jig for elongating pushrod holes
 

Anyone have the jig for performing this step they would be willing to rent?

There is no jig. Plus they really should not need elongated if you use 5/16 push rods. The only reason they are elongated on Ram Air IV is because RA IV have 11/32 push rods.

There are drill jigs made to do this on some engines. I think it's called a louis tool? It's relatively inexpensive. I have one here somewhere for SBC heads. Unfortunately as far as I know you Pontiac guys don't get one. At least not that I've seen anyway.

There is / was one for Pontiac produced by Paul Spotts, two versions soft and hardened
I bought the soft one and it didnt last long because of side loading of the cutter

If i was to buy another one i would work the slot by other means and use his tool as a go no go guage so you know when your done and dont get any surprizes after the head is already on

Spot Eye by Paul is a fixture that does the oval. I used a grinder and rattail file

Yea on the 400 in the 81 TA I THOUGHT I had ground enough! Had already torques heads down. Had to stay with 1.5s. I used Spotts tool on another set of heads-not used yet and it takes a lotmore in the middle-where my grind job failed. A drill press and some angled shims can get it done , a Bridgeport would be easy to get the angle right.

Spotts has the tool.

If you not porting the heads / opening up the push rod pinch then just run a 1/2” drill bit down thru the 4 push rod holes in each head that are the tallest.

In 10 minutes your done!

Rattail file works great for the final bit of clearance.

This is great to know Steve. I did a little port work, but it was almost exclusively in the bowl area., and widening of the port floor.

You can still widen the pinch like.035" and run down a1/2" bit without going thru the casting.

You will however need a strong drill.

A 3/8" chuck model and one of those 1/2" bits that neck down to 3/8" will not get it done unles you use intermediate size bit before the 1/2".

If you still want more clearance at the top and have a chamfer bit or a unibit then use that some at the very top of the hole.