This may be a dumb question, but is there any way to identify from casting numbers on the block and/or heads what engine you have, i.e. is it an L69, LG4, L03 or LB9?

 

The casting number from the rear deck gives a good indication as to what engine you have in terms of the fact that the block was made from such and such to such and such years, the bore is x.xxx".

As far as the heads go, certain heads were only available with certain combinations, such as the "187" heads only came on 305 TBI heads, 416/601 heads only came on early LG4/L69 engines, and 081 heads only came on 305 TPI's.

Combine all that with what the top end looks like.

Put 2 and 2 together and you can get a pretty good idea of what you've got.

 

The L03 you can tell apart, because it will have the 187 swirl-port heads.

The L69, LB9 and LG4 have the same blocks and heads.

Early LG4s had dished pistons; L69 and LB9 have flat-tops. LG4s had flat-tops starting in about 86 IIRC.

Beyond that, the only way to tell would be the stamping code. But, if the block, heads, and pistons are all the same in the years you're interested in, the only other difference would be the cam; which you'd replace anyway. So it's a piece of information that's hardly worth the trouble of obtaining. The parts are good at face value, regardless of the engine "code".

 

Hmm maybe I'll give some more info. The motor is out of my friend's 87 IROC. But we're not sure if it's the original motor. It has TPI intake on it, but the driver's side exhaust manifold has the part that you would run a piece of flex hose from to a carb'd engine intake snorkel. That's what puzzles us. The car's VIN has an "F" for the engine code. We know it is a 305, as it has "5.0" stamped on it.

All we know is it is an 87-up motor, as it has centerbolt heads. We were thinking someone blew the original LB9 and had an L03 or LG4 laying around and slapped the TPI intake on that and dropped in the car, but kept the old manifolds on it. It's highly probable as there was a lot of stuff that looked hacked on this car.

What engine we have doesn't really matter, as right now it has blown head gaskets and is sitting in the back of his K5 blazer, awaiting the next tailgating Honda. We're just curious what we pulled out of his car.