I just picked up a chevy 350 sbc which is supposedly a 383 built for 1/4 mile drags. Attached is a demon 4 barrel edelbrock tall spacer and air cleaner/valvecovers, along with the alt etc. i have nothing in this engine but my time, I got it in a trade for some labor. I pulled the 383 out of my z28 and threw this "383" in with my buddy yesterday. A lot of power and there's definately some kind of modification here.

I looked up the suffix, cast, partial vin, etc andI beleive it's a chevy 350 out of a 77 truck. 4 bolt main I beleive. 20 nickel cast.

I need to determine what has been done to this engine and verify its authenticity as a 383. Any help or suggestions are appreciated.

 

If the casting is for a 4" bore block, then a 0.030" overbore with a 400 stroke crank will make it a 383.

Since a 400 crank is externally balanced, it will have an externally balanced dampener and flexplate/flywheel. If both are neutral balanced then it's a good chance it's just a 350 or a 350 with an overbore.

The only way to be 100% sure of the displacement is to pull the head and measure the bore and stoke.

As for what it was originally from, it doesn't matter. It's now a 4" bore block that's been rebuilt and modified. If you have a suffix code then pinpointing the original type of vehicle would help but would mean nothing.

 

Or it could have a aftermarket internal balance stroker crank that uses non 400 parts
only way to know would be to drop the pan and see if any #'s stamped / cast on the crank

 

I dropped the pan but didn't see much other then the fact that it looks newish inside. Minimal wear, possible recent rebuild or build.

 

Well if you've gone that far, get the casting number off the crank.

 

you can also check to see if the block has been ground for the clearance of the crank, 400 crank wont turn unless the block is ground for it

 

I believe it needs t be ground for the rods to clear as well

 

The 400 crank mains need to be turned down to fit into the 350's block. You won't see anything just by looking at it.

 

sorry this is not all true, an aftermarket 400 crank can be bought with 350 mains and the only thing that has to be done is ground the block or the throws and the rod bolts to clear!