I took them home and used a drill and saber saw to remove the center ribbed area, theres several brands that are very similar in appearance, all will work! and Ive used them for over 25 years, if I remember correctly they are mickey Thompson brand

now if the lifters are hydraulic of course you just back the adjustment nuts off the rocker studs with a wrench, slowly until the rocker JUST starts clicking , then slowly tighten the nut just up to the point that the clicking stops then add 1/4 to 3/8 turn to preload the lifter and move to the next rocker and repeat, the only difference with solid lifters is you use a feeler gauge inserted between the valve tip and rocker after they click slightly,to measure the lash distance recommended on the cam spec. card (normally .016-.028 thousands) and you tighten them just to the point at idle that the clicking stops... then you remove the feeler gauge and move to the next rocker
if your using jam nuts don't forget to lock the Allen key



IF you don,t think lifter adjustment matters to engine operation, I don,t think you have a firm grasp on whats going on,during the mechanics of the lifters operation, the lifter seat is FULLY compressed to its seat as the cam lobe ramp spinning under the lifter base lifts the lifter off the cams base circle,and the lifters push-rod seat is compressed against the valve spring, oil trapped between the lifter, is forced up the push-rod until the lifters push-rod seat reaches its fully depressed location in the lifter body, this takes time and depending on the rpm levels it may not reach its full depressed seat location in the lifter body before peak valve lift, keep in mind that at 6000rpm the lifter is cycling from seated to fully open 50 times a second.
the lifter seat is forced back to its full upper location by a combo of engine oil hydraulic pressure and a small spring, this also takes time, hydraulic lifters will at some point in the upper rpm band fail to fully cycle, but generally continue to cycle once the rpms drop again.
the factory suggests 3/4 turn as it allows more compensation for wear in the valve train, and anything from 1/4-3/4 works but you get more valve spring cooling with 1/4

or if your really lazy (you can use this method on hydraulic lifters)install the tall cut valve covers and just turn the engine about 45 degrees or 1/8th turn,(start anywhere )and take the slack out of any loose rockers, repeat for 720 degrees,(twice around) then go back and give each rocker nut one turn OUT(LOOSER) and start the engine,(yeah it will be messy and noisy) and then go back and turn each rocker IN (TIGHTER) until it just quits clicking plus 1/4 -1/3rd of a turn past that point BTW many Chevy rocker studs use a thread pitch of about .040 thousands per turn so once your very familiar with your solid lifter engines needs and the cam lash clearance you need and once you verify the pitch rate of the threads you can adjust solids surprisingly close to correctly by running them in till they quit clicking, then OUT about 1/3-1/2 a turn to get the correct lash rather than IN like on a hydraulic lifter to add pre-load,naturally you'll need to verify with a feeler gauge.Id suggest two quick checks first, replace your oil filter, as they can be defective and block oil flow, and while its off, inspect the spin on oil filter adapter plate, to verify its not busted


and then verify your oil levels at the correct level on the dipstick,
then loosen ALL the rocker arms until they are loose enough to click at idle,
did you do what I suggested and loosen every rocker until it clicks, the reason is that its entirely possible to cold adjust rockers so the lifter seat can,t move far enough up to fill the lifter with oil,when its on the base of the cam lobe when the rockers not placing spring loads on the lifter seat so that no or darn little oil gets under the push rod seat consequentially, no-or very little oil moves up the push rods

NATURALLY you need to know the threads per inch on the rocker studs and a quick check with your calculator will give you the necessary info on the clearance a full turn of the adjustment nut advances or loosens the rocker, and be aware that this is not exact but a fast way to get close at the track

you can set the lifter pre-load cold and get very close, to the ideal lash/pre-load, but IVE always found that adjusting the valve train once the engines up to operating temps at idle gives the best results

having the correct tool if your using jam nuts with locking Allen keys helps
experience, judgment and practice helps, especially with locking rocker nuts and rocker girdles

you generally back out the locking Allen key in the center and adjust the rockers just like you normally would do, ,once the nuts adjusted correctly with a 1/4 turn past the point where the rocker stops clicking on hydraulic lifters or at the correct lash with solids using a tappet gauge you use the t-handle Allen key to lock the nut in place, but you ll eventually find they occasionally tend to loosen over time so the proper cure is to run the center Allen key in, until its solid, against the top of the stud the nuts locked on, then loose the nut about 1/10-1/8 turn, re-seat the locking center stud and then turn the loose the nut in again about 1/10-1/8 turn, back to its original location, this will preload the center lock nut, stud, and lock nut threads,a couple thousands assuring a firm seat and the nuts won,t back off.



the method below, is simple and quick,it gets you very close, but in my experience its MANDATORY to readjust at idle to get it correct
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Ive tried all the methods listed above.....but I keep coming back the the first method Ive used for 40 years...if you have excessive valve train noise , from a hydraulic cam ,either flat tappet OR HYDRAULIC ROLLER CAM,its the result of clearance issues or improper adjustment,
if you don,t think lifter adjustment matters your miss informed, the rpms and spring pressures and cam lobe acceleration rates effect function,
I don,t think you have a firm grasp on whats going on,during the mechanics of the lifters operation, the lifter seat is FULLY compressed to its seat as the cam lobe ramp spinning under the lifter base lifts the lifter off the cams base circle,and the lifters push-rod seat is compressed against the valve spring, oil trapped between the lifter, is forced up the push-rod until the lifters push-rod seat reaches its fully depressed location in the lifter body, this takes time and depending on the rpm levels it may not reach its full depressed seat location in the lifter body before peak valve lift, keep in mind that at 6000rpm the lifter is cycling from seated to fully open 50 times a second.
the lifter seat is forced back to its full upper location by a combo of engine oil hydraulic pressure and a small spring, this also takes time, hydraulic lifters will at some point in the upper rpm band fail to fully cycle, but generally continue to cycle once the rpms drop again.
Ive probably been thru this several hundred times,if your not having a clearance or valve train geometry issue, thats causing the valve train noise, its related to improper adjustment, you simply can not get the hydraulic lifters properly adjusted doing it cold & static, you can get it darn close but not exact, but until you do it many guys won,t believe it,your solution...
adjust the rockers at idle just like you would with a flat tappet hydraulic cam and you'll reduce the valve train noise level significantly, just back off each rocker nut until theres a noticeable click then SLOWLY tighten just to the point it stops clicking then add a 1/4 turn, and lock the nuts



