[chevelle4542speed]

my little brother has a cutlass 70. the motor we think is a 350 but i swear it look likie a big block. on a small block the exhaust on the heads are flat but on this motor thay ccome out like a bb. but the vavle covers are small like a sb. this is in a 68 lemans too and it says its a 350. why do these block look like this are they a performer. hi perf parts avaible or just drop a regular chevy 350 in it??

[astroracer]

Back in "the day" GM divisions had their own engine line-ups. Oldsmobiles had Oldsmobile motors as was the same with Pontiac, Cadillac and Buick. Oldsmobile, Buick and Pontiac "350's" were basically the same block as the larger displacement "400" and "455" motors. Chevrolet 350's (small blocks) are a completely different block as compared to the Chevrolet "Big Blocks".
What you are looking at in your Olds and Pontiac are real Oldsmobile and Pontiac motors. Not the generic "Corporate" smallblock that started showing up in all lines by the mid to late 70's...
There is a ton of go fast parts available for your motors. Do a few searches for Oldsmobile or Pontiac performance parts.
Mark

[454C10]

From my experience, the Olds 350 seems to make more torque than a chevy 350. So, I feel the Olds motor is better for a heavy car (like a 70 cutlass). I helped do a chevy 350 conversion in a 70 cutlass and the Olds 350 engine moved the car much better than the chevy. However, i would pull the Olds 350 and drop in an Olds 455 since they are the same size externally.

[jimfulco]

An Olds 455 is bigger externally than an Olds 350. Motor mounts are in the same position, but the deck is higher on the 455. Pontiacs are the ones that are the same size.

[Hippie]

Originally Posted by jimfulco

An Olds 455 is bigger externally than an Olds 350. Motor mounts are in the same position, but the deck is higher on the 455. Pontiacs are the ones that are the same size.

Yep and I wouldn't be so quick to ditch the Olds 350, couple of my friends had them back in the day. One was a factory Hi Perf piece and the other was built up from a base 2 bbl. engine both were in '68 Cutlass Hdtps. with 3.90 gears, one was a 2 speed automatic ( Olds called it a Super Turbine 300 not a Powerglide IIRC ) and the other a 4 speed and they were both very strong runners. For serious performance work the earlier 330 had the same stroke and journal sizes and used a forged steel crank. The later Olds 403 is the same deck height and has the best rods plus there is a ton of performance goodies available for the "short deck" Olds motors. Same performance parts for a Pontiac 400 will fit the 350 except pistons but the 400's were so easy to find that most people didn't mess with the 350's but they can pack a wallup too. All 4 of the GM 350's had performance potential but the B-O-P 350's were overshadowed by their 400 CID and larger siblings.