1.6 ratio rockers, changing rocker ratios and the effects

[grumpyvette]

One of the most frequent questions I hear, is
" will adding 1.6:1 roller rockers really do much for my engine vs the standard 1.5:1 ratio roller rockers?"
changing just the rocker ratio but sticking to the cheaper stamped ball & socket stock rocker design tends to have a minimal power advantage, the fact that the aftermarket stamped rockers do tend to be a bit more consistent in effective ratio helps but gains of 5-8 hp are common, not the 10-12 hp commonly quoted from what IVE seen on dyno results.
keep in mind the flat side of the rockers axle or trunnion faces up to mate with the adjustment nut, and the rounder side faces the cylinder heads, if you change the rocker ratio the push rod alignment changes and you might need a LUIS TOOL to lengthen the cylinder head clearance slots in the cylinder heads.
be sure to check clearances carefully like coil bind,and push-rod to guide plate alignment and clearances ,verify the rocker slots don,t bind on the rocker studs as this is a common problem with stock stamped style 1.6:1 ratio rocker, verify the push rods don,t bind in the slots in the cylinder head, if they do even for an instant at one point in the rockers arc, they can bind the lifter rotation on the cam lobe and cause the cam to wipe, out the lobe and the lobe & lifter contact area resulting in a quickly failed cam,and/or restrict oil to the rockerss

notice the standard slot length rocker on the left , in the picture above, is self aligning while the rocker on the right would require guide plates for the push rods

some roller rocker too retainer combo clearance issues cause problems easily solved with beehive springs and smaller retainer diameters

for several years even stock BBC engines ,(the markVI and mark V) as opposed to the (mark IV earlier BBC engines)
also don,t use adjustable rocker arms if your running a stock cam and valve train with stock O.E.M. heads you probably can get by without them,
swap to a higher lift cam and a longer duration and aftermarket heads and better valve strings and in my opinion,
you would be very foolish to build and use a performance BBC engine without adjustable push rod guide plates
what you really should do is order these
Dart 27001230-4 - Dart Pushrod Guideplates

viewtopic.php?f=44&t=2839&p=7344&hilit=adjustable+guide#p7344
Proper push rod length is absolutely critical for peak performance—minimizing bent or broken valve stems, guide wear, and energy-wasting valve side-loading friction.
With the lifter located on the round base circle, position the Push Rod length Checker (make sure you have the Checker with the proper diameter hole) over the stud. Ideally the Checker should contact the top of the push rod and the valve tip evenly at the same moment, should the Checker contact the push rod first, measure the gap between the front of the checker and the valve tip, and purchase a shorter push rod of the correct length. Should the Checker contact the valve tip first, measure the gap between the back of the Checker and the top of the push rod, and purchase a longer push rod

http://www.summitracing.com/search/...d-length-checkers?autoview=SKU&ibanner=SREPD5
Proform Pushrod Length Checkers 66789 SBC 3/8" rocker studs

Proform Pushrod Length Checkers 66790 SBC 7/16" rocker studs

Proform Pushrod Length Checkers 66806 BBC 7/16" rocker studs
swapping to 1.6:1 ROLLER ROCKERS from your old standard ball & socket 1.5:1 ratio, stock rockers is usually worth 15-20hp,due too both lower friction losses and a bit more valve lift occasionally youll find the swap to 1.6:1 ratio roller rocker produces a bit more power, the change in lift at the valve with the new higher ratio rocker is a minor factor compared to the reduced friction decent roller rockers provide,along with the lower heat the oil sees from the rocker friction, but together the two factors, higher valve lift and less friction are usually worth the time and effort, swapping from a 1.5:1 to a higher 1.6:1 ration can at times provide little if any benefits but on other combos the results are very noticeable (ON A DYNO)
you also want to remember that you need to carefully check push rod to cylinder head clearances thru the full engine rotation, its fairly common when swapping to the higher ratio to find the push rods rub in the push rod slot in some locations, this can cause wear, noise or lack of oil flow to several rockers, a louis tool can be used to open up the cylinder head rockers push rod slots for proper clearance. (look lower in the thread for more info )especially if your really UNDER CAMED for the application, or find you need extra rocker/push rod clearance

the change in rocker ratio, from 1.5:1 to 1.6:1 would have an effect on valve lift that would look similar to this on a graph

heres a flat tappet solid lifter cam I used to use a great deal in 10.5:1-11.5:1 compression ratio 383-406 sbc race engines, I built, run on race octane gas , changing the rocker ratio from 1.5:1 to 1.6:1 on that cam, boosts the lift from the original .518/.536 too a .552/.571, so you darn sure needed better valve springs and needed to verify clearances

How does an increase in Rocker Arm Ratio improve the engine's performance?
The lobe lift of the cam is increased by the ratio of the rocker arm to produce the final amount of valve lift. A cam with a .320" lobe lift using a 1.50:1 ratio rocker arm will have a .480" valve lift (.320" x 1.50 = .480"). If you install rocker arms with an increased ratio of 1.60:1, with the same cam, the lift would increase to .512" (.320" x 1.60 = .512"). The engine reacts to the movement of the valve. It doesn't know how the increased lift was generated. It responds the same way it would as if a slightly larger lift cam had been installed. In fact, since the speed of the valve is increased with the higher rocker arm ratio, the engine thinks it has also gained 2° to 4° of camshaft duration.

