The Stovebolt Site Forums The Shop Area Engine Shop Small Block Chevy motor ID

Anybody have the short version of how to tell the difference between small block chevy engines? 400 vs 350 vs 327 vs 305? I have located a '79 truck that I'm going strip next weekend that is supposed to have a 350 in it and I want to verify that it is indeed a 350 before I go to all the trouble to pull it out of the truck and start the rebuild process. Since the guy I'm getting the truck from is family I would normally trust what he said was in the truck, but this one was picked up at an auction after some kid rolled it so he hasn't driven it or turned any wrenches on it and is only going by the information that was available when he bought it. I don't expect that it will have "This is a 350" emblazoned on the valve covers.

Here ya go:
Chevy V8 decoding

Visually there is no way to determine if you are looking at a 305, 307, 327, or 350. The only sure way is to get the engine code/suffix that is stamped on the land area just forward of the right hand (passenger) cylinder bank. The links provided by the others here are decoders which will tell you what size the engine block "should" be.

One method to tell if you are looking at a 2 bolt or 4 bolt engine without dropping the oil pan is to see if there is a small pipe plug on the block behind the water pump. If the plug is there you more than likely have a 4 bolt block.

Thanks guys.

The freeze plug thing is not a hard and fast rule. There are some exceptions...although I can't remember them off the top of my head. It's true in most cases, tho.

However, the dead giveaway (or good news, depending on how you look at it) is the asymmetrical harmonic balancer on the 400. They're externally balanced motors so the balancer and flexplate/flywheel have the balancing weights rather than the crankshaft.

Usually the number right behind the distributor,drivers side,if the last 3 numbers are 010,it's a 350.

Well, my original assumption was incorrect...there was a sticker on both valve covers that said "Target Master 350 - General Motors Parts Division". Now I have another question...is this an aftermarket "crate motor" from GM or was this the original motor that came in a '79 Silverado? I looked up the casting number using the handy information above and it checks out as a 77 - 79 350 with either 2 or 4 bolt mains, but the stickers on the valve covers are sort of curious.

Well I have a couple sets of those same valve covers and I can imagine being happy to swap them straight up for some other designs.

So maybe smeone wanted whatever used to be on this motor and traded?

Or someone put these valve covers on to sell the motor as a Target Master?

I've no idea what casting numbers are common on Target Master motors. Anyone know?