Dual quads

[Cliff Ruggles]

I build scores of Pontiac engines here and drag race/sponser half a dozen of them out of our shop.

To date I've never touched a 326 or 350 for "high performance" use.  The bore is simply too small, and they are long stroke with heavy rods.  Cranks are basically the same parameters as a 400 but it makes little sense to start throwing money into a 350 build and piston choices are very limited for them, so you immediately have to buy expensive aftermarket custom made units.

Going that direction it just makes more sense to come up with a LOT more CID from a 400 block, and you can use the big 2.11/1.77 valves without clearance issues with high lift camshafts smacking the block.

I'm not saying a 350 Pontiac is a "door stop", but it takes as much as or more money to build one up and you get LESS of everything at the end of the journey, so why not put the funds into a 400 block right to start with?.......Cliff

[chance]

Ok, so if I understand you correctly  the 350 crank is the  same as the 400?  I have a 400 block but the crank is wasted. Rods are good pistons are garbage 8 valve relief units. So I can use the 350 crank, 400 rods,  buy some dome pistons to get the compression up for the 4x heads you give me a cam grind that you think best and we're good to go right? Or am I still on the short bus...lol
Thanks bud!
God bless!!!

[Cliff Ruggles]

The cranks are only the same for dimensions, they 350 would have used lighter pistons so unlikely it's balanced the same as a 400 crank.  Not a big deal if you are getting the spinning assembly balanced but something to keep in mind when using a 350 crank in a 400 build.......

[chance]

Ok, Thanks! How far can you turn one of those cast cranks safely? If my 400 crank was forged I turn it and use it. I've turned my Mopar cranks as much as .050 on the mains and turned them 6500 rpm and never had a problem. Like I said before I don't know Pontiac's.....Yet....LOL. You're going to fix that right??
Thanks again for your time my friend.
Take care!!
God Bless!!!

P. S. How are those grand kids doing?

[Cliff Ruggles]

The early "N" cranks are tough as nails and you can turn them clear down to BBC or even SBC journal sizes if needed.

I avoid the later "PMI" cranks as they are just not that tough and have seen enough issues with them to avoid them altogether, same with the 1975 and later 400 blocks unless it was a T/A 4 speed.....Cliff

[chance]

The 400 block I have is a 71, the car originally came with a 301. the guy i got the car from didn't know anything about the car or engines so someone put it in there before he got it. So is there an N cast into the crank I should  be looking for or a special number to Identify the crank?

Thanks!
Take care!!
God Bless!!!

[Cliff Ruggles]

Most of the nodular cranks I've seen have a huge "N" cast into them.  It can also be identified by researching the casting number on it.....Cliff

[chance]

Hello my friend. Hope all is well with you and yours. Since our last talk I've identified the crank i pulled out of the 400 and it's a 350 crank. maybe that's why it tore itself apart in such a short time??? Anyway I picked up a set of 061 big valve heads with 72cc CC , which are better than the 4x units i have. So I should't have to go with dome pistons after all. flat tops should be adequate. Should I get a 400 crank vs turning the 350 crank? cost wise it seem to be with in 100 bucks of just replacing it.
Thanks for your time!!
Have a Merry Christmas and a Happy New Year!!
God Bless!!!   

[Cliff Ruggles]

The crankshafts are the same dimensions, just different balance.  Replacing it would depend on if it needs heavy metal added to work with a 400 spinning assembly.

CC the 061 heads they may have small enough chambers you don't need a domed piston in it.  I do NOT like or used domed pistons in Pontiac engines, they work much better with flat top pistons due to the flat chamber floors, machined chambers, and 30 degree intake seats.....Cliff

[chance]

OK thank you! The 350 crank is grooved pretty deep so I'll be making even lighter than it already is. sounds like I better get another crank. Thanks for the info....as always your the man...LOL
Take care!
God Bless!!