The end result is an easy and quick way to improve the performance of the existing cam without having to install a new one. See the Buyers Guide section for availability of increased ratio rocker arms. Remember, whenever you increase the valve lift, with either a bigger cam or larger rocker arm ratio, you must check for valve spring coil bind and for other mechanical interference. Please review the previous sections concerning these matters.

http://store.summitracing.com/partdetail.asp?part=TFS-30400700&autoview=sku

http://store.summitracing.com/partdetail.asp?part=TFS-30400701&autoview=sku

its very common to find you'll gain a couple horsepower with the addition of a rocker stud girdle employed,
as youll have both more precise valve train control and less deflection, Ive seen guys instantly gain an extra 150 rpm-200 rpm,
before they started feeling valve float or loss of valve train control and its certainly less stress on the cylinder head casting and rocker studs.
the one thing ID suggest is that before you buy any rocker stud girdle you ask questions, many cylinder head designs use non-standard rocker stud spacing.

its not horsepower, its the stress on the valve train, that makes a rocker stud girdle and its increased rigidity useful,

read thru these threads, and links, yeah I know you want to skip over them, but if you do youll skip over a great deal of useful info

viewtopic.php?f=52&t=126

viewtopic.php?f=52&t=198

http://www.superchevy.com/how-to/148-02 ... d-rockers/

http://www.pontiacstreetperformance.com ... rArms.html

http://www.hotrod.com/techarticles/engi ... ock_chevy/

http://www.hotrod.com/how-to/engine/hrd ... m-comparo/

viewtopic.php?f=52&t=10268&p=41624&hilit=ratio+roller+rockers#p41624

viewtopic.php?f=52&t=1719

viewtopic.php?f=52&t=3009

http://www.superchevy.com/how-to/148-02 ... d-rockers/

http://www.wallaceracing.com/rockercalc.php

http://www.popularhotrodding.com/engine ... phr_ratio/

http://wallaceracing.com/rockercalc.php

http://www.dapa.org/jhpages/jhandracing13.htm

http://www.thedirtforum.com/rockercalc.htm

viewtopic.php?f=52&t=196

http://garage.grumpysperformance.com/index.php?threads/rhodes-lifters.1552/#post-6067

http://www.vetteweb.com/tech/vemp_0703_ ... index.html

http://www.vetteweb.com/tech/0204vet_sm ... index.html

http://www.compcams.com/Products/CC-%27 ... %27-0.aspx

http://chevyhighperformance.automotive. ... index.html


Well the answer depend a great deal on exactly which engine your putting them on!
and if youve got the necessary clearances!

If its a fairly mild engine with a mild cam ,and clearances allow, yes there very likely to aid the power curve a bit, you could easily gain 10-12 hp MINIMUM over stock friction BALL style rockers with either ratio ROLLER ROCKER due to the reduced friction alone.
but its not at all unlikely that the additional lift and slight added duration could add 4-5 extra hp in some cases., and since the cost is very similar between ratios for the same application, ITs generally not a bad idea!
now every once in awhile you'll see no gains, but its darn rare to see the larger 1.6:1 ratio cause anything like a loss compared to the 1.5:1 ratio rockers on any combo even close to a stock or slightly modified combo simply because most are flow rate restricted to some degree.

IVE always preferred STEEL roller rockers over ALUMINUM for two reasons
first STEEL has a MUCH GREATER fatigue life under repeat stress than aluminum, and steel generally has far fewer clearance insures with other components, plus some STEEL roller rockers are REBUILD ABLE.
NATURALLY IF YOU DON,T READ THE LINKED INFO YOU'LL MISS A LOT OF GOOD STUFF!

in the picture above, you see self aligning on the left, on the right the common style that needs push-rod guide plates

http://www.vetteweb.com/tech/vemp_0703_ ... index.html

http://www.pontiacstreetperformance.com ... rArms.html

http://store.summitracing.com/partdetail.asp?part=CCA-1302-16&autoview=sku

http://store.summitracing.com/partdetail.asp?part=CRN-11600-1&autoview=sku

in MOST cases you can install 1.6:1 roller rockers with MINOR machine work, (I have seen on rare occasions no machine work necessary)
but in any case its easily done,

the tool comes with instructions

http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRO-66485&N=700+115&autoview=sku

and before a dozen guys start telling you they installed them with zero problems on stock heads, keep in mind most guys don,t take the time to check ALL the clearances thru THE FULL rotation of the rockers arc. and it they don,t break or bind parts ,THEY assume its fine
but the truth is the pushrod should NEVER touch either end of the slot even lightly anywhere in the arc.

more info
http://www.vetteweb.com/tech/0204vet_sm ... index.html


http://www.digitalcorvettes.com/forums/showthread.php?t=82474

http://www.centuryperformance.com/valveadjustment.asp

sure, this type USUALLY fits inside many stock valve covers,naturally youll need the BBC version if its a BBC and the self aligning version on a SBC VORTEC HEAD

http://store.summitracing.com/partdetail.asp?part=CCA-1331-16&autoview=sku

or

http://store.summitracing.com/partdetail.asp?part=CRO-73640-16&autoview=sku

but you might need to get different adjustment nuts as those might be too tall for some valve covers, I know they fit on most corvettes stock covers AFTER use of a DIE GRINDER to remove the DRIP TABS on the inner valve cover surface

READ THRU THIS THREAD AND SUB LINKED INFO ALSO

viewtopic.php?f=52&t=181&p=2342&hilit=guide+plates#p2342

 

[grumpyvette]

Re: 1.6 ratio rockers

If you can,t afford full roller rockers..the aftermarket roller tip rockers are worth the expense simply because they have LONGER slot clearance for the rocker studs and more precise ratios than stock rockers, most are forgings or cast rather than stamped liker stock,and you've stated your stock rockers bind on the studs at near full lift,the roller tips don,t do much, so don,t think that's a big deal.

