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Old 01-10-2021, 10:45 AM
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firebirdcrazy1959 firebirdcrazy1959 is offline
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Default 1971 #96 head rebuild ??

So when you have hardened valve seats installed,do they just do the exhaust or both???
I'm going a have my #96 heads done when i get to Cape Coral soon for my 462 that has #62s now..
I am sure the 62's need to have the same done since i did them back in 1995..not many miles since i only drove the car in the summer,

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Old 01-10-2021, 12:44 PM
Mr. G Mr. G is offline
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Always have done just the exhaust valves on the ones I have had done. Never had the machine shop even ask if the intake valves should have hardened seats. I think it is the heat and gasses and lack of lead that come through the exhaust valve that calls for the hardened seats.

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Old 01-10-2021, 01:29 PM
694.1 694.1 is offline
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You should confirm but IIRC, '71 engines had hardened seats.

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Old 01-10-2021, 07:54 PM
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Quote:
Originally Posted by 694.1 View Post
You should confirm but IIRC, '71 engines had hardened seats.
I can’t remember either as I think it was around ‘71 they started. Regardless,the stock 96’s on my ‘71 had many sunk exhaust valves when I tore my engine down. So I had hardened seats put in when I had the heads redone.
On the other hand, I just had the heads redone on my ‘62 Mercury. I opted NOT to go with hardened seats as the car is only driven 500 miles a year. I figured my money could be spent elsewhere being on a tighter budget these days.
I’ve never heard of putting hardened seats on the intake side.

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Last edited by 67drake; 01-10-2021 at 08:00 PM.
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Old 01-10-2021, 08:17 PM
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Later seats went through a hardening process to the cast iron. I've seen rescission in high mileage later heads that were ready for actual hardened seat inserts. Only time we did an intake valve seat is when something went wrong and seat was damaged, and then only on that damaged seat.

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Old 01-11-2021, 02:20 AM
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I have put new seats on the intake side to restore sunken seats on one pair of heads. It was from a piss-poor valve job, not wear. The valves on two cylinders were sunk so bad they were below the roof of the chamber. The others were varying heights and not that great. Normally you only need them on the exhaust side, but if the car doesn't see sustained high RPMs or that many miles, I wouldn't bother if the current seats are in good shape. Just cruising around town and the occasional short trip on the freeway shouldn't wear out your exhaust seats, even with unleaded gas. If you have high 3- to 4- series gearing and drive at higher RPMs a lot then the hardened seats make sense.

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Old 01-11-2021, 06:57 AM
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The Pontiacs usage of a 30 degree Intake seat since day one in 1955 on 99% of the heads wares far less even when the valves and guides are pretty darn loose!

A 30 degree seat clamps to make a seal far more then the wedging action that a 45 degree seat does, especially when a 45 degree set up gets warn and the valve swims around.

This is also the reason a 30 degree seat with a valve like the 2.11" used needs 10 to 12 pounds more seat pressure then a 45 degree seat with the same size valve because a 30 degree seat set up will tend to suffer sealing issues at high rev's more due to valve bounce .

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