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I may be old school,but IVE never had a problem adjusting solid lifters, that way either the difference is you use a tappet gauge inserted between the rocker and valve tip during the process and I will continue to do so with this method,simply because ITS PROVEN TO WORK, keep in mind, I set my lash with a feeler tappet gauge at engine idle speeds, by backing the rocker nut off a bit on the rocker stud until the rocker clicks and I can slide the tappet gauge between the rocker and valve tip, then tighten it at idle just to the point the clicking stops then I remove the tappet gauge
essentially the methods similar to the way I set hydraulic lifters, but on hydraulics you don,t use a feeler/tappet gauge and once the rocker nuts tightened to the point the rocker stops clicking you add an traditional 1/4 turn for pre-load ... ppets.html

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next time your looking for a feeler gauge to set valve lash clearance,
for some reason most auto parts stores don,t seem to have feeler gauges but do have (TAPPET GAUGES) ... map=27994G

standard hydraulic lifter

IT should be obvious that you'll need to pre-prime the blocks oil passages and adjust the rockers so oil flows from the rockers with the engine being pre-primed with a priming tool being used BEFORE trying to start any engine with a new cam to insure oil flow begins instantly on the engines start-up,you WON,T get oil to all lifters equally unless the engines crank & cam are spinning,(so during testing spin the engine slowly with a breaker bar or ratchet), because the oil passages feeding the lifters aligns differently at different lifts,your oil leak at the distributor base is normal, but the clearances and flow may be excessive, with a priming tool, some are not nearly to spec. ID measure the diam. of the oil pump primer and then measure the distributor base, Id bet the distributor base is larger and fits better, which reduces the potential for leakage.

those bottom two bands form a wall on the oil passage, some guys cut a rounded grove and install an O-RING so the upper band seals too the block, you don,t want to do that to the lower band simply because that's the oil flow source to the distributor /cam gear
20 psi is about normal for your typical 3/8 drill,max pressure is not nearly as important as checking flow, and for leaks where there should not be leaks, with an engine primer tool,Ive brazed a socket to the top of my oil pump primer and use the 1/2" drive air ratchet to drive it, it won,t heat up and burn up like a electric drill will.
don,t get alarmed if you get zero pressure or flow for a few seconds,(the oil filter and passages need to fill first) that's one reason WHY your pre-priming, to get oil flow to the bearings instantly on start up , you don,t want them running without oil flow if you can prevent it even for 20 seconds
be very sure you check all the valve train clearances, having a rocker bind on a rocker stud can easily result in busted rockers or studs or bent pushrods


it should be obvious that the slot clearance in some rockers , especially with poly locks significantly limits rocker movement before clearances become an issue


tappet adjustment_zps8vi9yxmu.jpg

Here is what AFR says about valve lash for their heads.

"Be aware that an aluminum headed/iron block combination usually requires approximately .006 tighter lash when it is cold. An all aluminum engine could be as much as .010-.020 tighter when the motor is cold. Every motor is different, but these guidelines should get you in the ballpark."
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one little known bit of engine trivia, the thread pitch on the rocker studs is a known value, and therefore you can use that info to get a close approximate lash clearance.

ok, HOW you ask?
if the rocker studs have a comon NF thread theres a pitch or number of threads per inch, now obviously youll need to carefully verify what the thread pitch, and the clearances are with a feeler gauge on your engine, while its not running and take into account the rocker ratio but lets assume
3/8" 24 Threads Per Inch
7/16" 20 Threads Per Inch
Threads per Inch Distance per 1/4 of a Full Turn
24 .0104â€
28 .0089â€
32 .0078â€
36 .0068â€
40 .0063â€

from that you can adjust the rockers remarkably close to thier correct lash value in a similar manor to that used for hydraulic lifters , but instead of adding preload by running the rocker nut in slowly just to the point the lifter stops clicking at idle, then adding a 1/2 turn to add preload, you run the rocker in slowly at idle just to the point it stops clicking and BACK IT OUT the approximate lash distance, using the known thread pitch as a guide.
lets say the lash should be .016-.018
youve got a 3/8" stud with 24 threads per inch, with a bit of math we find that each full rotation of the rocker nut advances or reverses the nut .041 time 1.5 (or your rocker ratio),per inch, so youll get the approximate lash with backing the nut off about 2/5ths of a full turn, or a bit less than 1/2 turn but more than 3/4rs of a 1/2 turn
naturally youll have verified exactly what your engine requires before doing this, so youve got the correct math and value
yeah! I know your thinking its not exact! well from YEARS of doing it I can tell you that after awhile youll get a feel for the engines sound and responce and youll find that you can get very good results

this infos very handy with self alighing rockers that make setting lash with a feeler gauge a P.I.T.A.



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Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip

Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.

Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.

one of the most common screw-ups guys make is to over tighten the rocker arm adjustment, honestly I see that so often its almost mandatory that I check the valve lash or preload on every tune-up, it seems that there must be some law Ive never heard of that states failure to over tighten rockers on new engines or cam replacements results in mandatory instant castration.
if you adjust rocker pre-load to only a 1/4 turn past the point the rockers just stop clicking at idle you'll generally have plenty of oil flow , remember the more you pre-load the rocker the less the push-rod seat can move and the lower the rate of oil flow pushed thru the push-rod as the cam lobe compresses the trapped oil under the push rod seat, keep in mind both rocker lubrication and valve spring cooling depend on constant oil flow rates

ID also point out that drilling a small (.031) diam. hole in the pass side oil passage plug behind the cam timing gear allows any trapped air in the oil passages to bleed out far faster so you get oil to the rockers much faster

this method helps during engine assembly but requires two full rotations
(720 degrees on the engine, notice no spark plugs installed to allow easier rotation)

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IF YOUR HAVING trouble with rockers and poly locks coming loose with solid flat tappet lifters.....Ill assume youve verified the rockers and cam & lifters and valve train are in good condition theres no worn cam lobes etc, and you know your clearances are correct before you start,
once adjusted correctly poly locks don,t generally come loose and in most cases solid lifter flat tappet cams only need ocasional adjustments, by occasional Id say it depends on the components but several THOUSAND miles between adjustments at the MINIMUM and Ive seen lots of flat tappet engines go 10K between adjustmens or even more.

