hey all. hope i dont offend anyone here but my bro just bought a 69 firebird with a "built" 428 per the seller & was told it needed a valve job & rocker arm. turns out when he tore the motor down, one piston was laying in the oil pan & part of the cam. he later found a complete "fresh" 400 pontiac motor from a guy & turns out the cylinders are full of water & its a 350 pontiac. i once heard that all pontiac v8's from 350-455ci are the same block & only the stroke changes per cubic inch. if this is true, can the 350 pontiac block be bored to the same size as a 400, 428, 455? please dont laugh, i have no pontiac experience!! lol! i am trying to get him to convert to sbc or bbc but he wants it to stay pontiac. any thought? thanks for the help!!! bill.

Come On Guys, Throw Me A Bone Here!!

so all the blocks are the same size on the outside (326-455), this is true

but he may not be able to bore it out to a 400, i have read a lot about this
and from what i understand, the factory only made the cylinder walls thick as they needed to. which means that it would not be likely that he could bore it out to a 400

the 350's bore is 3.8750" and the 400 is 4.120, same stroke 3.75
that would mean that he would need to have .245" to spare in the cylinder walls, and it doesnt seem likely

i have a close friend who is looking to sell his pontiac block (and 69 bird),
i am sure is a 400 and we could look up the casting #s for you to prove it, and it has been magged, so it good, just needs some machine work

Hi Bill, we still build at least 10 Pontiacs a year and the blocks are all separate castings. This includes the 350, the 389, the 400, the 421, the 428, and the 455. There were none cast in a group. We do these for the resto guys. Your brother is probably is wise to keep it original, but that depend on many variables. For instance, how much of the car is still original?

Keep in mind, these are all fairly "thin" castings, the blocks are reasonably light-weight for their size.

If he stays Pontiac just find a 400 or 455, these are still around. Eagle does have a stroker crank for the 400 casting and can turn it into a 466". The one we recently built made 400+ HP with a 9:1 C.R. and ALL the factory components, Q-jet carb, cast intake, and exhaust manifolds. No HP chasing at all.

I have an number of my own personal customers who will NOT change to the Chev. Having sadi that, I also do have a 377 SB in a '68 Firebird runs out of Bristol, TN. Very happy with this combo. Thanks, Gary in N.Y.

P.S. I would let your brother make his own decision, he's the one has to "run" with it in the end!

What's wrong with the shelled block? Sometimes a shelled motor's block is still good so have him check and see b/c if it is still OK, then use it..

And if there is nothing structurally wrong with it, I would stroke it like Gary said.

pdq67

the outside lower portion of 2 cylinders are opened up from the rod smacking them. absolutely not fixable. he's not trying to keep the car all original like matching #'s, just all pontiac. so if anybody knows of a good pontiac build please list the specs. he's trying to run mid to high 11's on the motor & squirt it a little to dip in the 10's. thanks, bill.

the outside lower portion of 2 cylinders are opened up from the rod smacking them. absolutely not fixable. he's not trying to keep the car all original like matching #'s, just all pontiac. so if anybody knows of a good pontiac build please list the specs. he's trying to run mid to high 11's on the motor & squirt it a little to dip in the 10's. thanks, bill.


Can cly sleeves still be set? Best way I know of is rebore and leaving a step at bottom to retain sleeve there as well as top of block. Is that portion damaged?

there are 1" holes on the bottom of the cylinders near the pan rail. i am 99.9% sure there is not a fix for it. just need a good block at a minimum & try to salvage parts from the other 2 motors.

As has already been said, you can't bore a Poncho 350 out to be a 400.

In California, you could talk to Ken (Ace) Brewer. His website is: http://www.pacificperformanceracing.com/index.html

As an aside, you may want to avoid a company called Rock and Roll Engineering as he doesn't have the best reputation with Pontiac folks.

Hope this helps some.

Cheers,
Ken

The fastest Pontiacs in the country that hold mant stocker class records come from Parsons and Myers in Dayton,O.

A very good Pontiac forum with lots of info on the classic Poncho V8:

http://forums.performanceyears.com/forums/

Nothing wrong with transplants. I've been dropping Pontiac 455s into Chevies for years. :D

As has already been said, you can't bore a Poncho 350 out to be a 400.

In California, you could talk to Ken (Ace) Brewer. His website is: http://www.pacificperformanceracing.com/index.html

As an aside, you may want to avoid a company called Rock and Roll Engineering as he doesn't have the best reputation with Pontiac folks.

Hope this helps some.

Cheers,
Ken

Very good advise. Ken Brewer has an excellent rep in the Pontiac community. R&R does not. FWIW, you can bore out a 389 to 400 or a 421 to 428. (Both would be 60 over) But as others have posted, no 350 to 400, etc.

i second that advice
http://forums.performanceyears.com/forums/
is an excellent tool for learning about the pontiac motors. all pontiac block are "midsize" blocks that all have the same external dimensions. at a glance a 326 and a 455 look exactly the same.

A very good Pontiac forum with lots of info on the classic Poncho V8:

http://forums.performanceyears.com/forums/

Nothing wrong with transplants. I've been dropping Pontiac 455s into Chevies for years. :D

thanks for the info guys!! huge help!!!!!!!!

You might check out this guys site. He builds Pontiac motors for lotsa people and has an excellent rep http://www.angelfire.com/fl4/pontiacdude428/kensspeedandmachineshop.html