BUT if I was going to swap rockers, a FULL ROLLER ROCKER DESIGN like I posted is well worth the extra expense as it will free up 7-10 hp MINIMUM due to lower friction alone, remember the vast amount of friction in a rocker is in the rocker fulcrum not the tip. a true roller rocker has roller bearings and an axle so the slot is replaced with a hole for the stud

you'll ALWAYS need to check clearances on any change in the rocker arm or valve train geometry but GENERALLY the rocker slot clearance is much better on the aftermarket roller rockers than on the stock stamped rockers and ID suspect you'll have no problems if the components are properly installed
read this
its not horsepower, its the stress on the valve train, that makes a rocker stud girdle and its increased rigidity useful,
and thats more closely related to average stress levels, RPM and VALVE SPRING LOAD RATES
any time your occasionally exceeding 6000rpm or getting close too 330 lbs of open valve load rate Id strongly suggest screw in rocker studs
any time your intentionally exceeding 6000rpm and exceeding 350 lbs of open valve spring rate a rocker stud girdle might be a good idea.
and if your regularly exceeding 6500rpm and 400 lbs of open valve spring load rate its use is going to become almost mandatory
http://www.summitracing.com/parts/pro-66950

http://www.summitracing.com/parts/sum-141010
self aligning rockers are designed to be used without push rod guide plates they have pronounced ridges to stay centered on the valves, non-self aligned rockers require push rod guide plates
http://www.vetteweb.com/tech/vemp_0703_ ... types.html

LEFT ROCKERS SELF ALIGNING, RIGHT ROCKERS STANDARD STYLE REQUIRES PUSH ROD GUIDE PLATES
NO! you can,t just use either style, guide plates will tend to BIND the push rod with the self aligning style rockers, you can use standard rockers WITH guide plates and SELF ALIGNING rockers WITHOUT guide plates

in this picture the self aligning rocker is the center one with the raise ridges that keep in centered on the valve tip

self aligning stamped rocker

some of the least expensive sbc roller rockers Ive found, now I don,t have any long term experience yet with these but I doubt summit will put their name on TOTAL CRAP, so theres a good chance these will work fairly well

http://www.summitracing.com/parts/SUM-G6936-16/


IVE USED ERSONS EXTREME DUTY ROLLER ROCKERS IN MANY ENGINES OVER MANY YEARS WITH COMPLETE SATISFACTION (notice those are NOT the standard roller rockers they sell)they used to be a slightly different design and usually black in color, but the new version is still a great value

http://www.pbm-erson.com/store.php?catId=481&parent=24

http://www.usaperform.com/extreme-duty- ... p-849.html

 

[grumpyvette]

Re: 1.6 ratio rockers

youve installed 1.6:1 ratio rockers and the pushrods rub...in the guide slots in the cylinder heads,
this is a common problem,easily solved...
YOU NEED A louis tool, YOU WANT ABOUT .060 CLEARANCE, IT MAKES THE JOB EASY
This tool was designed to simplify the modification needed when using 1.6 rocker arms on SB-Chevy heads. It allows you to use a hand drill with a 5/16'' bit to elongate the pushrod slot exactly in line with the existing slot, thus eliminating the need for guide plates.

stock stamped rockers are cheap but the ratio is usually not precise and the slots for the rocker studs can bind at high lift plus they easily restrict 10-15 hp in friction losses.
If your on a tight budget, you also might want to swap out those older stock stamped rocker arms for new stamped steel, ones when you do a compression test, they may be excessively worn and they don,t cost much to replace.
in fact swapping to a set of the stamped 1.6:1 ratio stamped rockers is a cheap, usually have longer clearance slots and grooved rocker balls for better lubrication, and they are usually effective upgrade, if you keep it simple and check clearances carefully you could rather easily gain 10-12 hp from the increased valve lift and usually more consistent ratio, quality control on the parts dimensions.(stock stamped chevy rockers are supposed to be 1.5:1 ratio but they rather frequently actually measure closer to 1.4:1-1.44:1
be sure to liberally coat the ball and rocker with moly lube

before they are installed, as it takes several minutes for the rocker balls to seat and wear in correctly,
https://www.summitracing.com/parts/sum-g6801/overview/make/chevrolet
(BE DAMN SURE you check clearances , especially on the push-rods to cylinder head guide slots)

its rather common to have push rods rub or bind when swapping to the higher ratio 1.6:1 rockers so its mandatory you carefully check EVERY one through its full arc for proper clearance and use a louis tool to extend the push rod guide holes is thats required
this is mostly a matter of carefully checking clearances and verifying valve train
geometry,and use of quality parts rather than selecting the cheapest crap available, in many cases the simple swap of components can be done with few issues ,BUT its rather common for parts too bolt in, but not fit correctly, but LESS-experienced mechanics don,t see the indications of potential trouble,and wonder why parts failed later as a result!
parts that rub or bind and were thought too be correctly functioning only to be found later too be causing rapid wear or even a cam or lifter failure as a result of the parts installer, NOT verifying the correct clearances and geometry, so take your time and read the links and check, never assume a darn thing, fits correctly until you verify the clearances over the full range of movement.

