The Stovebolt Site Forums The Shop Area Engine Shop Need Help ID this engine

Hi all, I recently picked up an old V8 for next to nothing. I ran the engine casting numbers 3914678 and came up with either a 302/327/350. So which one is it? The Vin pad on the front of the block is blank. behind the flywheel there are a few other numbers (H30, 638, 678). what else can I use to decode my mystery engine?

How many main bolts does it have? That will narrow it down a bit. Also, check the stroke, as that will pretty much peg it right there, as the 302(unlikely), 327, and 350 (last are more likely) all have the same bore, but different strokes. The 302 has a 3" stroke, 327 is 3.25, and the 350 is 3.48.

If it doesn't have a place for the oil filter it is almost certainly a 1955. In 1969 was the introduction of 4-bolt mains. beginning in 1969 many small block engines did not have the number on the machined plate, as an anti theft measure it was moved to the rough cast area just above the oil filter. You are correct on the year models it could have come from. the reason I put the above is to let you know about what range it could have been. You can find out a world of info. in the "Chevy V-8 Engine Casting Numbers 1955-1993" book published by Amos Press Inc. It is compiled by the staff of "Cars&Parts Mag." I hope this will get you going in the right direction.

It was actually '68 for the 4 bolt mains, even then, it was only on the 302 and 350.

Well I tore into it today to get to the bottom of this mystery.


Head Casting numbers.
3927185, (307,327,350) (69-76) (1.72 / 1.5) 70cc
3986339X (307,350) (71) (1.72 / 1.5) 74cc

Crank Casting number
3932442 (267,305,350)

Based on what I found I would say its safe to say its a 350.

LONGBOX55, you may be right but my book says "The big news for 1969 small blocks was the introduction of four-bolt main bearing caps for high-performance and heavy-duty applications. 1969 was the last year for the popular 327 engine and the now-famous 302." Page 9 in the book I listed. But who knows, my book may be wrong.

My sources all show '68 for 4 bolt mains, it also lists that all 302 and 350 engines from '68-'71 are 4 bolt main. This is on Section 5, page 7 of the 1987 issue of the Chevrolet Power Catalog.

Chevrolet made Two 327 engines- small journal (early) large journal (late).
The 302 327 and 350 share the same 4" bore. So if you have a large journal block with a 4" bore you can build any of these engines with either 2 or 4 bolt mains. The 302 is the hardest to find cranks and Pistons for. A large journal 327 can be built using a 307 crank and 327 Pistons. One of my high school friends had a 67 Camero with a 350 from the factory.

My brother in law owned a 1967 Camaro with a factory RPO-Z28 302 engine, but I never remember anyone saying if it was a 2 or 4 bolt main???

Mike B

Weren't the failures of the high revving 2-bolt main in the 1967 302 the impetus for development of the large journal 4-bolt main?

I did not know you could make a 327 using the 307 crank and 327 pistons and rods. I might look at doing that as I would like to have a 327 in the old truck. I do wish it was a 4 bolt main.

A two bolt main block is more than adequate for street use unless you turn high rpm or haul heavy loads. Most passenger cars had two bolt main blocks and they performed very well.

BTW If you had a large journal 302 crank, put it in a 307 block with 283 Pistons viola large journal 283.
Small cubic inch and high rpms do not make make good street engines IMHO. A 383 small block stroker with vortec heads and a four barrel throttle body injection mild cam and small cap HEI would be the berries in any of these old trucks.
Just sayin'