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Old 07-30-2020, 10:27 AM
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Default #96 head ?

Do 1971 #96 heads have hardened exhaust valve seats? Going to have a valve job done and going with new valve guides and the guy said new exhaust seats also if they don't have already..
Using new valves and springs.

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Old 07-30-2020, 10:42 AM
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the exhaust seats do not have the high level of induction hardening that later 4X-5C-6X heads do, thats from long time national Pontiac engine builder (45 years exp). Have a heavily worked pair of 7K3's, even though will be mixing some leaded race fuel in the tank, had hardened exhaust seats installed.

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Old 07-30-2020, 10:42 AM
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General rule...All 71s in the industry got hardened seats.
(read it on the Interweb!)

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Old 07-30-2020, 12:09 PM
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I do my own valve jobs and I have run a casting number 96 with roller type solid lifter spring pressure needed to get a motor to 6500 rpm cleanly on unleaded fuel for 20K miles without issue .

I made my 30 degree Intake valve seat .065" wide and my Exh seat .080" wide so if your machinist can provide you with those numbers and you use stainless steel valves you will be fine and not need hardened seats installed on the Exh side.

Make sure he does not apply a 3 angle valve job to the Intake , all you need is the stock 30 degree seat and .150" tall 60 degree bottom cut.

On the Exh side to get that .080" wide 45 degree seat you will only beable to get a slight 60 bottom cut in there, and that's fine!

Also have him apply a 30 degree back cut on your Exh valves to give you a remaining .080" wide seat on the valve.

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Old 07-30-2020, 12:22 PM
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Ran a pair of 1971 #66 455 heads and after 30k miles the exhaust seats had recessed 1/8” or more on most of the chambers. 068 cam, Edelbrock 5857 springs and stamped steel RAIV 1.65 rockers.

I would advise getting hardened seat inserts installed.

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Old 07-30-2020, 12:32 PM
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B man, please answer all of these questions in detail because they all add up to having good seat life or not.

And how wide where your valve seats on both the head and on the valves if they where used valves?

Where they factory valves or stainless steel?

How was your tune, on the lean side?

What was your valve guide clearance?

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Old 07-30-2020, 01:43 PM
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1971 #96 heads will not have induction hardened exhaust valve seats.

GM had the induction hardening process in place across the board by the 1973 model year, not 1971.

There were some 1972 heads that got hardened seats but as a general rule most will not have them........Cliff

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Old 07-30-2020, 01:52 PM
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Funny how people advocate the use of regular seats with unleaded gas

As soon as lead dissapeared from gasoline auto manufacturers hardened the exhaust seats

They must of ran some tests and figured out there wasn't a problem with new valves new valve guides with correct carburetor calibrations reflecting a new production engine and decided to waste money on a useless feature anyway

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Old 07-30-2020, 05:20 PM
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according to Rocky's latest book, the hardened seats on OEM Pontiac cylinder heads was first done for the 1972 model year.

Even if no one else chimed in I would have said "no" to hardened seats for 1971 #96 heads.

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Old 07-30-2020, 05:37 PM
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The 72 7F6 heads I had redone for a recent 455HO build didn't have hardened seats in them. They do now

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Old 07-30-2020, 06:54 PM
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The #66 heads I had were acquired from a friend. I took them apart to install screw-in studs then reassembled them after cleaning. They weren’t perfect and they weren’t completely worn out. Wasn’t running lean.

I think it’s wise to install hardened exhaust seats in any head you’re rebuilding no matter what year the head was manufactured, others may think differently.

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Old 07-30-2020, 08:18 PM
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As a data point was there any 1.77 exhaust valve heads with hardened seats ?

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Old 07-30-2020, 09:50 PM
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Quote:
Originally Posted by Formulas View Post
As a data point was there any 1.77 exhaust valve heads with hardened seats ?
Yes the 7K3 heads and 7F6 heads we have done had induction hardened seats. The SD-455 heads came with an exhaust seat insert.

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Old 07-31-2020, 12:44 AM
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Don't think that I've seen a set of stock 96 heads that didn't have some recession going on. They did good and made it past 100,000 miles or so, but the party's over.

Not that much extra money just to go ahead and get it done.

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Old 07-31-2020, 04:26 AM
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Note that the factory hardening was not a separate seat of a different material that was pressed in. Factory hardened seats were either "flame hardened" or "induction hardened." The "flame" hardening was the first technique used, in '72 I believe. It didn't impart as much hardness into the seats so they went to the induction hardening.

Basically the factory used high heat to harden the metal in the heads at the exhaust seat. Once those seats start to wear, it makes sense to put new hardened seat inserts in.

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