ok , now IM old school but I get excellent results and Im not big on making things complicated, back off the rockers at idle till they click, slip a tappet feeler gauge of about .002-.003 larger than the manufacturers recommended lash,

(btw tappet gauges are cheap and expendable and its comon to have them bend and need replacement)
between the rocker and valve stem and tighten carefully till the clicking stops with the poly lock then lock the set screw, once your done with all 16 , go back and give each poly lock about a 1/10-1/8 turn tighter, to lock the set screws firmly,(this takes up the slight extra clearance and locks the poly locks firmly) keep in mind the rockers wont move in that far as slack in the threads is being compensated for as the nuts lock to the studs and compress the lock screw


if you read carefully , the post above, youll see I said if the ideal lash is .016 you use a .019 tappet gauge and once adjusted with the clicking at idle method, you turn in the center set screw and then turn in the poly lock about 1/10 turn further to lock it firmly thus you have very close to the desired .016 lash as the threads generally move the rocker about .040 per full rotation., and youve remove all slack, preloading the threads a bit, keep in mind the exact clearance, being a thousandth off or exactly correct is not as critical as being consistent


thats really simple, the seat in a hydraulic lifter rides on a cushion of pressurized oil, oil that's displaced up the push-rods as the cam lobe sweeps under the lifter base, as the lifter returns to the cam lobes base circle the lifters seat is pushed back up to full height by oil pressure (one reason lifters tend to click with low oil pressure)
the potential problem is that the total distance the seat supporting the pushrod moves is usually about .055 thousands, a full turn on a rocker nut is usually .040, so the more you preload the lifter the lower the volume of oil under the lifter seat

picture may help

BTW roller lifters are very similar just with a roller wheel added to the base






most of the GIVE or clearance or movement in a hydraulic lifter push rod seat is the result of pressurized oil flowing into and lifting the push rod seat, without the pressurized oil entering the lifter body,from the sides of the lifter body from the oil passages in the block, manually forcing the push rod seat down into the lifter body is basically a one shot deal that generally only going to compress in a minimal .060 -.08 once until oil pressure forces the seat back up.
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a few things you should know, if your useing the perimeter design valve covers

Ive had the best luck with the extra thick synthetic /cork composite mix gaskets

[1] synthetic oil desolves that yellow 3m weatherstrip gasket adhesive than many guys use over a few months time so you cant use it to glue valve cover gaskets

[2]you must use a o2 safe gasket cement like the BLACK RTV silicone cement and you must clean and degrease the cover with acetone or a similar solvent before glueing on the gasket to get the best retention

[3]you need to allow at least a few hours to over night,depends mostly on temp. for that black silicone gasket cement to set up before installing the valve covers, and placeing them gasket side down on a table with a sheet of wax paper under them and a 20lb weight on top of each valve cover while the cement sets up is the best way to insure the gaskets stay correctly aligned on the valve covers perimeter

[4]a light coat of (PAM) cooking spray on the lower gasket surface keeps them from sticking to the cylinder heads after installation

[5] these gasket retaining rings add a great deal to the valve covers ability to firmly hold the gasket WITHOUT bending SHEET METAL VALVE COVERS OR CRACKING CAST ALUMINUM VALVE COVERS AND ARE WELL WORTH THE MINIMAL COST


[6]doing it correctly the first time saves time and money

Adjusting Hydraulic Lifters for Proper Preload on a non running engine with hydraulic lifters

Since hydraulic lifters can compensate for thermal expansion of the engine, the adjustments can be made with the engine cold; hot adjustment is not necessary.

In order to adjust the preload the lifter must be properly located on the base circle or “Heel” of the lobe. At this position the valve is closed and there is no lift taking place.You will need to watch the movement of the valves to determine which lifter is properly positioned for adjusting.

1. Remove the valve covers, and pick a cylinder you are going to set the preload on.

2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder.When the exhaust valve begins to open, stop and adjust that cylinder’s intake rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)

3. Back off the intake rocker arm adjuster and remove any tension from the pushrod.Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)

4. Now spin the intake pushrod with your fingers while tightening down the rocker arm.When you feel a slight resistance to the turning of the pushrod, you are at “Zero Lash”. Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position. The intake is now adjusted properly.

5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close.When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.

6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.

Tech Tip courtesy of Crane Cams
the LASH/PRELOAD on a lifter determines several things and one of those is the volume of oil forced up the push rod and the valves ability to bleed off heat to the heads thru the seat contact.
minimizing the pre-load allows slightly longer valve seat contact and greater oil flow to the valve train and less likely hood of burnt valves.
the oil trapped under the pushover seat in the lifter supports the push rod and can,t be compressed easily , the total distance for pre-load adjustment most lifter seats have available is in the .060 range, if you minimize the pre-load the oil reaching the valve train as the seat collapses and forces it up the push rods increased, as the lobe spins under the lifter, total valve lift may be very slightly effected , but Ive always preferred durability over trying for the last possible bit of peak power.
keep in mind , that clearance is set on a relatively cool engine, once you start running it hard the temp. increases rapidly and that lifter and valve train expand due to heat, minimal valve train clearances, and limited oil flow to cool the springs might become a problem, especially when you realize that about 40% of the engine heat comes not from combustion but from the valve train and springs, and friction, valve springs glow red hot and fail in under 5 minutes at 6000rpm with no oil flow to cool them according to SMOKEY YUNICKS TESTING.
you also must keep in mind that as the rpms increase the TIME available for the lifter to bleed off oil under the lifter seat decreases rapidly, resulting in slightly higher effective lift at the valve.
you might want to keep in mind valve pre-loads usually set while the engines not nearly as hot and the expansion, of the components due too heat is minimal compared to the conditions during a race, where extra clearances may be necessary in the valve train once everything reaches true operational heat levels.

