2butterbeans said:I have a 350 with a small cam and I want to change the rocker arms from the stock 1.5 to a roller tip 1.6. Can I do this without any trouble ? Thank you
If your thinking you can swap to the 1.6:1 rockers without checking clearances carefully, ...probably not, your certainly going to need to check and verify clearances , and yeah, youll find a dozen guys that say they did it with zero problems......many could also tell you that in a few months they experienced a cam lobe /lifter or rocker failure as the push rod binding in even only part of the rockers arc, tends to cause excessive wear on the valve train, it might take some time but it will result in component failure over time if parts can,t move freely as designed.
youll want too use a .060 clearance too the push rod to cylinder head slot clearance CHECKED CAREFULLY OVER THE FULL ARC OF THE ROCKER TRAVEL FOR A FULL TWO ENGINE ROTATIONS
if you need a LOUIS TOOL to lengthen the slots in the cylinder head I generally lay a section of plastic wrap in the lifter gallery and be sure to place two magnets on the blocks lifter gallery wall, to hold the thin plastic wrap in place firmly, below the cylinder head while drilling to catch the metalic debris the drill will generally produce, between the plastic sheat and the magnets youll generally catch 100% of the trash the drill generates
btw place a magnet like this under each pushrod slot to catch the drill chips from iron heads
These Proform pushrod slotting tools are designed to elongate the pushrod 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 pushrod slot.
https://www.summitracing.com/parts/pro-66485
These Proform pushrod slotting tools are designed to elongate the pushrod 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 pushrod slot.
you need EITHER PUSH ROD GUIDE PLATES
BELOW NOTICE SCREW IN ROCKER STUDS
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)
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"
Reduced
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push rod too short
WIDE SWEEP ON VALVE TIP FROM ROCKER ADDS ADDITIONAL,
SIDE LOAD WEAR
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
be aware that you need to measure BOTH the intake and exhaust push rod length as they can be different and ON the older BBC are designed to be totally different length, theres also 3/8" and 7/16" diameter BBC push rods and STANDARD AND TALL DECK SETS, and it should be obvious that the guide plates need to match the push rod diameter, being used, in each application as well as the correct length selected.
wall thicknesses vary from about .060 up through about .140 on most designs materials vary also, and larger diameters tend to be significantly more rigid resisting deflection under higher spring load rates, and inertial loads due to more radical roller cam lobe designs and higher rpms.
http://www.cpgnation.com/forum/threads/ ... etry.4346/
http://www.cpgnation.com/forum/threads/ ... tech.2408/
http://www.hotrod.com/how-to/engine/hrd ... vesprings/
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
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
OR SELF ALIGNING ROCKERS (BELOW)
USED WITH PRESS IN ROCKER STUDS
used with press in rocker studs
yes they DO MAKE ROLLER ROCKERS IN BOTH STANDARD AND SELF ALIGNING VERSIONS
the grooved rocker pivot ball design was an effort by G.M. engineering to economically solve the issue of marginal oil flow causing rocker ball galling, and resulting noisy, or broken valve trains
check all valve train geometry and clearance on any engine you assemble or modify the valve train on.
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.
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
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
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
http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/#post-54232
some roller rocker too retainer combo clearance issues cause problems easily solved with beehive springs and smaller retainer diameters
look through this thread
http://garage.grumpysperformance.com/index.php?threads/two-loose-valve-locks.9687/#post-47884
http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/
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.
related info, reading the linked info will help avoid problem
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/
http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/
http://garage.grumpysperformance.co...swap-in-1-6-1-ratio-rockers.10671/#post-46039
http://garage.grumpysperformance.co...to-fit-roller-rockers-and-stud-girdles.12208/
http://garage.grumpysperformance.co...rocker-ratios-and-the-effects.126/#post-37621
http://garage.grumpysperformance.co...o-rockers-and-the-pushrods-rub.198/#post-3033
http://garage.grumpysperformance.co...-rocker-ratios-and-the-effects.126/#post-1193
http://garage.grumpysperformance.co...rdering-correct-custom-length-pushrods.14241/
Last edited: A moment ago
Grumpy, 15 minutes agoEditHistoryDeleteIPReport
#2+ QuoteReply
read thru the links and sub links they may open your eyes
viewtopic.php?f=52&t=126&hilit=louis+tool
http://garage.grumpysperformance.com/index.php?threads/upgrade-choices.11416/#post-52423
viewtopic.php?f=52&t=528&p=45493&hilit=+long+slot#p45493
http://www.popularhotrodding.com/engine ... phr_ratio/
viewtopic.php?f=52&t=181
viewtopic.php?f=52&t=1376
viewtopic.php?f=52&t=2746&p=43539&hilit=busted+rocker+stud#p43539
viewtopic.php?f=52&t=7716&p=29797&hilit=broken+spring#p29797
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