400 heads without the front exhaust manifold holes?
 

What the heck. Do i have to track down an origional exhaust manifold for this head? I think its a 7j2 casting. This motor is a runner, just to install on my lemans so i can cruise this spring/summer while i rebuild my 455. I need some insight. thanks.

'72 heads are like that. No outer exhaust bolt holes. Don't need to worry about it unless you are running headers. Just put the 4 bolts in normally.

can u use any exhaust manifolds? i dont have the origionals to theses heads.
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Yes you can.

Some one was making adaptors for installing headers or non 72 manifolds with the outer bolt holes. But I can not seem to remember who, or find them on a google search.

But they used angle brackets that bolted to the block and had the required stud attched to them.

Maybe someone else can remember who made them.

I was going to use them, but then decided to use a differnt set of heads that I had that had the outer holes.

Paul Spott sold them.

You can make your own with some angle steel and some bolts/nuts.

Do a search on them.

:)

I really would like know what Pontiac was thinking when they did that. I'm not an engineer, but WTF!!! It doesn't even make sense, and is certainly counter intuitive. Ok, even if they didn't drill them....but to eliminate the boss totally? :doh:

Time is money. 300,000 units minus 4 drilled and tapped holes each, equals 1.2 million less processes.

Pontiac Dude has the adapters.

Ok, but they altered the casting, then put it back.... What did that cost? I'm ok with not drilling, we can drill them ourselves. They must have posed a problem to Pontiac also, cause they either stopped using that vendor, or revised the architecture. Bottom line is; they returned!

Yep. Just use the regular manifolds. As has been said, you can drill the heads. The hole will go into the head bolt hole. No biggie. Use a stud with some hi-temp LocTite.

http://www.crankshaftcoalition.com/w..._HEADERS_2.jpg

My understanding is the outer bolts were eliminated to prevent use of headers. 1970 Clean Air act et all.

I doubt it since not all heads were done this way. And shortly thereafter, when the heads were reduced to 4X and 6X the bosses AND holes were back. And what about the other brands? I would chalk it up to bean counting which is probably worse than anything in the Clean Air Act.

^^ Good point about bean counters. Perhaps it was both. Anyone know if factory manifolds mated to these heads also lacked the outer bolt holes?

Factory manifolds lacked the bolt holes too:

http://www.slyagent.com/72Lemans/neng8-exh1.jpg

http://www.slyagent.com/71cat/cp1-enginecomp.jpg

i had a '71 the car was untouched and fine, but massive exhaust leaks right there. That car had #96 heads which were drilled but the manifolds were not provisioned for bolts. A set of Dougs fixed that.

about "holes" and what they cost: tons of engines were built with holes drilled and tapped for 4 bolt mains that they were never gonna get, right? I know that stopped along with the outer exhaust holes.

The warranty claims for exhaust leaks might have caused them to reconsider?

Idiots! What's next cast rods?