if you need to adjust solids more than about once every 3-4 months, after the first month, you've probably have valve train geometry , wear or clearance issues.
On my old big block camaro with a 496 and on my corvette with a BBC 496 , I can,t remember ever needing to adjust the valve train after the first two weeks, now being the type of guy I am I did adjust it as part of the maintenance procedures when I changed oil, but that proved to be an un-needed waste of time as they didn,t need it, and went back exactly as before

keep in mind I groove the lower 1/3rd of my left lifter bores so I have good oil to the lifter/lobe contact areas, and used quality roller rockers, and a quick check with a tappet gauge proved all that was generally required.
Id point out that they make solid lifters with small oil spray holes in their base that will do the same thing with zero machine work,


and you can place a standard solid lifter on a sheet of 600 grit wet sand paper on a sheet of glass and quickly sand a small flat surface along the lower side that will allow increased oil flow

why is everyone so darned reluctant to set or finely tweak the valve pre-load, by simply being old school and adjusting the valves at idle, with the engine up to temp, once the cams broken in correctly?
yes Ill freely admit its a bit messy (especially if you don,t have a tall valve cover with the top cut out for access during the process) and yes if you have the correct tools its far LESS messy but it does give consistent results if your even semi skilled!

there's several ways to set the valves cold with a non-running engine, during the assembly stage,but even thought IVE used all of them at one time or another I always find that adjusting the valves at idle with the engine up to running temp with specially modified valve covers to limit the oil splash loss gives the most satisfactory results
IN about 99% of the Chevy sbc & BBC engines I work on, if you cant get the valves running really smooth with that adjustment at idle method there's some clearance or wear issue that needs to be addressed, and no valve adjustment alone will clear up the valve train noise issue, and yes go back and check yourself you'll find it results in a very consistent & stable valve train

it really helps to find a tall scrap valve cover and modify it like this, a tall cast cover works best at keeping most of the oil from getting all over the place


you simply get the engine to idle, back off each rocker slowly until it clicks at idle, then very slowly take up the slack just till the clicking stops, at that point add 1/4 turn and lock it in place...don,t forget the valve cover gasket and bolting it into place during the procedure
those look similar to mine but I used some tall cast covers
they are a GREAT ASSET

IF your valve cover cracked, or leaks its generally the result of improper gaskets, installation or over tightening the bolts because of un-equal clamp loads on the bolts, it can be still used with these hold down rings that distribute the clamp loads and it can be fixed with J&B weld EPOXY, steel covers bend and leak, cast covers tend to crack, both problems can be far less likely to happen if you use the chrome hold down rings or at least the other little washers

yes you can adjust roller rockers at idle, yes there will be some oil spray,
(generally less than stamped rockers)
but if you make a custom valve adjustment valve cover, to minimize oil splash, for the job, its minimal
if you have the clearance a tall cast aluminum valve cover makes the best start point

yard sales and swap meets are good sources, and since you only need one a damaged set that sells dirt cheap with one damaged valve covers a great deal

yes adding a quart of MARVEL MYSTERY OIL

will tend to free up stuck lifters, but it won,t cure all potential issues

if you find one or a couple rockers are not flowing oil at idle,
first step,
Id suggest you back off the rocker nut on that push rod, pull that push rod and flush it out internally,
with carburetor cleaner or gasoline,just like is usually done before a new cams installed too limit the potential abrasive micro-crap in the engine,from any previous issues.
if any engine shows signs of having sludge build-up or a cam, or bearings, or lifters, have previously failed, you'll need to carefully clean all of the internal parts, before re-use.
In most cases you would soak the rockers and push rods in gas over night and use an air compressor too blow out the push rod internal passages, soak the push rods for several hours in gasoline, then, run some pipe cleaners through it, to be sure its totally clean and free of internal sludge and debris, like anyone should have done with all the push-rods, prior to assembly.
Id suggest you back off the rocker nut on that push rod adjustment slowly too the point it clicks softly, on that one push rod thats not spurting oil, ,this, indicating the clearance has reached the maximum allowable,
too safely run, and then stop the engine, squirt a bit (maybe 2-3 table spoons)of diesel down on that lifter and let that seep in for an hour then restart the engine and let it run with that lifter softly clicking for at least 15 minutes so it frees up internally.
rockers and rocker nuts and rocker pivot balls should ideally be kept together as individual matched sets , if you don,t have a valve train disassembly tray, tye-wrap the matched parts together
and reassembly with a good coat of moly assembly lube.
have you verified the oil pump pick-up to oil pan floor clearance?
this tends to be reduced when swapping to a high volume oil pump restricting oil flow rates




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By: Jim Hand

Hydraulic Valve Train Adjustments

We often read and hear about "adjusting" rocker arms for more performance. How is it done and what actually is accomplished by adjusting rockers? A quick description of the valve train will help clarify the operation.

The valve train consists of a valve (with springs, retainers, etc.,) a hydraulic lifter, a pushrod, a rocker arm with ball, and a rocker arm stud with nut. The lifter rides on the camshaft and as the cam lobe raises the lifter, the lifter moves the push rod, the push rod moves the rocker arm, and the rocker arm pivots on the stud/ball/nut and pushes the valve open. The hydraulic lifter consists of a main body, an inner body, a small spring, and a check valve. When off the cam lobe, the small inner spring expands the lifter to eliminate all clearances in the valve train, and at the same time, the lifter is refilling with oil via a small orifice in the lifter body from the engine oil feed system. When the lobe starts to raise the lifter, the lifter check valve closes and traps the oil in the lifter. By design, a small amount of oil leaks out during the lift cycle so when the lifter returns to it's rest position, it is slightly shorter than when it started to lift. This prevents the lifter from continuously expanding each lift cycle and holding the valve open when the valve should be closed (minimizing lifter pump-up). When the lifter is back off the lobe, the cycle is repeated. Thus, all valve train noise due to loose valve train components is eliminated during all driving conditions.

All Pontiac engines are produced with non-adjustable valve trains. The rocker arm stud has a shoulder just below the rocker nut threads. The rocker nut has a mating shoulder just below its threads. Normal assembly specifies that the nut be tightened down on the stud to 20 ft. lbs. The mating shoulders of the nut and stud positions the valve train such that the lifter is in the center part of it's travel range and it can eliminate clearances during all normal operation. The 20 # setting is not an adjustment, it simply tightens the nut so it does not come loose.

