Problem is exhaust pushrod tips are flattened and worn, intakes are fine. Thought polylocks were coming loose so I tightened a couple of times before spying the pushrods.

Non-roller cam, hyd. lifters, OEM pushrods, tbi swirl heads, OEM valve parts except for springs- don't know anything about them.

Comp cam XE249H .444 lift with 1.5 exhaust and .463 lift with 1.6 intake. Proform roller split set. I am sure the 1.6s were on the intakes.

No other signs of damage like debris next springs.

So, the intakes with the higher lift are fine while the lower lift exhausts are all damaged.

The only thing I know is the exhaust retainer is thicker, does that leave less spring travel? Could the springs bind at less than .444 lift?

Remember, before blaming the Proforms, the intakes are fine.

It takes several hundreds of miles before the rockers start ticking and performance diminishes.

Would there be too much cylinder pressure on the exhaust valve when it starts to open? Never heard of that myself.

 

Not to sound stupid, but you can check to see if the exhaust springs are binding yourself.

Rotate the crank until the exhaust valve is all the way open (or damn close) and slide a .020-.030" feeler gauge in between the coils while it's going through max lift.

Keep the feeler gauge moving (sliding back and forth) and if it stops moving you have trouble.

The other thing would be the retainer hitting the valve seal or valve guide, but you can check that to. You'll have to remove the spring and measure the lift range to see though.

 

check geometry check the springs like was said above are you mixing locating methods?

 

Think this did it?

The one on the left is the 1.5 on the exhaust with the lifter up. It is hitting the slot in the head. The middle is the 1.6 swapped in. The right is an OEM swapped in.

Two things could be the cause. Roller cam heads relocate the slots for the shorter pushrod/longer lifter and the proform design does not work with longer pushrods of flat lifters. Or, proform rockers do this on all GM heads with pushrod slots.

I never heard of the later nor have I ever known the slots in the heads to be relocated.

 

are your rockers SA or non-SA? what are you heads set up for SA or non?

 

ol' fashion non-SA. The reason for the contact is, as I believe, the Proform design is a touch too long compared to OEM rocker as seen in the photo.

I am just wondering if this indexing would cause the pushrod tip to flatten or do I need to keep checking other posibilities? What does indexing usually do as far as damage goes?