zzcamaro00

ok, im trying to measure push rod length with the comp cams 7702 push rod length checker.

now im using the method that i read here in my how to rebuild gm ls series engines(which is my bible lol)

basically it says to adjust the checker length short enough to where it doesnt contact the seat in the rocker but to make sure its seated in the lifter cup then mount the rocker and bolt it down, with other rockers installed to keep the rocker stand from shifting while measuring push rod length. (measuring from the base circle of the cam)

then it says to turn the checker to where it is completely seated in the seat of the rocker and the lifter being careful not to cause any lifter preload, this measurement being 0 lash, no up and down movement of the rocker and pushrod.

then remove the rocker and remove the length checker and to count the turns back to the base checker length which is 6.8

now every complete turn of the checker is .050 thousandths of an inch

so for example lets say i had 9 turns of the length checker

which equals out 9 turns X .05(the length of every complete turn)+6.8 (the base length of the checker)

9x.05+6.8=7.25

then at this point we would add the manufactures specification for preload then we would have the correct length pushrod....correct?

above numbers are an example, as to where i dont make it to complicated

now the particular lifter im running is the lunati 72332 link bar lifter, which the lifter plunger does take some pressure to depress, but when it is depressed by hand it does return to the very top of the snap ring holding it in, so it would be rather difficult to depress the lifter by turning the push rod length checker.

zzcamaro00

any takers?

Ryan@BallisticSpeedParts

iTrader: (3)

Yes, all of your steps in the measurement process are correct.

We run about .030" preload on LS7 style lifters. I'm pretty sure the Lunati's will want around .030"-.050", but I would just give them a quick phone call to verify their recommended preload.

Then add the preload # to your zero lash pushrod measurement to get your final pushrod length.

zzcamaro00

alright, i did call lunati twice first guy said .020-.030...which made me really scratch my head...cause i havent seen that little preload for these particular lifters...the second guy said .030-.040...but ive also read where "they" recommend .030-.050.

so im right on the money then

Thank you for finally replying!!

Ryan@BallisticSpeedParts

iTrader: (3)

No problem, glad you got it worked out.

Burken01

iTrader: (88)

@ryan

I'm running .030 preload on my ls7 lifters as well...

Why did you choose that much preload vs the normal .050-.080?

I'm trying to gather some ideas and take it all in

JakeFusion

iTrader: (7)

That is the correct method. Also correct on using another rocker to hold down the rocker pedestals from shifting around on you.

.050" preload would be ideal for those lifters.