I HEARD THAT ON A 80 81 CAMARO V8 THAT IF THE DIS. WAS ON THE BACK OF THE BLOCK ITS A 400 NOT A 350
OR HOW CAN U TELL THE DIFFERENCE? THANKS

I have a list of casting numbers that will tell you if it is a 400 or a 350. What is the casting number of your block? Look at the front, if you can, just near where the camshaft inserts (under the timing cover).

Ok, here it is. Basically, if your casting number is one of these, then it IS a 400:

3951511 (4 bolt main 1970-1973)
3951509 or
3030817 (2 bolt main 1974-1976)

Hope this helps

Go to www.mortec.com (http://www.mortec.com) without a doubt the best source of casting number info, and lots of other good stuff also.

Hey
A quick way to tell the difference beetween a 400 and a 350(chevy of course) is that 400s have 3 freeze plugs on either side of the block, while other small blocks have only 2.
Peace
Joshua

Many (but not all) have three freeze plugs per side on the block versus two for the 350. I've had three 400's and none of them had three freeze plugs per side (although there was a raised casting area for a third one).

A 400 never came stock in that car so unless it was swapped it's not a 400. All the standard 350's and 400's have the rear mounted distributor (except late-model LT1's and LS-1's).

Jody

another way to tell is the harmonic balancer will be taller and almost a 1/4 inch will be milled of almost half way around the balancer and another way is on the side of the block the cylinders will be a little swollen if it is a 400 as the later 400's only had 2 freeze plugs

Also, if you have the engine out or party disassembled enough to see the casting numbers, then you may likely have a cylinder head off too. If so, look for the presence of steamholes between the cylinders as opposed to a water jacket. The cylinders will be visibly closer together too.