400 cid Engine

[JKhuskers]

I am new to this forum and know very little about pontiacs. I want to build a project car and put a 6.6L engine in it. I eventually want to get as much power as possible, so I want to start with the right engine. I am currently looking for a 400 and have found several on the internet. The question I have is a 400 that is found in a '68 Catalina have a different block or heads than that of a '76 Trans Am? I had a '76 Trans Am and didn't appreciate it back in the day, want to try again and do it right. Thanks in advance for any help.
JKHuskers

[MagicRat]

Originally Posted by JKhuskers

I had a '76 Trans Am and didn't appreciate it back in the day,

Welcome to the forum.
I did the same thing.... a 4spd/400 1977 Trans Am, a bit rusty, but saveable and I just let it go

One of the other members here, MrPbody seems to know more about building fast Pontiacs than anyone else on the planet.
He should be able to provide excellent advice very soon.

[MrPbody]

JK,

Here I am, right on "que"... (:-

There are three basic "flavors" of 400 block. '67-'69, has two mounting holes on each side for the motor mounts to attach. No provisions for any more. Good block for performance builds.

'70-'75 (or so..) has 5 mounting holes drilled and tapped, on each side. This block will "fit" in any Pontiac application. VERY good block. Considered the "best one" by most. Last three digits of the casting number are "988".

Mid-'75-'79 has three mounting holes drilled and tapped. One side of the block has provisions for the other two, but not drilled. This block is the "weak" one. For builds up to 500 or so HP, it's fine. Beyond that, it's risky. Last three digits are "557". The main bulkheads are considered "defficient" for higher levels of power.

A few of the "557" blocks were cast using the older molds, and installed in '78 and '79 T/As with "T/A 6.6" packages. Those blocks have the heavier main bulkheads, and are fine for upwards of 700-750 HP. They're easily recognized by the "XX" on the front pad (engine code) and the "XX" cast into the valley area.

The '76 T/A calls for the "3-bolt mount". The middle-years block is the best one and easiest to find.

I would advise buying Jim Hand's book "How to Build Max-performance Pontiac V8s" published by SA Designs. This is the only CURRENT study of the ol' Injun (Pontiacs are affectionately refered to as the "Injun Engine"). The book is based on building a high performance STREET eninge, and doesn't have a whole lot of "race" info in it. Not to worry. You wanna get folks riled? Build the Pontiac! IMO, not a better STREET-performance engine out there.

What is VERY popular today, is building a 461 or 467 CID engine from the 400 block. We (CVMS) use the Eagle "stroker" kit for this. It effectively turns your 400 into a 455, without the weakness of the 455. With iron heads, we routinely make 550 HP and 600 lbs. of torque on 93 octane gas, with enough vacuum for accessories. With aftermarket aluminum heads, 650 isn't out of the question, and still "streetable".

Jim