If valve train noise is noticed, it is usually due to excessive wear in the valve train components. A pressed in stud can move and cause mix-adjustment but it is rare. A stud can be hammered back down by double nutting the threaded end flush with the stud end and smacking it. Excessive noise can sometimes be eliminated by installing a locking type nut and actually adjusting it to a desired position. Do not attempt to change the position of factory type nuts! They will not stay in position unless they are locked down on the shoulder. Small block Chevy rocker arm nuts are lock type and will fit the standard Pontiac 3/8" studs. (If 7/16" studs are used, big block Chevy lock nuts will fit.) Aftermarket nuts containing set screws (called polylocks) work well and can be reused indefinitely. I do not recommend the lock nuts with plastic inserts due to the heat and shock in the valve train. Lifter pump-up, which occurs at relatively high RPM, causes the engine to miss and quit accelerating. Several hundred additional RPM can usually be gained by adjusting the rockers to just eliminate clearance in the valve train and then about 1/4 turn tighter. This assumes the rest of the engine can live at the increased speed, and that increased RPM might help performance. We have found that the larger Pontiac engines generally run quicker when shifted at a relatively low RPM.

The Ram Air IV engine was introduced with 1.65 rocker arms rather than the normal 1.5. If you decide to use the 1.65 arms, you must replace the stock 3/8" rocker studs with 7/16" studs. The stock studs will not allow the rocker arm to be adjusted down to the correct position for normal lifter operation because of the built in shoulder. Standard big block Chevy studs are 7/16" and fit perfectly. Summit Racing has good quality units (Dorman HD.) for about $25. + shipping. I know of no way to use the 1.65 rockers with heads having pressed in studs without excessive machine work. Remember, standard Pontiac rocker arm nuts are not lock type and will not stay in position except on the shoulder of the stud.

Final Adjustment.

The actual adjustments can be made with the engine running or with it shut off (hot or cold). We prefer setting the lifters cold because it is much cleaner and more comfortable.

Adjustment with engine running.

Place newspapers between the heads and the fenders. Cover the fenders. With the engine at normal operating temperature, slow the idle to the slowest speed at which the engine will run. Remove one rocker cover and slowly loosen one adjusting nut until that rocker assembly begins to clatter noticeably louder. Oil may begin to spurt from the rocker arm. Slowly tighten the nut until the noise ceases (which is zero clearance) and then tighten 1/4 to 1/2 turn tighter. Note that when tightening the nut, the lifter has to compensate and it may hold the valve open slightly causing a miss if you adjust too quickly. The lock type nuts should stay at the final setting. If using polylocks, tighten the setscrew firmly. Set the remainder of the rockers in the same way. If several are making excessive noise when starting the adjustments, it may be necessary to temporarily tighten all nuts to eliminate the excess noise while you make final adjustments on each. Reset idle speed.

Adjustment with engine off.

Set the engine to #1 firing position. The timing mark should be on 0 and the distributor rotor should be pointing to #1 cylinder wire. In lieu of removing the distributor cap, remove #1 spark plug and feel for compression in the cylinder as the engine is rotated to the 0 timing mark. Remove the remainder of the plugs for ease in rotating the engine. Remove the rocker covers and adjust the rocker arm locknuts in the following sequence. Thanks to Pete McCarthy for defining this sequence in his book "Pontiac Musclecar Performance, 1955-1979".




#1 firing position, set



Rotate engine 90 degrees CW, set



Rotate engine 90 degrees CW, set



Rotate engine 90 degrees CW, set



Rotate engine 90 degrees CW, set



Rotate engine 90 degrees CW, set



Rotate engine 90 degrees CW, set



Rotate engine 90 degrees CW, set



Note; The 90 degree movement is approximate. The purpose of this positioning is to place the lifter on the side of the cam 180 degrees from the lobe to assure the lifter is on the base circle of the cam.

Each locknut should be loosened during the adjustment until definite looseness (or clearance) can be felt on the pushrod with your fingers. Awhile twisting the pushrod, slowly tighten the locknut. When the first interference is felt, stop. That is the zero position. Make sure you can feel the difference between clearance and zero clearance. Further tightening will compress the lifter, although you may still be able to twist the pushrod. In any case, when you are sure of zero clearance, tighten the locknut ki to 1/4 turn tighter from the zero position and secure the setscrew on the polylocks. Replace the rocker covers and start the engine. It may miss slightly and/or the lifters may rattle until all lifters adjust themselves to the new correct positions.
I just went through changing out all of my valve springs to cure ( I hope) a breakage problem. Grumpy gave me a lot of advice on spring choices, whether he remembers or not :lol:

Anyway, after installation I was able to adjust the valves to where the engine started but it wasn't until I used the valve cover with a window cut in it that I was really able to dial in my lash. Certainly it was my inexperience, but I swear i am learning! Just wanted to say thanks for the help, the info, and this forum!
always glad to help!
tell your buddies about what youve learned as the more info out there in the world the better.
btw tell them about this site also :mrgreen:

If your reading thru this because your installing a new cam, all the info you needs in the links, posted below, ID suggest leaving the car in neutral buring the break-in with the park brake fully on, and having the car parked where you can have a garden hose allowing water to run over the radiator as it drastically improves cooling, then check all your connections, fluid levels and belts and start the engine and set the timing as quickly as you can, keep the engine rpms between about 1700rpm-2600rpm for 30 minutes
read thru the links before starting
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Well for one thing I let my Buddy that spec'd out the parts for my new engine know that the springs initially used were not within margin for 1.6 rockers :twisted:

On the bright side, once I got the new springs in the car really has a lot more power. Still working on the timing since I have high compression heads and run at altitude with 91 octane gas which causes a bit of a ping under load that has been a boooger to address. Which kind of leads me to reading sparkplugs. I have read a lot of the links on plugs and some say the position of the color change on the ground strap is affected by the plug heat, others say it is timing (I think it's timing though). My plugs are almost bone white with color change at the bottom of the strap by the threads. Prior to replacing the springs the ceramic was a light tan to pink color so I am thinking I am getting a higher lift on the valves since I am not coil bound anymore? I know this is off the subject of this thread but it is what it is. As far as timing I have tried to recurve the mechanical and am in at 36* around 2300 rpm... used to be all in at 1100 or so. this is with the heaviest springs I could find (Moroso). I can back off the timing to try to get rid of the ping, but I did this with the original valve spring setup to no avail. Also Lars has mentioned that at altitude it can be better with 38* .. must not be with high compression heads is my guess. Just letting you know where I am at on the car at the moment.. thanks again
"My plugs are almost bone white with color change at the bottom of the strap by the threads."

