Track73 here’s what you need to know along with pictures.
I used a stock 6X head and a 2.11” x 5.100” valve and the head has a stock valve job.
It has also had the guide cut to accept a positive .530” seal.
The installed height is 1.720”.
With a stock Pontiac retainer there is enough retainer to seal clearance to run .480” lift.
So with a stock retainer you can not run 1.65 rockers.
With a aftermarket comp cams retainer there is a clearance that would allow .580”, so then you can run the 1.65 rockers for a lift of some .515”.
With the 5.100” length valves I would run a Crower 68405 spring.
You will likely have to shim them .030” to end up with about 125 on the seat, but that and the other numbers I posted will swing around if the heads have had a valve job.
You will also need longer push rods to get the geometry right.
Also note that 455s with basically stock 6X heads make more power with 1.65 rockers on the intakes only.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!
1) 1940s 100% silver 4 cup tea server set.
Two dry rotted 14 x 10 Micky Thompson slicks.
1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.
Education is what your left with once you forget things!
Last edited by steve25; 03-27-2024 at 04:25 PM.
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