[HWYSTR455]

Nothing makes a Pontiac different than any other V8 pushrod engine, the same principals apply. If you get different readings from rocker to rocker, than it's an issue with the rockers.

If there's a difference with the distance of the centerline of the rocker stud to the distance to the valve centerline, the issue is with the head. No manufacturer would design a head with different distance. (some exceptions apply, like with porcupine heads, and that's only between intake/exhaust, not from one intake to the next intake for example).

It's like saying distance is different from distributor cap to distributor cap between posts, it's just not so. If it is, it's a problem with the cap.

If you have questions as to how to properly do a half-lift method adjustment, don't take anyone's word from it here, look it up. Compare from example to example, and you will see the common factors.

This isn't that complicated, in the end, the pattern will tell you if it's optimum or not.

And the sweep should be slightly more towards the stud when correct, with the narrowest sweep.

Adding lash adjustment after the initial check in general is a preference, .020 for a HYD or .025 for a solid isn't going to make a big when pushrods are in .050 increments, you go one way or the other, it's not a substantial amount to cause and drastic change. Keep it simple.

If the cam is on the base circle then you count the poly lock turns, if you have the lobe at half lift you need to use a checker spring for either a HYD or solid, and you don't need to count the turns, you just screw the ploy lock down to take all the slack out.

It would be pretty hard to turn the adjusting pushrod to take up the slack if the lobe is at half lift, you would have to compress the spring, and usually adjustable pushrods are flimsy and could deflect from the spring psi.

If you have the lobe at half lift and you add the calculated turns to the poly lock for another half lift value it would simulate being at full lift.

There are literally 100s of youtube vids on the subject, watch a few, it will become obvious how to do it.

Just to throw a twist in though if you want to get anal about it, between the base circle and the lobe starts to actually lift, there is a slight dip where it is less than base circle, but for the most part it's not enough to take into consideration when measuring for rocker geometry. (But it can be a consideration when adjusting lash, which is why EO-IC method is preferred.).

Reference, @8:40 min mark: https://www.youtube.com/watch?v=USBHPOA2akY&t=769s

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[charlie66]

If you're worried about compressing the lifter when checking, I put a small needle nose around the push rod resting on the top of the lifter. It will keep it from compressing.

[charlie66]

If you're worried about compressing the lifter when checking, I put a small vice grip needle nose around the push rod resting on the top of the lifter. It will keep it from compressing.

[steve25]

Here’s a very cool and most accurate way to check and set your VG.

[67Lemons]

Originally Posted by steve25

Here’s a very cool and most accurate way to check and set your VG.

What are we looking at here? The text is mostly covered.

[steve25]

The tool replaces a retainer and the dial gauge sits on the rocker roller.
As you roll the motor / cam thru the full lift range the gauge will move up to the max lift point and then down.

When you have the optimized rod length and or stud height off the head the dial gauge will read the same movement on the opening and closing side of the lobe.

But this can only used with roller tip rockers.

Does not look too hard to fab up if you have thick enough bar stock.

[VCho455]

I had to look deeper into how it worked. Watch the video in the link. It's a pretty interesting way to measure movement across the valve stem.

https://www.wilkesperformance.net/pr...10-degree-lock

[67Lemons]

Originally Posted by VCho455

I had to look deeper into how it worked. Watch the video in the link. It's a pretty interesting way to measure movement across the valve stem.

https://www.wilkesperformance.net/pr...10-degree-lock

That’s actually not a bad price for what you get and if it makes determining the correct pushrod length easy then it might be worth it for the aggravation factor alone.