reasonably safe valve train clearance for new 383 sbc cam instal

Grumpy

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
how much lift can one safly in a 383 with speed pro flat top with 2 valve relief pistons with a quench of .038 before you have to really worry about PVC. i know you should really check any time you change to a bigger cam my buddy has a vega with a 383 in it and its a pain to get engine out. its easier to pull grill and radiator out. also clearance on rods to cam. thanks

ok just got engine specs from my buddy he bought car already built. so these could or could not be accurate this is what seller gave him in description. 383 with speed pro flat top pistons setting .010 in the hole. .028 compressed head gasket which gives it a .038 quench.scat crank scat pro stock 5.7 rods clearanced for stroker afr 195cc eliminator street heads 75cc combustion chambers 2.05 intake valve 1.6 exhaust valves comp cams 212 intake 218 exhaust duration @ .050 112 lsa .488intake lift .495 exhaust lift.performer rpm intake.
he was thinking about installing a howards cam with 227 intake duration 233 exhaust duration @ .050 .560 intake lift .560 exhaust lift 112 lsa. unless anybody has better ideas thanks he is not looking for max lift just feels the cam in engine is just to small. thanks
Click to expand...
yes you need to as stated, many times on this and other websites, check all your valve train clearances carefully, but in this case theres almost certainly no cause to be concerned here as the minor difference in spring load rates and installed heights is probably well within the intended valve train and cams design limitations, keep in mind the max cam lift is .520
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those heads (keep in mind that price is for a single (1) cylinder head)
https://www.summitracing.com/parts/tfs-30410001/overview/

OBVIOUSLY YOULL WANT THE CORRECT VALVE SPRINGS

http://www.competitionproducts.com/1500-1585-OD-Valve-Springs/products/2631/1/0

https://www.summitracing.com/search/part-type/valve-springs

https://www.iskycams.com/cart/valve-springs-c-99.html

http://www.cranecams.com/userfiles/file/334-343.pdf

https://www.racingsprings.com/Valve-Spring/Store/13

http://www.lunatipower.com/Category.aspx?id=23

http://www.pspring.com/products/engine-valve-springs/

http://www.competitionproducts.com/Valve-Springs/departments/49/

http://psisprings.com/products/

http://www.compcams.com/Products/CC-'Valve Springs By Usage'-0.aspx

http://www.racingsprings.com/Beehive-Valve-Springs

https://www.supertechperformance.com/valve-springs-p109

http://www.cvproducts.com/index.php/psi-springs/

you might also want to keep in mind theres a great deal more to setting up a valve train than slapping some springs and retainers and keepers on the valves.
read thru the links and sub links as theres a great deal of useful info, that youll want to know.
btw just a bit more info, there are valve spring retainers, valve spring seats, shims, valve retainer keepers etc. that can be used that have different sizes or depths that allow you to change the installed height, or relation of the spring to the valve stem , it compressed height, or the valve springs location in relationship to the stems locking groove
keep in mind shims under the valve springs can be used to raise the spring or shorten the valves installed height, valve locks and retainers can be purchased with non-O.E.M dimensions to adjust the valves installed height or spring load rates
you use either or both depending on the application
a .050 PLUS valve lock moves the retainer .050 higher on the valve stem with no other changes, a plus .050 retainer would move the retainer .050 higher with stock valve locks or an additional .050 if matched to .050 plus locks
if you used a plus .o50 retainer with a set of minus .o50 valve locks the retainer would remain at the stock height on the valve stem

http://www.jegs.com/p/Crane/746983/10002/-1

http://www.jegs.com/p/Moroso/764349/10002/-1

http://www.jegs.com/p/Manley/940089/10002/-1

http://www.jegs.com/p/Comp+Cams/757964/10002/-1
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re-read these threads,
linked here and obviously youll need to verify all the valve train clearances and valve spring load rates,
if the valve train geometry check tool and the narrow sweep marks indicating wear on the valve tip indicates the geometry is correct,
your good to go on push rod length

http://garage.grumpysperformance.co...rect-custom-length-pushrods.14241/#post-72366

http://garage.grumpysperformance.co...sh-rod-length-checker-tools.13735/#post-70650

http://garage.grumpysperformance.co...-rockers-and-the-pushrods-rub.198/#post-46839


GrumpyThe Grumpy Grease MonkeyStaff Member

https://www.crower.com/clearance.html?cat=1541

you might want to buy a few of these
while they are on sale at a reduced price

heres a bit of useful related push rod length info (POSTED HERE) youll want to select the correct set or SETS for your shop

