biddlesticks

I have the option of re building an olds 350 or a 403 does any one have any sugestions on witch one. its going in a 66 cutless that i plan to drive as much as i can.

Redog

What year 350?

Not that 403's are made of mush, but the 1968-1972 350's are very strong.

Don't know if it's 73 or 77 and up use windowed mains with less dense metal for the block

olds 307 and 403

Budget? Power expectations?

ThePackRat

1976 was the last year for the solid webs.

And yes budget & expectations would be a good place to start.

Eightupman

Being that I just built a 403 twice, and I'm well aware that a good crank is difficult to find (a 403 crank is only a 403 crank, 350 cranks are not the same) and good pistons are more expensive than 350 (or 455) pistons, as well as the gasket kit,the 403 was more difficult to build. You will battle overheat issues if you are not meticulous with the build. Please bear in mind I am in NO WAY knocking the potential of a 403 motor. With just the sheer number of 350 motors still out there.. I'm saying go 350, and save the 403 for after you learn the ins and outs of how different a 403 really is.

John

olds 307 and 403

John, I assume you mean balance wise, for the crank. I agree on the 403 being harder to cool. The 68-76 350 is a great motor but the 403 has a definite torque advantage with similar mileage.

J-(Chicago)

I have a 350 motor here that needs some love if you are near chicago.

Redog

How much more torque does the 403 have over the 350? I know the 403 uses very large combusion chambers in the heads. 83cc IIRC

Could be a good and bad thing I guess.

IMHO, I would stick with the 350. I didn't know about the cooling issues with the 403, plus if you want a 330 crank for it (forged) there is a guy on my local CL selling a 330 crank and some other things for $500

Eightupman

Yes, I do mean balance wise, but didn't think it was wise to toss out too many variables as I don't know what the OP knows and doesn't know about building Olds motors. There is a grove on the front weight of the 403 crank that isn't on any 350 crank. I can only ASSUME that is where the meat is removed for the balancing to compensate for the heavier pistons. I assume this because the casting number of the 403 and later model 350 cranks are the same.

John

biddlesticks

Thanks everyone. the 350 is a 72 and it sounds like i will go with that one. my budget is pretty slim, im new at the engine side of things and i am planing to make it a daily driver. the availability of parts is also apealing.