http://garage.grumpysperformance.co...swap-in-1-6-1-ratio-rockers.10671/#post-46039

http://garage.grumpysperformance.co...rocker-ratios-and-the-effects.126/#post-37621

http://garage.grumpysperformance.co...-rocker-ratio-help-your-combo.2632/#post-6790

roller tips are usually more precise ratio rockers but don,t look for any huge reduction in friction

true roller rockers can frequently free up 15-20 hp in reduced friction.


stamped rockers are cheap and dependable but decent roller rockers will frequently allow the engine to run at reduced friction loads, 10-15 hp gains are easily available, and in some cases even more is available especially with higher spring loads or a higher than stock rocker ratio.
http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRO-66485&N=700+115&autoview=sku

viewtopic.php?f=52&t=6641&p=21035#p21035

These Proform push rod slotting tools are designed to elongate the push rod slot in the cylinder head. They will make room for higher ratio rocker arms. Use these tools with a drill and a 5/16 in. drill bit to elongate the push rod slot.

btw place a magnet like this under each push rod slot to catch the drill chips from iron heads

http://www.kjmagnetics.com/proddetail.asp?prod=D82SH&cat=167

many, but not all, aluminum performance cylinder heads already were manufactured with the longer slots, now I generally use ALUMINUM ,BRODIX,TRICKFLOW,AFR, ocasionally DART, heads and I can,t remember a recent set that was needing to be clearanced there. but remember the rockers you sellect, pushrod length, spring height all effect the geometry and the clearances can easily be changed
a rocker stud girdle helps also, as it tends to stabilize the studs flex and minimize the changes in clearances as the springs load/un-load
keep in mind most performance heads your push rod guide plates not the slots in the castings to align the push rods
(BOTH the pushrod guide plates and rocker girdles are usually unique to that particular heads geometry, so make sure what you want fits the application when ordering parts)

http://store.summitracing.com/partdetail.asp?part=TFS-30400700&autoview=sku

http://store.summitracing.com/partdetail.asp?part=TFS-30400701&autoview=sku

cranes gold roller rockers are decent quality rockers for a small or big block chevy,Ive used those, ERSON, CROWER and COMP CAMS ROLLER ROCKERS, many of them come with jam nuts that require a 3/16" allen key
and look a great deal like these posted here below

but these are NOT locking jam nuts designed to work with a rocker stud girdle

http://www.summitracing.com/parts/tfs-3 ... /overview/
BTW.IF YOUR BUILDING A SBC
http://brodix.com/heads-2/small-block-chevrolet-compatible-heads/ik-series
http://www.jegs.com/i/Brodix/158/1021001/10002/-1

brodix ph# 1-479-394-1075 (ALWAYS VERIFY PART NUMBERS SEVERAL,
TIMES FROM AT LEAST TWO SOURCES, BEFORE ORDERING PARTS)
the brodix rock stud girdle is part # BR-6435 and LIST price is about $230 you can get it for less if you shop carefully
BE AWARE that the I.K. 200 heads were shipped with BOTH 3/8" and 7/16" rocker studs ,
and the poly locks for the 7/16" rocker studs ONLY fit that rocker stud girdle
obviously you need to verify what your heads have before you order the matching rocker stud girdle
Verifying your engines clearances, and rocker geometry, and use of A rocker stud girdle and high quality roller rockers go a long way towards maintaining valve train durability

rocker stud girdles require significantly longer shank jam nuts , but you need to mount the rocker stud girdle up out of the way so the upper surface of the rockers can,t touch the lower surface of the stud girdle at full lift
It may surprise many people but even many corvettes came with pressed in rocker studs, the fastest way to visually verify is to look for the hex stud base thats used to screw them in, if theres no hex base chances are excellent that they are press in studs.

typical pressed studs

screw in rocker studs

viewtopic.php?f=44&t=2839&p=7344&hilit=adjustable+guide#p7344

viewtopic.php?f=52&t=126&hilit=louis+rocker

and you may need too use the correct adjustable guide plates when you find the push-rod alignment is in need of minor tweaking to get the clearance and geometry correct

yes you can,use the louis tool with the heads still on the engine, but its highly advisable to remove the intake for easy access and to use a strong vacuum cleaner, magnets and some shop rags in the lifter galley to trap,remove and contain metallic chips the drill thru the louis tool will produce
using a louis tool, this tool is a GUIDE /tool for use with a high quality DRILL,its made of HARDENED STEEL that FORCES the DRILL BIT to drill thru the head to correctly lengthen the push rod slot for increased clearance, they usually come WITH INSTRUCTIONS AND THE NECESSARY DRILL

its rather common to have push rods rub or bind when swapping to the higher ratio 1.6:1 rockers so its mandatory you carefully check EVERY one through its full arc for proper clearance and use a louis tool to extend the push rod guide holes is thats required

 

[grumpyvette]

Re: 1.6 ratio rockers

ok how do i adjust them now?

http://www.thedirtforum.com/chevyvalves.htm

http://www.2quicknovas.com/happyvalves.html



http://www.centuryperformance.com/valveadjustment.asp


http://www.boostandfuel.com/support/setting_valves.htm

http://www.carcraft.com/techarticles/87998/index2.html

http://www.angelfire.com/fl4/pontiacdude428/valveadj.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

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 discribed above

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

HIT A FEW YARD SALES, SWAP MEETS UNTILL YOU FIND A DIRT CHEAP SET OF TALL CAST VALVE COVERS LIKE THESE, the CONDITION THEY ARE IN ,WITHIN REASONABLE LIMITS OF COURSE IS NOT THAT IMPORTANT

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 strenth around the perimiter 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 hydrolic 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 differance 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 recomended 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 useing jam nuts dont forget to lock the allen key

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

or if your really lazy (you can use this method on hydrolic lifters)install the tall cut valve covers and just turn the engine about 20 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) untill it just quits clicking plus 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 hydrolic lifter to add preload,naturally youll need to verify with a feeler gauge.

