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Old 01-19-2020, 12:05 PM
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Default 1971 #96 heads info

Hi: Just looking for confirmation on info of #96 factory heads.

What size screw in rocker stud?
Factory CC size?
Going on a 455, so CR?
Factory valve sizes?

Thanks for any help
Charles

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Old 01-19-2020, 12:16 PM
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Chuck
I had a set on a 455 years ago:
7/16" studs
96cc's
About 9:1 CR
2.11/1.77
Jeff

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Old 01-19-2020, 12:27 PM
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Thank you Jeff..

Charles

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Old 01-19-2020, 02:32 PM
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Well, listed as 96cc's but the four virgin pair I have come across were right at 101cc's. They were still a little over 96 after a mild cleanup cut.

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Old 01-19-2020, 06:08 PM
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Originally Posted by lust4speed View Post
Well, listed as 96cc's but the four virgin pair I have come across were right at 101cc's. They were still a little over 96 after a mild cleanup cut.
Yup. My 96’s cc’ed around the 100-102 range. I had a few sunk valves too

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Old 01-20-2020, 07:33 AM
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As posted in 4 and 5 you had better CC them, as they are never as low as 96 CCs in chamber volume , and one you get that number if your then getting a valve job done on them then that will add another 1.5 to 2 CCs to the chamber volume .

if you use new valves you might only add 1 CC to the chamber volume if it does not take much meat off to get the seats in fresh shape again.

Most of these heads that I have had on my flow bench produce Intake flow numbers of 200 cfm@.500" @ 28" and out the Exh side 165 cfm@.600" @28".

With a 80% Exh to Intake ratio if you run a single pattern Cam of .525" to .550" lift and have a 9 to1 comp ratio you will have 390 hp in control of your gas peddle !

Another thing to know about all Pontiac iron head is that the factory sets up the Intake valve seat OD some .050" to .070" smaller then the OD of the valve used.

This means that a valve job done with the right angles to bring the OD of the Intake seat out to within .010" of the valve OD with pick up a nice chunk of air flow up to .300" lift.

Keep this in mind!

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Last edited by steve25; 01-20-2020 at 07:41 AM.
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Old 01-20-2020, 11:45 PM
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Quote:
Originally Posted by 67drake View Post
Yup. My 96’s cc’ed around the 100-102 range. I had a few sunk valves too
Yeah, I had a set of 96's years ago on a 455. Engine ran great until a lifter bottomed out. One of the exhaust valves had sunk about .150 and several others were over .100 deep. This was after about 50k miles.

GM claimed that all '71 and up heads had hardened exhaust seats. Obviously my heads did not come that way.

So, if you intend to do any serious amount of street miles, hardened exhaust seats would be a good idea.

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Old 01-21-2020, 12:49 AM
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I got down to 12.07 with unported 96s on my 455. I thought the hardened seat heads were the X heads with Olds looking exhaust. ?
My brother is sitting on a complete std bore 71 GTO engine someone gave him when they put a Chevy in the car. Thanks !

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Old 01-21-2020, 07:23 AM
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I don't man!

I ran 96s on my street Blower motor for 15 years and some 25k miles with the spring pressure needed for a solid roller and never had a Exh valve ression with .070" wide Exh seats and factory RA4 valves, not even stainless steel!

To this day I don't like the finish a cutter leaves for a seat when compared to a fine cut stone with a tight set up!

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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!
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Old 01-21-2020, 09:00 AM
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Quote:
Originally Posted by hgerhardt View Post
Yeah, I had a set of 96's years ago on a 455. Engine ran great until a lifter bottomed out. One of the exhaust valves had sunk about .150 and several others were over .100 deep. This was after about 50k miles.

.
Do you recall which cam you used and if you were using a fast bleed down lifter?

Headers or exhaust manifolds?

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Old 01-21-2020, 01:08 PM
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I ran these heads with the dreaded xe284. Engine dyno 450h/ 532 t. Dipped into the 11's once, 11.98 @ 3700lbs. Ran 12 oh's all day long.

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Old 01-21-2020, 01:16 PM
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450 flywheel hp should take a 3700 lb car to under 11.50 times if it's all getting hooked up.

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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!
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Old 01-21-2020, 01:27 PM
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I ran these heads with the dreaded xe284. Engine dyno 450h/ 532 t. Dipped into the 11's once, 11.98 @ 3700lbs. Ran 12 oh's all day long.
Were your heads ported?

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Old 01-21-2020, 06:55 PM
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We've had to go with hardened seats with some 96's and also 6X heads. Couldn't tell you whether some weren't originally hardened properly or maybe other abuse over the years prompted seat erosion? Last set of 6X's did have some water damage and it seemed to attack the exhaust seat area more than other parts of the chamber.

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Old 01-21-2020, 07:10 PM
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450 flywheel hp should take a 3700 lb car to under 11.50 times if it's all getting hooked up.

Originally had 4.10 gear and 13% slippage. It's tongue was hanging out at the stripe. I believe it had an 80 in with the Jim Hand Converter. Never went to the track with that.

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Old 01-21-2020, 07:15 PM
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Quote:
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Were your heads ported?

They were cleaned up maybe 10-15 cfm. At lift they were 213 - ish.
Yanoski went through them.

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Old 01-22-2020, 01:21 AM
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Do you recall which cam you used and if you were using a fast bleed down lifter?

Headers or exhaust manifolds?
This was in the late 80's with a hyd flat tappet with standard lifters. Cam was approx same duration as a RA IV with .460-ish lift but no clue now who made it. Mostly highway miles, but the engine always ran fairly warm, first in a '66 GTO with a then-original radiator and later in a '68 Bird.

The GTO had cheap headers and the Firebird had its stock log-style manifolds.

The GTO had 3.08 gears with T-400 and the bird had 2.56's with a T-400.

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