Checking Valve Lift

[Dean Feiock]

Using my 305 as an example, I have seen valve lift checked several ways. Assuming you have the correct lifter with the correct pushrod cup height, which way is the correct way or should I say NHRA approved way to set .000" lash?

1)Rocker adjusting nut turned hand tight?

2)Rocker adjusting nut turned down untill .001" retainer movement is established?

In my case, with 200+ LB's of seat pressure, the difference between the two methods could be more than a half turn on the adjusting nut. One half turn on a 7/16-20 stud would be .025".

As I said, I have seen tech check it both ways. Can Travis answer this or should I send a note to Tech?

[ss3011]

The times I had to bring my Pontiac stocker through a teardown, I brought my own 2 lifters, that I had welded the cup to lifter body. Once the Tech guy accepted them I, installed them in the block with the same pushrods I was running, reinstalled the rockers and poly locks. With the lifters on the base circle of the cam, the Tech guy set the poly lock setting by hand by rotating the pushrod, while he hand tightened the poly lock, Basically he tightened the poly lock until the push rod just wouldn't turn. He always asked me if I thought it was too tight, and allowed me to feel the load on the push rod. If I thought it was too tight he would redo it. I have never had a problem with that technique, and it always checked a little under spec. Best thing to do at home is to run all the different set up procedures, so you know what the effect is. Too tight is not so good as I remember.

[Alan Roehrich]

You really want to get anything like that in writing. You also need to know that NHRA uses their own lifter if they're checking a participant's lift. It may or may not be the same height as the one you have.

I'm not sure Travis can post on this, since if he posted on an official question, it may be construed as an official answer.

[Dean Feiock]

Originally Posted by Alan Roehrich

You really want to get anything like that in writing. You also need to know that NHRA uses their own lifter if they're checking a participant's lift. It may or may not be the same height as the one you have.

I'm not sure Travis can post on this, since if he posted on an official question, it may be construed as an official answer.

Alan, I'm well aware of the checking lifter. I have been checked before. My question is in regards to the preload.

I have been checked both ways, with finger pressure preload and dial indicator preload. I guess just like the cylinder head runners, it's up to tech discretion.

[Rory McNeil]

Originally Posted by Alan Roehrich

You really want to get anything like that in writing. You also need to know that NHRA uses their own lifter if they're checking a participant's lift. It may or may not be the same height as the one you have.

I'm not sure Travis can post on this, since if he posted on an official question, it may be construed as an official answer.

Not always, in 2004, when I had to tear down my 85 Mustangs 302, our Div.6 Tech team did not have a SB Ford hyd. roller lifter in their kit. I had to dissasemble one of my lifters, and plug it so they could check the cam. (Later I made up my own checking lifter.) As for lash/preload, since they check with a solid lifter, I would imagine that any drag on the pushrod while turning it would indicate "zero lash".