I bought a car from a guy and he claims it is a 383. Is there any way to tell without tearing down the engine? He claims that it was just rebuilt. The car runs REALLY strong and I can tall it has new headers on it I have driven 350s and it seems to have more power. Is there a quick tell?

 

No

 

You can check the casting number to determine if it's a 305 or a 350 block.

The majority of 383's use an externally balanced crankshaft. This can be determined by seeing the offset in the harmonic balancer. If it's using an externally balanced crank, it can be a 334, 383 or 400.

If it was just recently rebuilt, ask for the receipts. It would have had machine work done to it. The machine shop will say what the specs of the engine are.

 

what do you mean by the offset? Does anyone have a picture of what it would look like?

 

It will look like a chunk taken out of the balancer instead of being smooth all the way around.

 

Drop the pan. Casting number is on crank. Must be 350 block also.
Would need line boring and .030 over. Reciepts?

 

I doesn't have to be externally balanced to be a 383. I built my 383 and it is enternally balanced. There is no way you can look at mine and tell if it's a stroker or not. There is no real way to tell if yours is either. What size carb do you have? Does the engine lope? The reason I ask is if its got a smooth idle and a 750 carb and it runs really hard it's possible its a stroker.

 

Thank you Apeiron!
Everyone see the motor pictured?Looks like a 383 stroker doesn't it?


Well its not.A 383 stroker would look the same but,unless you or someone you personnally know built the engine there is no telling without a disassembly what is truly in your engine.
BTW,the engine pictured is mine and its just a standard bore l98 with 87 corvette heads.

 

If he had it built and doesn't have receipts - that would make me go Hummm?
But, being a possibility I'd ask how much is it over bored, what type of piston specifically the compression height and I'd ask if the rod is 5.7", 6", and what block mods were done. If he can't answer those I would definitely find out what it actually is.
Mine looks like the picture above, but is a 388/3.63Liter:

1. 4.06" Forged 1-1/8" compression high, -16cc D-dished pistons.
2. 6" rods
3. 3.75" crank
4. Motown 350 race block - stroker clearanced - bored 60 over.

 

The 383 will have a 350 block and a 400 flywheel since the crank comes from a 400. This means that it will have to either have a 400 flywheel or a bolt-on balancing plate. The flywheel will have a counterweight on it. I think that's right.

 

30 years ago you could assume that was true, but not anymore. There are lots of internally balanced 383s out there that are completely indistinguishable from a 350 without taking it apart.

 

exactly.
my motor is a factory 350 block with a 4" stroke crank (408"), internally balanced, from the outside, it could pass as a 305, 350, 383, ect.
unless the guy has some paper work from the work done, there is no way to tell.

 

i would imagine that if you pulled a plug and had a a volumetric vacum gauge and crank it to bdc on the power stroke, you could compare to a 350. how do they govern the circle burners with cube limits? i guess they just tear them down if you win?

 

You can have several engines of wildly different displacement that all have the same readings on a vacuum or compression gauge.

Racing engines are either homologated, certified when they're built, or torn down and inspected.

 

if its a 383 it should have an 8in balancer than the 6in on a 350

 

Unless the 350 has an 8" balancer, or the 383 has a 6", or any other combination.

 

currently i have a 305 i have an 383 rpm performer late model 425 horse carbarated i want to use the tbi on the 305 how much modifications will i have to do to make this happen

 

uh what....