Big Block Chevy, Standard Length Big Block Intake 3/8" / .080" 8.275"
295-7941-8 Big Block Chevy, Standard Length Big Block Exhaust 3/8" / .080" 9.250"
295-7969-8 Big Block Chevy, Standard Big Block +.100" Long Intake 3/8" / .080" 8.375"
295-7979-8 Big Block Chevy, Standard Big Block +.100" Long Exhaust 3/8" / .080" 9.350"
295-7951-8 Big Block Chevy, Standard Length Big Block Tall Deck Intake 3/8" / .080" 8.675"
295-7961-8 Big Block Chevy, Standard Length Big Block Tall Deck Exhaust 3/8" / .080" 9.650"
295-7800 V8 396-454 Retro Fit Pushrod Set, Intake & Exhaust, 1965-Present
3/8" / .080"
3/8" / .080" 7.725 Int.
8.675 Exh
295-7913-16 Small Block Chevy, Standard Length Small Block Chevy 3/8" / .080" 7.800"
295-7984-16 Small Block Chevy, +.100" Long 3/8" / .080" 7.900"
295-7934-16 Big Block Ford, Standard Length Ford `72-'78 429-460 3/8" / .080" 8.550"
295-7951-16 Big Block Ford, Standard Length Ford `69-'71 429-460 3/8" / .080" 8.675"
295-7582-16 Oldsmobile, Std Length 455 5/16" 9.550"



prctool.png


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
youll have to correctly measure the clearance on your heads with the valve springs and cam specs you selected too use to know if you have the correct valve spring installed height and clearances, failure to accurately check frequently results in very expensive repairs and to what new guys frequently blame on the cam when it was a installers ignorance that was the true cause.

https://www.summitracing.com/parts/pro-66902/overview/

https://www.summitracing.com/parts/sum-900032/overview/

https://www.summitracing.com/parts/rsc-pac-t902/overview/

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valve springs must be installed at a specific semi compressed and listed installed height,
to provide the listed load rates and clearances,
example

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the cam you select will generally come with a suggested listed valve spring load rate and installed height,
(NOTICE THE SUGGESTED INSTALLED HEIGHT WITH THIS CAM IS 1.800"
and the loads are listed)
you must maintain minimum coil bind and retainer to valve seal clearance and proper push-rod and rocker geometry
the distance between the lower edge of the valve spring retainer and the cylinder head is adjustable to achieve the desired valve spring height through the use of valve spring seat cups and shims placed under the valve spring which can be purchased to lock into a stock height, or plus or minus about .050, and valve locks that cam move the retainer (stock or aftermarket) an additional .050 either tighter or longer allowing the valve spring to expand taller, shims can be placed under the valve seat hardened cups that are almost always mandatory on aluminum head but may be optional on iron heads,(O.E.M. cast iron and lower valve spring load rates)

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max lift is installed height minus .060 minus coil bind
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related info you really need to read
http://garage.grumpysperformance.co...ring-installation-questions.12833/#post-66460

http://garage.grumpysperformance.co...-loads-and-installed-height.10709/#post-46658

http://garage.grumpysperformance.co...ve-spring-iinstalled-height.12791/#post-66038

http://garage.grumpysperformance.co...train-clearances-and-problems.528/#post-57678

http://garage.grumpysperformance.com/index.php?threads/valve-springs.9613/#post-50556
http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/

push rod to short
WIDE SWEEP ON VALVE TIP FROM ROCKER ADDS ADDITIONAL,
SIDE LOAD WEAR
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push rod to long
correct.jpg


push rod length correct
AS CLOSE TO CENTER AS POSIABLE BUT BEING CENTERED IS LESS IMPORTANT THAN MINIMAL SWEEP ON THE VALVE TIP< INDICATING MINIMAL SIDE LOADING
http://garage.grumpysperformance.co...-pushrods-and-check-info-you-might-need.5931/
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
a few simple tools will tell you if clearances are ok
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READ THESE LINKS CAREFULLY

http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/

http://garage.grumpysperformance.com/index.php?threads/checking-piston-to-valve-clearances.399/

http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/
If your ordering any cam, be very sure you explain what year block and what cylinder heads will be used as there are differences in the cams. between early and later SBC, block s and the cams they require,and on big blocks theres similar issues, a mark VI cam is different from a MARK IV cam
its generally a very good idea to keep all the cam, lifter,valve train and cylinder head components in matched sets, keep components in labeled matched sets, if you intend to reuse used parts in a rebuild. as each wears in, or laps in to its matched components a bit differently thus random assembly increases the chances of future parts
failures
btw, if the parts will be sitting on a shelf in the work shop while you wait, a good soak with wd 40, and wrapping a few criss crossed layers of saran wrap plastic over the loose parts is a good idea as it prevents moisture damage and tends to keep the parts in the correct location slots, and if your working on more than one engine type out some detailed info as to the build ID and place it under the saran wrap.
you need EITHER PUSH ROD GUIDE PLATES
BELOW NOTICE SCREW IN ROCKER STUDS
rockerguide.jpg