that plug your describing is a very obvious sign your running too LEAN a fuel/air ratio,and the cylinder temps are running on the hotter than ideal range, or possibly to much ignition advance, you really should address that or you'll eventually be replacing pistons

reading spark plugs is an excellent way to gain info on the combustion chamber conditions and the location of the heat ring on the ground electrode and the color of the plug can tell you a good deal about the combustion chambers temp range.
( verify and change, float levels, fuel pressure,check for vacuum leaks and you'll most likely want too change your jets and power valves, as required)

plugs that look like this are LEAN

plugs should look a bit more like this

even better

reading material










heres some good links on tuning



I,m always rather amazed when I find older guys , that I think should have by now had the time to gain experience or learned how to adjust valves on a car that seem rather clueless about both how to proceed with the process and / or even why valves need to be adjusted.
Ive also found theres at lease 4-5 different ways to go about adjusting valves , and surprisingly most of the processes seem to work reasonably well if you do them correctly.
(obviously you can look back early in this thread for several examples)
and before you even try adjusting valve lash at idle , (while the engines running) you really should consider finding a tall valve cover that fits your cylinder heads and modifying it by cutting out a large section of the top surface as adjusting valves while the engines at idle can get messy


one method Ive used before dozens of time on race engines is what I found to work reasonably well on flat tappet solid lifter combos but be aware its not absolutely precise but it does work and at the race track it saves a good deal of time and Ive yet to see it cause any issues but be warned it takes "EXPERIENCE and a FEEL" for what your doing, it won,t be absolutely precise but it will get you functioning quickly and be very close to the correct lash once you get experience using it..
btw the best deal I found lately on basic hydraulic flat tappet lifters

its based on simple match and being aware of what your doing.
a standard BIG BLOCK ROCKER ARM has studs with a 7/16" stud and 20 threads per inch and 1.7:1 rockers
Rocker Arm Studs
Top Stud Diameter/Thread: 7/16''-20
Bottom Stud Diameter/Thread: 7/16''-14
this means that a full revolution on the stud by the adjustment nut moves the rocker pivot point about .050 up or down the stud, or the tip of the rocker moves about .085, thus a 1/4 turn effectively moves the valve adjustment about .022 which is very close to the .018-.022 that a good many solid lifter flat tappet cams use for the proper lash clearance.
now if your like me and your an old geezer you tend to adjust hydraulic lifters with the engine at idle and you back off the rocker until it clicks, slowly tighten it just to the point the clicking stops and then add 1/4 turn, and lock the rocker nut set screw.





you can adjust solid flat tappet lifters in a vaguely similar way by inserting a proper thickness tappet feeler gauge between the rocker arm tip and valve tip,after loosening the rocker until there's more than enough lash clearance, too allow the tappet feeler gauge to slid in then slowly tighten the rocker nut to just the point where the clicking stops, remove the tappet feeler gauge and lock the nut on the stud at that point, you'll get a smooth rhythmic ticking which is exactly how a properly lashed solid lifter valve train sounds, but the trick hear is this, if you are in a big hurry, you can simply adjust the lifter lash by slowly turning the rocker nut down just to the point the clicking stops then BACKING IT OFF just a bit less than 1/4 turn......think it won,t work? try it and check it with a tappet gauge and you'll be surprised at how consistent the results are if you have the experience to be consistent.
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Intetesting concept of setting Valvelash while the engine is running Grumpy with a Solid Flat Tappet Cam or a Solid Roller Grumpy.
Will give it a try next time.
Always set final valvelash after engine has been running for 20 minutes & engine off.
I can see where your method would save time.

Works Ok with Tight valvelash cams of .014"-.016" ?
87vette81big said:
Intetesting concept of setting Valvelash while the engine is running Grumpy with a Solid Flat Tappet Cam or a Solid Roller Grumpy.
Will give it a try next time.
Always set final valvelash after engine has been running for 20 minutes & engine off.
I can see where your method would save time.

Works Ok with Tight valvelash cams of .014"-.016" ?

that would require a bit more than 1/6th of a turn on a big block 7/16" rocker stud, obviously use of a different rocker ratio or thread pitch would cause a different amount of adjustment but the concept could be used once carefully checked out and you had some practice

if you or anyone else has a
single orphaned, tall cast aluminum BBC valve cover,
or even a tall cast aluminum sbc valve cover,

yes the tall versions tend to work better in this application,

that might care to sell it, reasonably
let me know what you want for it,
Ive owned several,of both versions , but they seem to "get borrowed" and not returned rather regularly

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The Lost Art of Valve Adjustment
By Ray Bohacz from the February 2010 issue of Hemmings Muscle Machines


Nothing is a quicker giveaway of a poorly maintained engine than excessive valvetrain noise. In addition to identifying a poor mechanic, a tap emanating from under the rocker covers can also be responsible for robbing power from any engine. A noisy valvetrain means the valve events are not correct, which will impact the engine’s performance and driveability.

Beyond that, there’s the embarrassment of showing off your car and having it make that noise. Just recently, I ran into someone who had a very nice small-block ’72 Nova that was tapping away as if it were a marching band. When I mentioned the valvetrain noise to the owner, he stated that all GM engines from that era made that sound and that it was normal. When I tried to offer some unsolicited advice, he got nasty and told me I did not know what I was talking about. I left shaking my head in disbelief.

This installment in the Lost Art series will cover how to identify and eliminate valvetrain noise and related performance issues through proper adjustment and service procedures.

Valvetrain Basics
A valve lifter (sometimes referred to as a tappet or cam follower) follows the contour of the camshaft lobe and transfers that motion to open and close the valves. A domestic V-8 engine from the muscle car era will have either solid (mechanical) or hydraulic valve lifters. A solid lifter is a rigid component. In contrast, a hydraulic lifter is designed to accommodate variations in valvetrain clearance in order to automatically maintain zero lash in the valvetrain under all operating conditions. It does this by filling and emptying the lifter with engine oil through a metering orifice and a check valve. When the lifter is filling with oil, it is identified as pumping up; when the oil is exiting the lifter, it is bleeding or leaking down.

The term “lash” is often used when discussing valvetrain adjustment. This describes the amount of clearance between the rocker arm and the valve stem when the lifter is on the base circle of the cam (valve closed). With a solid lifter, there is a predetermined lash or clearance that is checked with a feeler gauge. An engine equipped with a hydraulic cam does not require a feeler gauge. When adjusting the valves on an engine with hydraulic lifters, you are not really setting the lash or clearance–you’re actually setting the preload on the lifter through the pushrod and rocker arm. The traditional adjustment on a hydraulic lifter is zero lash, followed by a predetermined amount of turns on the hold-down nut.