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

 

[grumpyvette]

Re: 1.6 ratio rockers

Ive tried all the methods listed above.....but I keep coming back the the first method Ive used for 40 years...

I may be old school,but IVE never had a problem adjusting solid lifters,and will continue to do so with this method, 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
eventuality 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 additional 1/4 turn for preload

http://www.cadvision.com/blanchas/54pon ... ppets.html

http://www.pontiacstreetperformance.com ... rArms.html

http://store.summitracing.com/partdetai ... toview=sku

http://www.sjdiscounttools.com/lis68050.html

http://store.summitracing.com/partdetai ... toview=sku

if your offered used roller rockers or go to reuse yours, inspect them carefully, some steel roller rockers are designed to be rebuilt many aluminum roller rocker are basically expendable and designed for use of only a few years then should be replaced as soon as wear becomes obvious much like fan belts or tires are,
carefully inspect the push rod cups for wear,be sure the interior rocker stud hole is the same diam. as your rocker studs, you can,t use 7/16" rockers on 3/8" studs or 3/8" rockers on 7/16" studs the trunnion bearings should rotate smoothly with zero slack and not be noisy, and have a slight resistance not sloppy loose.
the roller tips should rotate smoothly and show no scaring, there should be no galling or burrs or wear indications in the interior rocker stud slot, any snap rings should be tight and they should all be marked with the ratio and have no indication of rust, corrosion or abuse.
there should be 16 rockers that look almost identical

 

[grumpyvette]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

http://www.hotrod.com/techarticles/engi ... chart.html

http://www.hotrod.com/techarticles/engi ... ewall.html
due too the design of most rocker stud girdles and the locking nut designs in many cases your choices will be limited ,
but I prefer to keep the lower rocker girdle surface a minimum of about .060 from any portion of the roller rocker in its arc if I can manage that

SOME ROLLER ROCKERS CAN AND DO BIND ON ROCKER STUDS, or rocker adjustment nuts, youll need to check carefully

some roller rocker too retainer combo clearance issues cause problems easily solved with beehive springs and smaller retainer diameters

the POLY LOCKS that are used with most roller rockers AND ROLLER ROCKER SIZES, (come in a variety of lengths AND DIAMETERS AND THREAD SIZES) so you might find you need tall valve covers to allow clearance BUT in most cases swapping to shorter poly locks reduced that problem from mandating taller valve covers, be aware that the outside diameter of the locks is a darn important factor in allowing the rocker to reach full potential lift!
it should be obvious that youll need to carefully check clearances over the full rotation and lift in several areas if you chance valve train components and retainer to rocker and internal rocker clearance slot to poly lock are two of many potential places the valve train may bind if theres not the correct clearance

you may find this informative

 

[87vette81big]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

http://www.hotrod.com/techarticles/engine/hrdp_1305_rocker_arm_comparo/rocker_arm_product_chart.html

you may find this informative

The Crower Enduro 17-4 ph Stainless Steel Rocker Arms are the highest rated in Open spring pressure capabilty @ 1200lbs.
The same rocker arm has been around since 1968.

Any thoughts on Crower's Roller tip needle bearing option Grumpy?
Worth the extra $ ?
Found Crower Stainless Enduro rockers to be the best.
Only better is shaft rockers.
Would purchase Crower stainless shaft rockers if building all out race engine & budget allowed.

 

[grumpyvette]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

Crower stainless rockers have been rated about in the top 10% for decades, Ive rarely used them only due to cost issues , I would use them much more if I had the cash,as they are a quality part. Ive used the ERSON premium aluminum rockers and the comp cams STAINLESS steel rockers on most engines and as of yet not had any issues.
but theres little question that the crower rockers are a component well worth using if the budget allows

 

[87vette81big]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

Yes the price of Hard engine parts have gone up tremendous Grumpy.

When we were circle dirt track racing only Crower stainless Enduro Rockers & Comp Cams Stainless held up long term.
Ran 1/2 set of Crower 1.6 & CC Stainless.
Scorpian Rockers my driver told me were the best ever made lasted 5 laps 1/4 mile @ 7500Rpms. 6.86 Rearr diff gear used. Low. & High 4th Saginaw 4-speed withvReverse.
STAINLESS ROCKERS USED & NO ISSUES FOR 2 YEARS RACING FULL BORE.

Crower Stainless Enduro 1.65:1 Rockers on my 1970 T/A.

 

[grumpyvette]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

heres a bit of info I found posted elseware

"Rocker Breakage!
– What Typically Causes It – Too Much Spring Pressure, Bad Geometry, Wild Camshafts?