OR SELF ALIGNING ROCKERS (BELOW)
USED WITH PRESS IN ROCKER STUDS
rockersGP002.jpg


used with press in rocker studs
pressedstud.jpg

rockersGP009.jpg

yes they DO MAKE ROLLER ROCKERS IN BOTH STANDARD AND SELF ALIGNING VERSIONS
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check all valve train geometry and clearance on any engine you assemble or modify the valve train on.
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if your heads have push rod guide plates you are not supposed to use self aligning rockers as yes they will frequently bind the push rods up and keep them from spinning, if you have guide plates you want the NON-self aligning rockers
as I've pointed out dozens of times a day spent reading links will save you a week of work and a wheelbarrow full of wasted cash.
Id also use 1.6:1 roller rockers on a mild 383 SBC build in most cases
http://www.pbm-erson.com/Catalog/Erson/Camshafts/Retro_Fit Hydraulic Roller_E/ERSE119815
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https://www.ebay.com/itm/Erson-Cams-803-16-SB-Chevy-Extreme-Duty-1-6-Aluminum-Roller-Rockers-7-16-Stud/173036288915?_trkparms=aid=222007&algo=SIM.MBE&ao=1&asc=20160908110712&meid=dd2ef46908f84d1994db01594e3da770&pid=100677&rk=4&rkt=8&sd=173036285468&_trksid=p2385738.c100677.m4598

http://garage.grumpysperformance.co...s-in-vs-threaded-rocker-studs.2746/#post-7475

http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/

http://garage.grumpysperformance.co...-in-vs-threaded-rocker-studs.2746/#post-43539

http://garage.grumpysperformance.com/index.php?threads/push-rods-rub.13031/#post-67779

http://garage.grumpysperformance.co...-rockers-and-the-pushrods-rub.198/#post-56571

http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

http://garage.grumpysperformance.co...-pushrods-and-check-info-you-might-need.5931/

http://garage.grumpysperformance.com/index.php?threads/stock-gm-push-rod-length.3844/

http://garage.grumpysperformance.co...ve-spring-iinstalled-height.12790/#post-66037

http://garage.grumpysperformance.com/index.php?threads/more-bent-push-rods.12401/#post-61890

http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/#post-54088

https://www.summitracing.com/search?SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=POW735002

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when your checking, a valve train, and spring clearances, your far better off too deal in proven facts, and verified measurements,
guessing will only get very expensive when you find out your wrong!
yeah I know we all have buddys that say they installed a similar cam and had zero issues
the truth is that many guys who say things like that, won,t tell you about the bent valves, broken push rods, broken rocker studs ETC. that they had only a few weeks later....
yes it takes a bit of effort do check and the links should help, but trust me its far faster and less expensive to do things carefully checking clearances the first time, than to wonder how your going to afford to replace p[arts in a few weeks time!
(and in some cases have zero idea what caused parts to fail when the valve train binds)
http://garage.grumpysperformance.com/index.php?threads/checking-piston-to-valve-clearances.399/

http://garage.grumpysperformance.com/index.php?threads/limited-oil-choices-for-cam-break-in.13602/

http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/

http://garage.grumpysperformance.co...-pushrods-and-check-info-you-might-need.5931/

http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/
while that sounds like the newer cam will add a noticeable power increase,
you will DEFINITELY NEED to verify clearances on piston to valve and valve train,
components as that increase in lift and duration has a good chance,
of potential clearance issues
and before someone suggests it, installing the cam and rotating the engine to see if it binds is an absurdly easy way to find out you bent or broke components, just because you can,t feel it bind does not indicate proper clearances

http://garage.grumpysperformance.co...-loads-and-installed-height.10709/#post-46662

http://garage.grumpysperformance.co...u-buy-bare-or-assembled-heads.534/#post-41292

http://garage.grumpysperformance.com/index.php?threads/busted-valve-spring.7716/#post-38047

http://garage.grumpysperformance.co...pring-cooling-via-engine-oil.6491/#post-20681

http://garage.grumpysperformance.com/index.php?threads/vortec-spring-upgrade.6175/#post-19304

http://garage.grumpysperformance.co...per-valve-spring-seats-shims.1005/#post-15534


