1971 firebird motor

[bird71]

I bought a 1971 firdbird with a 400 pontiac motor is this a big block or small block ?

Keith

[Kevin - Blown 95 TA]

Try F-Body org and go to the first gen sites. there isn't that many guys here who can answer 1st gen questions, although I think it was a small block - let us know what you find out.

[Bojangles1432]

Yes a 400 is a small block. 400 = 4.125" x 3.760"

[Jeff_in_Atl]

I fully admit I don't know squat about this but I thought the Pontiac 400 was the same block as the 455 and was a big block and the Chevy 400 was a small block based on the 350 chevy motor.

[81turboman]

From my knowledge from my father, the race track and everywhere else i have learned here is what I know.
1. All early model pontiac V8's are considered big blocks.
2. They are all based on one block size.
3. The only difference is the bore and stroke.
I have 2 400 blocks and 2 301's. According to every true pontiac man I have ever talked to they are all big blocks
Anything from 301 to the 632.

PS If you need parts check out
*Ames Performance Engineering
*Classic Industries
* The Paddock
*Year One

Glad to help, be interested to see the car!!

[Kevin - Blown 95 TA]

Originally posted by Jeff 95 Z28
I fully admit I don't know squat about this but I thought the Pontiac 400 was the same block as the 455 and was a big block and the Chevy 400 was a small block based on the 350 chevy motor.

Now that you mention it, I remember this being the case too - but it was a LONG time ago that I read about it.

[N20LT4Bird]

Originally posted by 81turboman
From my knowledge from my father, the race track and everywhere else i have learned here is what I know.
1. All early model pontiac V8's are considered big blocks.
2. They are all based on one block size.
3. The only difference is the bore and stroke.
I have 2 400 blocks and 2 301's. According to every true pontiac man I have ever talked to they are all big blocks
Anything from 301 to the 632.

PS If you need parts check out
*Ames Performance Engineering
*Classic Industries
* The Paddock
*Year One

Glad to help, be interested to see the car!!

I have never used the term big block, small block when it comes to Pontiacs. Its just a PONTIAC motor. Chevy uses this term to designated the different blocks they used (depending on the angle of the V). Pontiac only has one block. So, you could argue they are all small blocks too right??

[Jeff_in_Atl]

"I have never used the term big block, small block when it comes to Pontiacs. Its just a PONTIAC motor. Chevy uses this term to designated the different blocks they used (depending on the angle of the V). Pontiac only has one block. So, you could argue they are all small blocks too right??"

Good point! LOL

I just figured anything that went up to 455 would be called a big block.

Dodge has a small block and a big block.
AMC only had 1 block.
The worst case is with Ford.
260, 289, 302, 351W small block
351M, 400M small-medium block
351C, 360, 390, 428 Medium block
427 medium-big block
429, 460 big block.
Jeez