Which is better engine combination, 383 4bbl or 400 4bbl

[borninamopar]

Originally Posted by Chris Hill

What do you think is the better engine combination to build a 71 383 4bbl or 72 400 4bbl?

CID383400Factored HP299298Ship weight low11.7812.01Ship weight high12.1712.01Adv CR9.68.79Deck0.0190.075Gasket0.0210.02Head CC79.582Bore4.254.34Stroke3.3753.38Actual Compression9.848.8Fact hp/cid0.780.75

By memory, the 383 has smaller carb and better flowing heads. I think the intake is a push. Both have the same camshaft and valve sizes.

The big difference is the 383 has 17 less cubic inches and 1 point more of compression. My gut says it would be a push as both combinations done equally well would make within 5 hp of each other.

So what do you think?

I would think based on my one brain cell, (without checking the books)
That the 71 383 engines came with a small holley and the 72 400 came with the big Thermobog. I didn't check the weights, but I believe the 400 reciprocating weight was heavier, and therefor I believe the 383 would get into the sweet spot much quicker. I have built both engines (383 and 400) and the 383 always spun quicker. Revved like a small block. The 400 is a good build if you could up the compression because of the large bore. And with the forged crank it can be spun really high. Big blocks that act like small blocks. Gotta love 'em.

[JRyan]

Well, being as there is only a 15 gram difference in piston weight and an 18 gram differential in the NHRA accepted weights, I doubt that in STOCK, reciprocating weight has anything to do with whether one will rev quicker than the other. In SUPERSTOCK, it's a moot point as you can make it as light as you dare.

Personally, I'd take the 400.

Jerry

[GTX JOHN]

We have raced both over the years.......we now (Robbies Roadrunner) run 400 combo. Do not see a lot of flow difference between 906 and 452/346 Heads. BIG difference between small AVS and large thermoquad (really any thermoquad) that is legal on 400. I have never seen a 400 combo that is not FAST from start! I have seen quite a few 383's that the guys have struggled with, although I know a purple '70 383 that is real fast up north. Let me know if I can help on either one. Racer7411@yahoo.com