Factory rocker arms were designed to run a long time in the atmosphere of a stock engine. Subjecting them to increased spring pressures or aggressive cam profiles can be a disaster. Trunion bearings, axles, nose wheels, and pushrod cups can fail at any given time. Quality aftermarket roller rockers are designed with high performance hazards figured into the equation to help prevent these failures.
Aftermarket roller rockers can be, manufactured from a variety of materials. Before choosing a particular rocker package, one should have a complete understanding of the duty requirements of the rocker arms. The lower cost, lighter duty kits were designed to replace stock or milder cam and spring combinations. They are often manufactured from low cost, cast aluminum. They will not stand up to the rigors of stiff valve springs or extreme camshaft ramp speeds. The higher end kits which are made from high quality billet aluminum like 2025 t6 for instance, can withstand incredibly aggressive cam profiles and very high spring pressures. This particular alloy actually becomes stronger as the temperature rises. Steel is often used in the most expensive rocker arm kits, but it too can be subject to failure. When a steel rocker arm breaks, it is usually in the area of the trunions or trunion bearings. An oil pan full of needle bearings is a bad thing. While aluminum is not as strong as steel, it has some flexibility which allows the rocker body to take much of the punishment rather than the trunion.
Extreme camshaft ramp speeds cause the lifter to have difficulty maintaining contact with the camshaft lobe.
This condition is often referred to as "valve float". Aggressive or poor cam lobe designs or opening ramps with high acceleration rates can literally hammer the rocker arms and other parts of the valvetrain. To help control this condition, engine builders usually move up to stiffer valve springs. While this tends to solve the immediate problem, other issues generally appear. Exceeding the manufacturer’s recommend / allowable spring pressure is a sure way to kill the rocker arms. When in doubt, step up to the next level rocker arm. Doing the job twice is always painful. Determining which rocker to use for your particular application is the responsibility of the engine builder.
High pressure valve springs cause sever loads on the pushrods. These loads imparted into the pushrod cause it to bend and then return to a straight configuration. This unloads a sharp energy pulse to the rocker arm, which transfers it into the valve/valve spring assembly. Continued abuse can cause the rocker arm to fail. A better choice would be to utilize lighter valves, lifters, retainers, lighter / stiffer pushrods and moderately stronger springs.
Improper rocker arm geometry can place the rocker in disadvantageous positions which cause severe loading to the rocker. Too much of this, and the rocker arm can fail.
Insufficient clearances can subject the rocker arm to contact with other immovable objects. Coil bind, piston to valve clearance, retainer to seal clearance, etc. can force sever loads on the rocker arms that are not part of manufacturing concepts. The result, of course, is rocker failure.
One final cause of rocker demise is poor engine oiling. This can occur for a variety of reasons. Often overlooked areas that can cause serious oil pressure loss are the cam bearings and the main bearings. Improper / loose specs here allow a great deal of oil to escape and never reach the upper end and rockers. Poor oiling starves the trunion bearings, axles and nose wheels. Add aggressive cam profiles and high spring pressures to the equation and rocker arm failure is imminent. "

 

[87vette81big]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

The latest article posted by You Grumpy is a shining example of magazine & newbie racer forum hype can be a fatal valvetrain mistake.
Destroy a race engine in a few seconds.
Experience you have Grumpy is priceless.

Valvetrain float with todays radical ramp speed cams not hard to do by accident.
Weakest link will fail 1st.

 

[grumpyvette]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

http://www.summitracing.com/parts/crn-11759-16

cranes gold roller rockers are decent quality rockers for a small or big block chevy,Ive used those, ERSON, CROWER and COMP CAMS ROLLER ROCKERS, many of them come with jam nuts that require a 3/16" allen key

and look a great deal like these posted here below

but these are NOT locking jam nuts designed to work with a rocker stud girdle

http://www.summitracing.com/parts/tfs-3 ... /overview/

BE aware you need to verify rocker adjustment lock nut to rocker slot clearance and yes it varies even with the same manufacturers different rocker designs

thanks for posting that rather interesting oil deflector video, I'm sure it will be a factor in more than a few of those sets of valve covers being sold, simply because of the obvious advantage they provide in adjusting the valves at idle without hacving to deal with 90% of the potential mess that would ocur with standard valve covers.
those valve covers and the simply oil deflector that can easily be fabricated make even the open top valve adjustment valve cover modification that several of my friends have look like a great deal of extra work being done for no real reason.
damn I wish they made similar valve cobers for the BIG BLOCK CHEVY

http://garage.grumpysperformance.com/index.php?threads/adjusting-valves.196/
READ LINK
viewtopic.php?f=52&t=4564&p=12170#p12170

http://www.competitionproducts.com/Joma ... o/JOM1114/

rocker stud girdles require significantly longer shank jam nuts , but you need to mount the rocker stud girdle up out of the way so the upper surface of the rockers can,t touch the lower surface of the stud girdle at full lift
notice the recessed hex on the rocker stud lock nut used with the girdle, cranes roller rockers require a adjustment nut with a .600 diameter , to keep the rocker with its slightly larger slut from deflecting to the side, as the body of the jam nut helps stabilize the rocker , and the nuts are made with matched thread pitch and a stud girdle with the correct stud spacing.
stud girdles significantly strengthen the rocker studs because all 8 studs on a cylinder head resist movement of each individual stud as its subjected to stress as the cam lobe compresses the valve spring and the stud tries to deflect, not just a single stud.... shop carefully and ask lots of questions and its usually a good idea to buy matching components from a single manufacturer if possible for all the valve train components as it tends to avoid mis-matched parts causing clearance or geometry issues.