But not all engines with hydraulic lifters have a preload adjustment. If the rocker arm is stud-mounted, such as on a Chevy, then proper procedure involves attaining zero lash plus the specified amount of preload. Some engine designs, such as the Pontiac V-8, use a stud, but are considered nonadjustable in factory form. On these engines, the rocker stud needs to be changed to make the valvetrain adjustable with a hydraulic camshaft. Other designs use a pedestal mount for the rocker and may require shims or an aftermarket rocker arm with an adjustment screw to set the preload. Some engines, including Buick V-6s and V-8s and many Chrysler V-8s, use shaft-mounted rocker arms. With this arrangement, the shaft mounting bolts are torqued to a specification; if the valvetrain is noisy, there is a wear issue or mechanical problem.

A hydraulic valve lifter offers several advantages: no more maintenance valve adjustments, quieter operation due to having no lash, longer valve and cam life due to eliminating the pounding of a solid lifter, smoother engine operation due to precise valve control and automatic compensation for expansion and contraction of the valvetrain parts caused by temperature change.

To understand how the hydraulic lifter is able to accommodate valvetrain slack while maintaining zero lash, we should look at its inner workings. When the valve is closed, the plunger spring in the hydraulic lifter takes up all clearance in the valvetrain. Oil enters the lifter body through feed holes and flows inside to the plunger. The oil continues to flow down through the hole in the bottom of the plunger, around the check valve and through the holes in the check-valve retainer to completely fill the cavity below. As the lifter begins to ride up the cam lobe, the oil below the plunger tries to escape past the check valve. This sudden flow of oil forces the check valve to seat, which seals the hole at the bottom of the plunger. At this time, the full load of the valvetrain is being applied on the lifter, but since a fluid cannot be compressed, the lifter now acts almost as if it were a solid design.

A predetermined and closely held clearance between the lifter’s plunger and its body permits a minute amount of oil to escape from below, moving past the plunger. This movement of the plunger with respect to the lifter body after the check valve is seated is called leakdown or bleed-down; it consists of the oil draining out.

As the lifter returns to the base circle of the camshaft, oil fills the high-pressure cavity and the cycle begins again. When the engine temperature change requires shortening the lifter’s effective length, a hydraulic lifter automatically compensates: the valve spring forces the plunger down. When lengthening the lifter is required, the return spring raises the plunger, causing more oil to flow into the spring cavity.

One of the disadvantages of a hydraulic valve lifter is that it cannot follow as aggressive a cam profile as a mechanical design, thus limiting the engine’s power and operating speed. In addition to the cam profile being milder, a hydraulic valve lifter requires a certain amount of time to respond to changes in the engine; this limits engine power when compared to a mechanical design. Aftermarket performance valve lifters are designed to pump up and bleed down at a different rate than the OE style, but often sacrifice quiet operation and longevity to do so.

Another potential drawback of hydraulic lifters is that at excessively high engine speeds, valvetrain inertia may open the valves further than intended. This results in additional valvetrain clearance. A hydraulic lifter senses this clearance; the plunger begins to lengthen, and may actually extend far enough to prevent the valve from closing. Valve-to-piston collision and a ruined engine can result.

Understanding the Noise
Valvetrain mechanism noise is similar to a clicking sound of a sewing machine. The sound frequency of the valvetrain noise is one-half the crankshaft speed. A clicking lifter is one very common valvetrain noise. If the engine is equipped with solid (mechanical) lifters, fixing this usually requires an adjustment, because the amount of lash or freeplay is excessive.

If the engine has hydraulic valve lifters, however, a number of things could be wrong; further diagnostics are needed.

The problem with diagnosing and correcting valvetrain noise is that there are many components that can cause undesirable sounds. Not every noisy valvetrain is suffering from improper adjustment. For this reason, even after the valves are adjusted properly, the engine may still be noisy. If this is the case, then the problem is not with the lash; instead, a mechanical failure due to wear is probably causing the sound. Though there are many possible causes, the valve lifter is often the source of the noise.

Valvetrain noise can also be caused by sticky valves, weak springs or excessive revving of the engine. In any hydraulic application, another cause of valvetrain noise can be the result of machining of the cylinder head and valve seats, which changes the rocker-arm geometry. Many mechanics think that this is caused by faulty hydraulic lifters; that is incorrect. The lifter is only responding to the conditions and trying to adjust for them. That’s why it is critical to make sure that the valvetrain is the culprit when chasing any excessive noise before it becomes a major issue.

It is important to remember that several different conditions can produce a noise identical to that caused by a failed or failing valve lifter. Some of these are:

If the engine noise is not caused by one of the listed issues and is coming from a hydraulic lifter, you will need to isolate the failed lifter. A simple method is to use a piece of garden hose. Remove the valve covers. With the engine running, place one end of the hose near the spring retainer of each intake and exhaust valve; put the other end of the hose to your ear. It will be very apparent which is the offending valve lifter.

Another way to find a failed valve lifter is with the engine shut off. Push down on each of the rocker arms on the pushrod side. If the rocker arm is free to move or there is a spongy feeling, it is a good indicator that the valve lifter is leaking down too fast or not retaining oil from the engine.

Once you locate the lifter that is causing the noise, you will need to determine the reason for its malfunction. There are four types of noise that can be caused by an inoperative or failing valve lifter:

1) Loud, rapping sound: This can be caused by the plunger being stuck in the body, usually due to excessive varnish between the plunger and body, or by dirt or other foreign materials wedged between the plunger and body. Another cause of a loud rapping sound is an excessively worn base or foot on the lifter itself.

2) Moderate clicking noise: This can be the result of varnish or a worn lifter bottom. The noise level depends on the amount of varnish and the degree of wear. Two other causes of a moderate clicking noise are excessively fast or slow leakdown. Slow leakdown generally will cause the engine to be noisy only when cold and the oil is thick. With fast leakdown, the valvetrain will be noisy when the engine is warm. Fast leakdown will also occur if the ball-check in the lifter fails to seal.

