How can I externally id an engine?

[scrappy]

I have a '00 LIM and I have a 3400 UIM how can I tell what the engine is? I was told that it was a 3100 and it was removed because it had piston slap. The dealer bought a complete engine to replace it. It was in Anchorage AK and the emissions laws won't let you swap a larger displacement engine in (can't put a 3400 in place of a 3100 and drive it in Anchorage). can I identify it by a block #? what are the identifying caracteristics?

[bszopi]

Look on the side of the block (either tranny side or timing cover side, can't remember) and it will have either a 3.1L or a 3.4L cast into it. That will tell you if its a 3100 or a 3400.

[patgizz]

even if its a 3400 - they shouldnt know the difference if you put a 3100 plenum on? i doubt they would go searching for #'s on a stock looking engine.

[scrappy]

even if its a 3400 - they shouldnt know the difference if you put a 3100 plenum on? i doubt they would go searching for #'s on a stock looking engine.

They look at the block # and verify it is the correct displacement for the car/ year. I had a buddy with a '79 3/4 T Chevy, it originally had a 350 in it and still did BUT the new engine was a LD emissions engine and it came with a HD emissions engine so they would NOT pass it for emissions. Externally they were identical looking.

[scrappy]

Look on the side of the block (either tranny side or timing cover side, can't remember) and it will have either a 3.1L or a 3.4L cast into it. That will tell you if its a 3100 or a 3400.

is this on the front side or rear side? with the engine in the car.

[bszopi]

Well, that won't work, since its under the timing cover...

On the tranny side of the engine, most likely on the firewall side, look for a letter A or B cast into the block (near the head). A will be 3100 and B will be 3400.

[scrappy]

It's a 3400!

Well, that won't work, since its under the timing cover...

On the tranny side of the engine, most likely on the firewall side, look for a letter A or B cast into the block (near the head). A will be 3100 and B will be 3400.

Thanks for the help, I found the B on the engine painted red. I would be happy if it was a 3100 but I still would have probably have put a 3400 in it later, now I got what I wanted and didn't even realize I already had it!

One inconsistancy though, Another site said that the 3400 timing cover has a boss to install another idler pulley and the cover that was installed on the engine when I got it does not. the cover was still bolted on and they had no reason to take it off so I am pretty sure that it belongs to the engine. does the front cover differ from car to car?

[bszopi]

Yes, the front covers will vary depending on the application.

[TazMan]

Ok guys, I know I'm resurrecting an 11 year old thread here, but I happened to be searching the forum, trying to find out how to tell a 3400 from a 3100. Upon reading this post, I realized that the 3100 I have sitting in my garage, which I pulled from my Lumina, has a B stamped on it. I'm also pretty sure that when I swapped in the 3400, I looked to make sure the stamp wasn't the same letter B, and the engine I swapped in had an A stamped on it. Is it possible that you guys have it reversed and the 3100 is the B, and the 3400 is the A, or did I somehow manage to swap in a motor that was really weak, for a downgrade? The original motor was a dog and it is much more powerful since the swap. Only upgrades are ported intake manifolds and a 65mm TB and plenum opening

[1QUICKHATCH]

3100 is a B
3400 is a A
3500 is a C (non vvt Lx9)

[TazMan]

PHEW!!! LOL