can I just swap in 1.6:1 ratio rockers?

grumpyvette

Administrator
Staff member
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.

sguide_plate.jpg

pushrodbind.jpg

tippattern.jpg

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

24947101.jpg


STUD-12.jpg

louis2.png

louis1.png




pro-66485_w.jpg


btw place a magnet like this under each pushrod slot to catch the drill chips from iron heads
louist.jpg

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.
RockerGeometry.jpg


clearancefail.jpg


https://www.summitracing.com/parts/pro-66485
louist.jpg

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.
pro-66485_w.jpg


sguide_plate.jpg

pushrodbind.jpg

you need EITHER PUSH ROD GUIDE PLATES

BELOW NOTICE SCREW IN ROCKER STUDS
rockerguide.jpg

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
molypaste.jpg

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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"



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


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
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

stampedcvrockersa.jpg

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


rockeroilfeed.jpg


rockstcl.jpg



check all valve train geometry and clearance on any engine you assemble or modify the valve train on.
bbcvtq5.jpg



bbcrk1.jpg


rockeroilfeed.jpg

longslot.jpg


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
man-42133_w.jpg

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
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

http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/#post-54232
rpo1x.JPG

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

beehivesprcl.jpg

retain6.jpg

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/
pushrodbind.jpg

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.




Go to First Unread



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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