3) Intermittent clicking: This type of noise is hard to locate by its very nature: There will be a few clicks, and then it will be quiet, but the noise will reappear after a short period of time. The usual cause of intermittent clicking is a very minute piece of dirt that holds the ball check off the seat for a few seconds and then passes through. In rare cases, the cause of the sound is a pitted or flat spotted ball-check.

4) General valvetrain noise: When the sound is throughout the entire valvetrain, the cause is usually the weight of the oil or the oil supply itself. Too much oil in the crankcase will cause foaming and aeration. When air gets into the lifters, they will fail to operate properly.

Insufficient oil supply to the lifters can also cause general valvetrain noise. This could be the result of too little oil in the crankcase, an oil pump not operating properly, or clogged main oil gallery lines.

Excessively thick engine oil will cause entire valvetrain noise when cold-starting an engine. The noise will diminish when the oil warms up and starts to flow properly. An engine with thick oil will be more prone to noise in colder weather than during the summer months.

Making it Right
The first step in fixing valvetrain noise and creating the correct valve events is recognizing that valvetrain parts are consumables. All too often, I hear of someone rebuilding an engine but reusing all of the rocker arms, lock nuts, valve springs, pushrods and other components. Even if you’re only trying to quiet the valvetrain, not rebuild your engine, you need to examine every component. You can only properly adjust the valvetrain after removing and closely scrutinizing each of the rocker arms, pushrods and valve stems (the cylinder heads do not need to come off at this point). If the lash on one valve seems excessively loose or tight, that is a red flag that there is something wrong.

A very loose valve may indicate an excessively worn rocker arm, bent pushrod, mushroomed valve stem or the like. In contrast, an excessively tight valve on one cylinder may mean that valve recession is occurring–the valve is starting to pull through the cylinder head. If this is the case, then the cylinder heads need to be removed before the engine drops the valve and puts a piston through the side of the block. More engines are ruined from valvetrain failure than anything else.

The best approach when adjusting the valves on any engine is to remove the valvetrain parts to study them while identifying their location. You want each part going back on where it came from. This is due to wear patterns. If you are replacing the components with new, then it is best to keep the old parts identified so they can be studied for any mechanical problems before the new valvetrain is installed.

My suggestion is that if the engine has been in service for many years, it is best to install new lifters, rocker arms, pushrods and lock nuts. These are inexpensive parts, and you shouldn’t hesitate to replace them. A new lifter can be used with an in-service camshaft, but a new cam always requires fresh tappets. This way, everything is new when you perform the final adjustment and the valvetrain should be nice and quiet, and not pose a threat to the engine.

On engines with rocker-shafts or a bridge between the valves (like on some Oldsmobiles), if the heads or block have been machined, you may be required to install shims to get the preload correct–or you can update to an adjustable system. As always, it is best to familiarize yourself with the proper steps from a factory shop manual before starting the job.

There are many different thoughts on how to position the valves when adjusting an engine with rocker studs, such as a Chevrolet. Some manuals tell you to mark the balancer and then jump around to different cylinders that have the lifter on the base circle of the cam.

Personally, I find that method burdensome. It is often hard to see the balancer on newer engines, I do not like moving all my tools and my fender cover from side to side, and it gives the lifters a chance to bleed down more than I would like. The method that I use is to use a helper or a jumper switch to bump the starter until the cylinder I am working on has both valves closed. Then I am sure the lifters are on the base circle.

Once the lifters are positioned properly, try to twist the rocker arm from side to side to check for play. If all looks good, loosen the lock nut slightly while trying to twist the pushrod between your fingers. When the pushrod starts to turn, stop loosening the nut. Then start tightening the nut while twisting the pushrod between your fingers. When the pushrod will no longer turn, you’ve reached zero lash. Now turn the nut between one-half and one full turn to set the preload. You are now done with that valve. Follow the same procedure on the other valve, and then move on to the rest of the cylinders.

Once all the valves are adjusted properly, you may want to check things out. You can do this in one of two ways: Start the engine with the rocker covers off (be mindful of oil spray), or with the covers just dropped in place with no gaskets or bolts. Listen for any noise and recheck the oil flow to the rocker arms. If all is fine, shut the engine off and button it up. If done properly, the engine should be smooth, quiet and powerful.

The stamped-steel rocker arm that is common with Chevrolet engines uses a center fulcrum to move up and down on the stud. With any engine, the interface between the pushrod and the rocker arm is critical for proper valve adjustment.

A valve stem that is worn like this is the result of a problem elsewhere in the valvetrain. For this reason, the rocker arms should be removed and the components inspected prior to making any adjustments.

The rocker arm needs to be cleaned and examined for a wear pattern. A smooth, shiny area in the middle of the contact pad indicates the proper geometry. If the geometry is wrong, the valve will be riding to one end of the rocker arm.

This is a damaged valve-spring retainer from a failed rocker arm that did not have enough clearance.

An example of a good rocker arm is on the left, while the one on the right has a round area worn by the valve stem. It needs to be replaced.

A worn valve guide will cause the valve and, in turn the rocker arm, to move around, cutting into the rocker stud, as seen here.

This rocker arm suffered from a collision with a broken lash cap. It shattered the lock and dropped a valve into the engine.

This is a Jesel individual shaft-mounted roller rocker arm. The roller tip reduces friction against the valve stem and limits guide wear.

A late-model Chrysler Hemi utilizes shaft-mounted rocker arms with a hydraulic cam. When servicing the valvetrain, you need to examine the shaft for wear.

As shipped from the factory, there is no adjustment to the preload on the lifter with Chrysler shaft rockers. If the dimensions are correct, so is the preload.

When adjusting lifter preload, rotate the pushrod between your fingers.

A mechanical-lifter camshaft has a clearance specification as the adjustment.

The valve lash is correct when the feeler gauge is tight and drags on both sides when being removed.


Pro-Motion Engines LLC
2 Great Meadow Lane, East Hanover, New Jersey 07936
it rarely hurts to watch some guy adjust valves, in a way you may not be familiar with so you can pick up a few tips,
or at least , in the process , you learn and know some way to avoid

I've adjusted lifters(hydraulic and solids with a feeler gauge) at low idle for decades with zero issues, I don't think that posted info added anything other than a different outlook, or opinion, but it was posted to broaden your way of looking at the options.
oil-extreme may have benefits , I doubt it hurts and it probably helps, Visard, states it helps, and he's seen test data, so its almost sure to be beneficial.
I've never seen it mentioned before.