 

[grumpyvette]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

just a bit of info, I was recently made a gift of a set of crane 1.6:1 self aligning roller rockers.... off an LT1 corvette engine when one of my friends had his LT1 engine basically self destruct at the local drag strip .
http://www.summitracing.com/parts/crn-1 ... lications/
notice these are the self aligning type

http://www.summitracing.com/parts/crn-1 ... lications/
In, exchange for some advice and, time, effort and help removing a damaged engine, as hes planing on going with a LS series engine swap upgrade and let me have the trashed LT1 without even opening it up to see what was salvageable, once he saw a large hole in the engines oil pan.
he only wanted help removing the damaged engine in return.
once I got the engine back to the shop I found the rockers and the throttle body and water pump, were about the only salvageable components.
I cleaned and carefully inspected the roller rockers then installed those on my 1996 corvette,(price was right! :mrgreen: ) the result was that to my surprise I didn, need to extend the push rod guide slots and they fit with zero issues under the stock rocker covers,
and while I have not dyno tested the result, its obviously a slightly noticeable increase in low rpm responsiveness that I think makes a worth while improvement (especially at my cost---a couple hours of work on a friends car plus 45 minutes on my corvette to do the rocker up-grade swap.)

 

[Indycars]

Re: 1.6 ratio rockers, changing rocker ratios and the effect


Did you have any concerns about the valve springs?

 

[grumpyvette]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

Did you have any concerns about the valve springs?

good question I had my doubts, but I did check, and didn,t just blindly assume I could swap rockers, and I should have pointed that out, I got out a few checking tools and a louis tool in case it was required,and while it might seem complicated the whole checking process took less than 20-30 minutes, in fact that was the vast majority of the time it took because O used an air ratchet to remove the old rockers and had the engine up and operational very quickly after I checked clearances , and adjusting the rockers was childs play

REMEMBER TO CAREFULLY CHECK THE PUSH ROD TOO CYLINDER HEAD GUIDE SLOT AND CYLINDER HEAD CASTING CLEARANCES,IF THE PUSH ROD BINDS IT MAY CAUSE A LOSS OF OIL FLOW THROUGH THE PUSH ROD, FROM LIFTER TOO ROCKER OR THE LIFTER TO WEAR RAPIDLY
checking all valve train clearance issues in mandatory
its rather common to have push rods rub or bind when swapping to the higher ratio 1.6:1 rockers so its mandatory you carefully check EVERY one through its full arc for proper clearance and use a louis tool to extend the push rod guide holes is thats required
STOCK SPECS
Camshaft Specs (12551705): 205/207 duration @ 50*, .447/.459″ lift, 117 Lobe Separation Angle
LIFT WITH NEW ROCKERS ONLY
.490 which is well under the .540 I saw on the valve with the least clearance
..540-.460=.080 clearance , swapping rockers increased lift to .490 still leaving .050 which while not ideal is safe, as that was the least measured most had a few thousands more, and if I need more I have both better aftermarket valve springs and .050 off set keepers

Proform Parts 66830 - Proform Cam Checking Fixture Kits

http://www.summitracing.com/parts/pow-p ... /overview/

I slowly hand turned the engine and found, before I started out that even at full valve lift with the old rockers ,I still had well over .090 to spring bind and a bit less to the retainer to valve seal clearance

http://www.harborfreight.com/multiposit ... -5645.html

http://www.harborfreight.com/1-inch-tra ... r-623.html

http://www.harborfreight.com/32-piece-s ... 32214.html

just be sure you have the correct clearances,rocker geometry

viewtopic.php?f=52&t=181

viewtopic.php?f=52&t=399

viewtopic.php?f=52&t=1376

http://garage.grumpysperformance.com/index.php?threads/upgrade-choices.11416/#post-52422

http://www.summitracing.com/parts/sum-906784/overview/

 

[87vette81big]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

Nothing wrong with Free Hotrod parts gifts Grumpy.
:mrgreen:

 

[Indycars]

Re: 1.6 ratio rockers, changing rocker ratios and the effect


I was really thinking about the spring in the context of the lifter lofting off the top of the cam lobe or the valve bouncing on seat. I wonder just how much the move from 1.5 to 1.6 would change the acceleration of the valve train.

Is it a simple math problem of 1.6-1.5/1.5 = 6.6% increase in acceleration?

 

[grumpyvette]

Re: 1.6 ratio rockers, changing rocker ratios and the effect
http://garage.grumpysperformance.co...s-on-valve-spring-pressures.10268/#post-43515

lets do a bit of math
just a bit of info on intake gaskets sizes to match port cross sectional areas

Calculating the valve curtain area
The following equation mathematically defines the available flow area for any given valve diameter and lift value:
Area = valve diameter x 0.98 x 3.14 x valve lift
Where 3.14 = pi (π)
For a typical 2.02-inch intake valve at .500-inch lift, it calculates as follows:
Area = 2.02 x 0.98 x 3.14 x 0.500 = 3.107 square inches
SO lets do a bit of math
a cylinder head with a 2.02' intake valve and a cam with a .450 lift at the valve with a 1.5:1 rocker will in theory produce a valve curtain area of 2.79 sq inches, swapping to a 1.6:1 ratio increases the lift to .480 lift 2.98 sq inches, increasing the available port flow potential at least in theory by about 6%, but keep in mind the port can only flow at full valve lift for the limited time the valve remains at full lift and if the narrowest section of the port cross sectional areas less that the valve curtain area that not the valve restricts flow
THUS the most you can reasonably expect is a 6% flow increase , from the rocker ratio upgrade but reality and the fact that the valve is opening and closing perhaps 57 times a second at peak rpms, and the port may be more restrictive that the valve curtain area, on many small block combos suggests the results will be lower

