TDCRacing

I need longer pushrods on an engine that I'm building. I'm trying to obtain a measurement to zero lash. Since I am taking a measurement on the valve side with a feeler gauge instead of a PR length checker I would have to divide my measurement by my rocker arm ratio which is 1.7 to get me to my needed measurement of zero lash (or size to increase pr length by)....


Correct?

JPH

iTrader: (2)

I am not sure, I have never done it this way. How short or how much preload do you have NOW with a stock length pushrod?

vettenuts

iTrader: (4)

Yes, if you are using say 0.010" feeler gauge for zero lash, then the difference in motion at the pushrod end is 0.010/1.7 = 0.006" that needs to be added to the final pushrod length to take out the clearance you have established with the feeler gauge.

I like to lift the rocker tip to get zero lash rather than try to rotate the pushrod end. Just gently lift it until the "tick" "tick" just disappears. (If you lift to hard on a dry lifter it will actually depress the plunger in the lifter.) Then you can cross check with the value you get with the feeler gauge.

chrisfrost

iTrader: (8)

These engines are not like small block Chevys that used zero-lash hydraulic lifters ,,,,,,,,,,these have .060-.080" of pre-load so You really need a push rod checker to measure with for what You need ,,,,,,,,,,,

bww3588

iTrader: (49)

Even though the use the exact same lifter....

It is the same, except your setting preload with the length of the pushrod rather than the adjuster nut.

Since the ls has net lash rockers, they are torqued to spec.

chrisfrost

iTrader: (8)

I understand that but the pre-load is how much the piston in the lifter is depressed and unlike small block chevy 1st gen which have zero pre-load, LS based gen 3 / 4 have pre-load

bww3588

iTrader: (49)

I see you've never built a small block Chevy...

chrisfrost

iTrader: (8)

You've got to be kidding Me ,,,,,,right ,,,,,,,,,You're going to let a word interpretation error or a lack of communication sway You're opinion about someone ,,,,,,,,,,Me ? ,,,,,,,Wow ,,,,,,,,,,I really have no reason to explain My credentials so good luck with the language

bww3588

iTrader: (49)

I'm not doubting your credentials, just pointing out that you are in fact...wrong on this.

When you're setting the valves on a small block Chevy, you tighten the rocker nut until you find zero lash. Then go half to 3/4 turn more. That is preload on the lifters.