http://www.competitionproducts.com/1500-1585-OD-Valve-Springs/products/2631/1/0

https://www.summitracing.com/search/part-type/valve-springs

https://www.iskycams.com/cart/valve-springs-c-99.html

http://www.cranecams.com/userfiles/file/334-343.pdf

https://www.racingsprings.com/Valve-Spring/Store/13

http://www.lunatipower.com/Category.aspx?id=23

http://www.pspring.com/products/engine-valve-springs/

http://www.competitionproducts.com/Valve-Springs/departments/49/

http://psisprings.com/products/

http://www.compcams.com/Products/CC-'Valve Springs By Usage'-0.aspx

http://www.racingsprings.com/Beehive-Valve-Springs

https://www.supertechperformance.com/valve-springs-p109

http://www.cvproducts.com/index.php/psi-springs/
 
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Things expand when they heat up so what might spin free might get real expensive after an engine warms up. I know allot of thought is going into my valve train. That bump stick can make or literally break that engine. I feel allot of people don't understand how much having a properly matched and clearance valve train has on an engine. But then again allot do not see how important matching components properly and adding the correct modifications is to design and create a race engine.
 

louis tool/swapping to 1.6:1 ratio rockers

Grumpy? can i install a set of roller rockers,1.6 ratio in my l79 engine with having my pushrod holes elongated to accept the 1.6 ratio? https://www.youtube.com/watch?v=dFe7kSSeNiw https://www.hotrod.com/articles/roller-rocker-ratio-test/...
garage.grumpysperformance.com

checking piston to valve clearances

this is an old post I got asked to repost, naturally the first step is to install and correctly degree in your cam, http://garage.grumpysperformance.com/index.php?threads/measuring-piston-dome-volume.17255/...
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Does Different Pushrod Length Change Valve To Piston Clearance

Guys, I went from an incorrect length (8.950) to a correct length (9.034) pushrod. Does that change valve to piston clearance? I compensated for the shorter pushrods with the lash adjuster screw. In fact I "compensated right out of oil circulation" with T&D Rockers. Now that I have the correct...
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Retainer to seal measurement. SBC

Rebuilt my 350 sbc and used summit racing part # 152123 iron heads. The head said it takes up to a .520 lift. I installed a Melling 22135 cam and all the matching parts springs, retainers and keepers except for the Howard retro roller lifters. I'm also using 1.5 roller tip rockers. Did all my...
garage.grumpysperformance.com

Retainer to seal measurement. SBC

Rebuilt my 350 sbc and used summit racing part # 152123 iron heads. The head said it takes up to a .520 lift. I installed a Melling 22135 cam and all the matching parts springs, retainers and keepers except for the Howard retro roller lifters. I'm also using 1.5 roller tip rockers. Did all my...
garage.grumpysperformance.com

valve train clearances and problems

you might want to read thru these links and sub links it will help you avoid costly mistakes http://www.summitracing.com/parts/pro-66830/overview/ https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html...
garage.grumpysperformance.com

sellecting valve springs, and setting up the valve train

How do you determine the spring pressure needed to keep the valves under control for a given lift, duration, and max rpm. It might take you several hours to read thru all the links and sub links but its time very well spent as it could save your engine from destruction and save you thousands of...
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rocker/push rod wear issues

Put vortec heads on my L98 and ordered 1417 1.52 Roller Rockers and 7808 Pushrods from CompCams. Installed screw in rocker studs with guide tool before assembly of the engine. Checked valve geometry and the roller left a mark right on the center of the valve like its supposed to. Oil pressure...
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How Does Rocker Ratio Affect Lca?

How does Rocker Raito affect LCA? To narrow it down we have a 30 over 327 461X heads with the 1.94 valve & flat top piston w/ two valve depressions. The cam has a 112 LCA - Maybe a little wide...
garage.grumpysperformance.com
 
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Isky claims that the Comp XE cams violate the 47.5% rule. The 47.5% rule applies to flat tappet cams for SBCs with 1.5 rockers but the concept is still the same for other configurations where the designs are "on the edge" or "over the edge" for lobe intensity. For 1.5 ratio SBCs, the duration at .50 must exceed 47.5% of the total valve lift or your asking valve train problems. For example, take a Comp Cams Magnum 280H, with 230 duration and, 480 lift...230/.480 = 47.9% which exceeds 47.5% therefore would not pose a threat to components. We do not regularly hear about the older, safer HE and Magnum designs rounding off lobes anywhere near as often as the XE cam designs. Unfortunately, some of the Comp Cams XE dual pattern lobes break this 47.5% rule on the intake side so they are likely to be problematic. The design has "steeper" ramps that are too quick for durability and reliability according to other cam manufacturers. They will wipe lobes in a heart beat especially if you have not followed the proper break-in procedure. Other designs are more forgiving during break-in and less likely to fail.
ones got 215 duration with .450 lift,215/450=.47.7%
the others got 215 duration with 510 lift/215/500=43%
 
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