RELATED INFO
viewtopic.php?f=52&t=148&p=34936&hilit=calculate+port+stall#p34936

viewtopic.php?f=52&t=5537&p=16750#p16750


USE THE CALCULATORS
http://www.rbracing-rsr.com/runnertorquecalc.html
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php

COMMON SBC INTAKE PORTS
felpro # 1204=Port Size: 1.23" x 1.99"=2.448 sq inches

felpro # 1205=Port Size: 1.28" x 2.09"=2.67 sq inches

felpro # 1206=Port Size: 1.34" x 2.21"=2.96 sq inches

felpro # 1207=Port Size: 1.38" x 2.28"=3.146 sq inches

felpro # 1209=Port Size: 1.38" x 2.38"=3.28 sq inches

felpro # 1255 VORTEC=Port Size: 1.08" x 2.16"-2.33 sq inches

felpro # 1263=Port Size: 1.31" x 2.02"=2.65 sq inches

felpro # 1266=Port Size: 1.34" x 2.21"=2.96 sq inches

felpro # 1284 LT1=Port Size: 1.25 x 2.04''=2.55 sq inches

felpro # 1289 FASTBURN=Port Size: 1.30" x 2.31" 3.00 sq inches


the valve curtain area, cam duration and lift controlling that curtain area,or port cross sectional area will pose a restriction to air flow at some point,in the engines rpm band, but you can extend the effective air flow duration and efficiency with carefully timed exhaust scavenging, that helps draw in the intake runner inertia load of air/fuel,charge much more effectively if the peak negative pressure wave is correctly timed

 

[Indycars]

Re: 1.6 ratio rockers, changing rocker ratios and the effect


Area = valve diameter x 0.98 x 3.14 x valve lift
Where 3.14 = pi (π)
For a typical 2.02-inch intake valve at .500-inch lift, it calculates as follows:
Area = 2.02 x 0.98 x 3.14 x 0.500 = 3.107 square inches

The 0.98 factor used in the formula above must be for approximating the actual VALVE SEAT DIAMETER.

2.02 x 0.98 = 1.98 inches.

If you know the actual valve seat diameter, then you could use that in the calculation. With so many other factor affecting the results, it's all just an approximation at best.

Does that sound right or might you have more comments Grumpy ???

 

[grumpyvette]

Re: 1.6 ratio rockers, changing rocker ratios and the effect

your obviously correct that exact measurements would be preferable here , but I know from experience not one guy in a hundred will take the effort to actually measure so I figured I,d try to keep the idea, I was posting about, rather easy to grasp, keep the math minimal ,and hope the point gets thru.
I can,t begin to tell you the number of times Ive grabbed snap gauges and a dial caliper and got questioned about what I was measuring when checking port throat restrictions or runner cross sections.
and in case some guys still don,t grasp it the point is that your dealing with a rather complex system with several potential restrictions and simply throwing a good flowing intake on an engine or increasing the rocker ratio may or may not provide an increase in flow potential, the result depends on how the rest of the components flow and react to the component being changed or the mods you've done, there's always several components that act like weak links in the chain, so locating those and improving those gets the best results, but of course once they are radically improved other components can become the new weak link or restriction.
changing the rocker ratio increases valve lift enough in most cases to make a measurable difference in port flow and on most engines its worth a few extra horse power, but thats not always the case because its easily possible that on something like a TPI corvette with a decent set of heads and an aftermarket cam, that the increased potential flow is already restricted by the intake, in cases like that the higher rocker ratio typically helps low and mid rpm torque but the peak power shows little or no increase due to the intake reaching port stall well before the heads flow potentials fully reached.
so your trying to maintain a balance that potentially allows you to reach and exceed the power goals while hopefully not going bankrupt

here,s a chart FROM THE BOOK,HOW TO BUILD BIG-INCH CHEVY SMALL BLOCKS with some common cross sectional port sizes
(measured at the smallest part of the ports)
...........................sq inches........port cc
edelbrock performer rpm ....1.43.............170
vortec......................1.66.............170
tfs195......................1.93.............195
afr 180.....................1.93.............180
afr 195.....................1.98.............195
afr 210.....................2.05.............210
dart pro 200................2.06.............200
dart pro 215................2.14.............215
brodix track 1 .............2.30.............221
dart pro 1 230..............2.40.............230
edelbrock 23 high port .....2.53.............238
edelbrock 18 deg............2.71.............266
tfs 18 deg..................2.80.............250

Potential HP based on Airflow (Hot Rod, Jun '99, p74):
Airflow at 28" of water x 0.257 x number of cylinders = potential HP
or required airflow based on HP:
HP / 0.257 / cylinders = required airflow

related info

viewtopic.php?f=55&t=1509&p=3459&hilit=fast+porting+intake+runner#p3459

viewtopic.php?f=52&t=333

viewtopic.php?f=52&t=8460

viewtopic.php?f=52&t=462