Chevy 400 & Pontiac 400 differences.

[mongrot]

What are the main differences between a Chevy 400 & a Pontiac 400? Are the camshafts the same?

 

[26Troadster]

if i could post pics easy i would but i don't have time right now. the best i can do for you now is tell you to google pics of both motors.

 

[dmw56]

Everything is different. Not close to the same except bore and stroke.

 

[Torch]

Have you never seen smokey and the bandit?

 

[Torch]

A Pontiac 400 is a creature all it's own.
Pontiac have a fully machined combustion chamber with a shape no other engine has and it has it's own sound
The bottom end more resembles a ford 390 or dodge 383 than a chevy smallblock
interestingly though the Pontiac v8 although slightly larger in outside dimensions is lighter than the Chevy big block

And they sound nice if built right

http://www.youtube.com/watch?v=vTScvCWtB28


http://www.youtube.com/watch?v=6nc8sJweyrU&feature=endscreen
This is actually a "stock" cam running around 320 degrees duration and .520 lift the Ram Air IV cam.
it really kicks in around 1800 rpm and pulls hard to around 5500-6000
Funny thing is this car probably gets 15-18 mpg on the highway and is running maybe 8.5 or 9:1 compression on pump gas.

The 400 chevy though is no slouch it just doesn;t have as much iron in it.
I knew a guy who had a built 400 chevy in his c20 4x4 and I had built 460 in my f150 4x4 and I could BARELY beat him in a drag race. My truck felt more powerful than his but when we raced he was always right there.

 

[sgtpontiac]

Nothing similar or interchangeable ....

Ponitac motors are like olds and cad motors....big heavy torque monsters....if you were referring to a 400 small block chevy they are smaller physically and lighter by a couple hundred pounds...if you were referring to the big block chevy....396, 400, 402 (which by the way are pretty much the same motors) or the 454 then weight wise they are about the same but still nothing interchangeable....hope that helps...there are people who talk about using pontiac heads on their chevy small blocks...that's in reference to a design of head.....whole different kettle of fish....if that might be the reason for the question.....

 

[Dr Crankenstein]

What the guys said... but I feel it's only right to add some confusion...

General Motors of Canada used Chevy chassis and drivetrains in Pontiacs until 1970 and again from 77-86. In those examples, a "Pontiac" 400 is a Chevy motor and therefore identical. Lift the hood of those "late models" and you could find any number of GM engines, Buick, Chevy, Pontiac or an Olds diesel. (Try that one at your local parts store). Of course, GM also imported Pontiacs... Firechickens, Trans Ams, Tempests and GTO's... they have real Pontiac engines including the 400.

What was the question, again? [S

 

[sgtpontiac]

Should have known you'd bring that up!!! lol

What the guys said... but I feel it's only right to add some confusion...

General Motors of Canada used Chevy chassis and drivetrains in Pontiacs until 1970 and again from 77-86. In those examples, a "Pontiac" 400 is a Chevy motor and therefore identical. Lift the hood of those "late models" and you could find any number of GM engines, Buick, Chevy, Pontiac or an Olds diesel. (Try that one at your local parts store). Of course, GM also imported Pontiacs... Firechickens, Trans Ams, Tempests and GTO's... they have real Pontiac engines including the 400.

What was the question, again? [S

Cloud the issue with that "foreign" stuff.....a Pontiac on a Chevy Frame....Bah humbug....still a chevy...Parisiene...bah humbug....lol

 

[offroadrolls]

While we're here,

what was the 403 in I don't remember what year Trans Am, 79? 81?
Is it like the 402 BBC was to the 396 BBC? Same difference?

 

[sgtpontiac]

403 was an olds motor......

what was the 403 in I don't remember what year Trans Am, 79? 81?
Is it like the 402 BBC was to the 396 BBC? Same difference?

Another blunder on the part of GM....you simply can't put Olds motors in Pontiac's....its Sacrilegious ...like putting a chevy motor into a buick....I hated when GM made them all Corporate Motors....

 

[Old Iron]

Preach on Sarge.
I'm with ya, I'll do the repairs on the soap box

 

[sgtpontiac]

Sorry...I do tend to ramble....

Don't I???

 

[Old Iron]

Don't I???

[cl [P [P

 

[dmw56]

I put a Pontiac engine in an El Camino. [

 

[sgtpontiac]

I can live with that......

I put a Pontiac engine in an El Camino. [

Being a Ponitac Purist....you can put a Pontiac into whatever you desire....I'll find no issue with that...but 454's don't belong in a GTO or a Firebird or any other Ponitac.....nor do Olds, Cadillac or Buick motors....lol....
By the way...how did it run???

 

[Old Iron]

I put a Pontiac engine in an El Camino. [

Was it one of these

 

[fuzz]

40 coupe in my avatar had a 455 Pontiac in it. Torque monster.. weighed 3000 and ran 10.80

 

[Torch]

The 403 is an oldsmobile smallblock
Thinwall casting with windowed main webs.
Ok street engine...not so much for all out racing

you can build a 425 olds smallblock out of a diesel block with a 425bb crank and a little fancy machine work.
350 diesel blocks make good bottom ends for blower motors

you could drop a 350 diesel engine right in that transam and get 30 mpg lol

Actually I was going to do that with one of my birds before I sold the flock.

I was reported as having said "they all don't need to be fast do they"

I've had a couple 350 diesel engined rides... fast as a carbed 305... 18 mpg in town 30 on the highway

In my threads i have a 79 olds regency 98 brougham I'm eventually going to rebuild a 350 diesel for.
I found a low mileage spare engine with a broken head bolt. The one in the car had a prototype rod it sent to china.

 

[Torch]

Cam timing is important

A 400 chevy smallblock cam in a Pontiac 400 would be retarded
A 400 Pontiac cam in a small block Chevy would be advanced

 

[sgtpontiac]

I was going to say something here....

Cam timing is important

A 400 chevy smallblock cam in a Pontiac 400 would be retarded
A 400 Pontiac cam in a small block Chevy would be advanced

but after careful consideration, I will invoke my right to remain silent!!