SBC head ?

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88bluestar
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SBC head ?

Post by 88bluestar »

What 882 head castings were the thicker castings?

If that’s my only option, just want to make sure I’m looking for the right castings.
1980RS
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Re: SBC head ?

Post by 1980RS »

Older dated castings were always better.
mag2555
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Re: SBC head ?

Post by mag2555 »

The darn 882s are the first castings with hardened seats and are prone to cracking, so I would not lean on them too hard!
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88bluestar
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Re: SBC head ?

Post by 88bluestar »

Looking at 882 more likely for a back up engine. I have a set of 993 currently that I may use on the primary engine. 441 and 487 are hard to come by where I'm at.
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Re: SBC head ?

Post by F-BIRD'88 »

Look for #920 and #336 castings.
Pre'75 good heavier castings like 487. Not as popular but just as good. Don't have the funky exhaust port like a 882 or 462624.
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Re: SBC head ?

Post by NewbVetteGuy »

Are you thinking of the 882 heads vs. the 624 SMOG era heads? which were lightened / thinned versions of the 882 heads based upon what I've heard...

I had a set of 624 heads taken off with 14.6k miles on the engine and even with only 14.6k miles on them, they had a crack in one exhaust seat...
Like Class Action Lawsuit level of terrible. Not sure how GM avoided it on that one...

Part of me wonders how much the high temps and terribly retarded cam and ignition timing was responsible for the cracks and how much was the casting itself. My understanding is that it was the GOAL to pass some unburnt mixture into the exhaust and then get a 2nd burn from the heat, left over fuel, and oxygen injection ala the AIR pump -having a 2nd mini combustion event in between the exhaust valves and the CAT seems like it's bound to create problems.

Adam
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Re: SBC head ?

Post by jeff swisher »

My 624 casting heads did not have a funky exhaust port at all.
I have ported 2 sets of those 624 heads and they did well.
One set went on a 388 stroker I built for the father-in-law that engine ran for 15+ years and the other set were mine.
I put 60,000 miles on them and beat the snot out of them.. no issues.

The exhaust port looked nothing like the 882 heads. Now the 882 heads I had measured pretty large on the intake runners.
I want to say stock they were in the 170cc area.
88bluestar
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Re: SBC head ?

Post by 88bluestar »

So far what I have found with a 1.94 valves, is 993, and a set of 991. CAN NOT DO ANY PORTING.
I gather on a 3,000 lbs race car the 1.94 is better to compete with, and also keeping the valves from being sunk helps. Must have the stock appearing bowl cut. no blending.
88bluestar
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Re: SBC head ?

Post by 88bluestar »

Just measuring the cross section on them, the 993(1.94/1.50 valves) is just a bit bigger on the intake port entry then the 991(1.84/1.50 valves).
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Re: SBC head ?

Post by econo racer »

I have used the 993 heads for years, IMO a good head.
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