Originally Posted by Tracker1 (Post 1383916)

-When you ordered a 400 Firebird, you got the base 400 at 330 horses with the #16 casting heads.

-Then you could order a 400 HO which used the high-flow exhaust manifolds from the next-rung-up 400 Ram Air engine and the hotter cam for the manual trans car. Everything else stayed the same as base 400. Closed air cleaner, closed hood scoops.

-Then the 400 Ram Air Engine had the special exhaust manifolds, and different heads, casting 31, with swirl polished valves and special valve springs, for higher RPM operation. And, of course, the foam air cleaner element that mated to OPEN hood scoops.

-In April 1968, came the first "round port" Pontiac engine. The nasty b#*ch Ram Air II (even though Pontiac never used Ram Air I as a designator for their 400 Ram Air) This was a very special engine with completely re-engineered heads with round exhaust ports, forged aluminum pistons (versus cast of the other 400s), special crank, special 4-bolt block, re-balanced Armasteel crank etc. Foam element air cleaner, open hood scoops. A beast in a Firebird.

Originally Posted by Astock (Post 1383918)

So, it took until 1968 1/2 for Pontiac to finally build an equivalent to the L78 thats been around since 1965.

Originally Posted by auwrestling (Post 1383919)

Also add that the 68 RAI Firebird had four bolt main cap 400 block!

Originally Posted by 1967Z28 (Post 1383920)

Thanks for the info. Where all the 400 engines available from the start of '68 production except the RAII?

I think any RAII would smoke an L78 and I am a Chevy guy.