Just got a 74 el camino, the VIN says that it should have a 400 in it but the decals on the fenders and the guy i bought it from said 350. Took just about everything out of it till i found the engine id code, but the problem is im pretty sure whats in it aint what it rolled out with originally. So can Ya'll help? the codes on the block are: 16J185325 and V1205CMJ please help. Thanks alot

try this site.

http://www.mortec.com/castnum.htm

The 1974 VIN shows the engine code:
The 5th symbol in the VIN - D=250 cid, H=350-145hp, L=350-160hp, R=400-150hp, U=400-180hp and Y=454-235hp.

I also own a 1974 Elky. The easiest way to ID a 400 I was told was to look at the harmonic balancer. The 400 is the only small block chevy that is externally balanaced and has a different flywheel that is notched. I guess its possible it could be a 350 block with a 400 crank making it a 383.

Look at this ad and it might help

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33616&item=7949064090&rd=1

I'll try and snap some pics of mine possibly. I've got a 74 SS with the factory 400 2 barrel combo