I aquired a 77Z28 and was told that it had a 383 in it. The guy that I got it from was not the person that did the work on it so he was just passing on the information. I have known this guy for a while so he is telling me the truth on what he knows.

Anyway I am new to the Chevy world so I am trying to figure out how to tell if I really have a 383.

Any help will be greatly appreciated.

Thanks,
Steve

If it is internally balanced, there is really no way to tell by looking at it. If it is externally balanced you can look at the harmonic damper/balancer and if it is externally balanced there will be a weight on it. Meaning it will not be round (typically has a "raised" area). The only other way to tell would require some disassembly.

Besides what Royce said, you could pull a head and measure the stroke.

OR maybe you could get lucky and see a dimple on the oil pan where they had to increase clearance for the rear counterweight. That wouldn't tell you for sure, but would be an indication that a crank with larger counterweights was installed.

If it has the 400 balancer on it check the casting # on the back of the block.Could be a 383 (350 block 400 crank) or a 400.

That would be a 377 instead.

sorry, posted under wrong topic.

too bad you can't readily find those devices the NASCAR techs use to check the size of the Nextel Cup (that still don't sound right)engines- you screw it into the spark plug hole and crank it over, and it tells you how big that cylinder is by how much fluid it displaces.
besides that, if it doesn't have counterweights on the balancer and flywheel, you need to tear a head off and start measuring.

Thats what I thought. I was hoping I could get away without pulling a head off. Oh well Gives me an excuse to check the motor out really well.

Thanks for all the help,
Steve