3100/3400 crank

[prophiseer]

alright, pretty much doing a stock rebuild with a slightly larger bore for a 3400 in a 1999 Grand Am . . .


my question, though - just realized the crank I have on this '99 spare motor that's being built up is stamped 3100 - is it interchangeable with a '99 3400 motor? GM lists a part number specific for the LA1 . . .

Dimensions and specs are exactly the same, and (IIRC without having a 3400 crank to look at) the only difference I can think of would be the crank trigger . . . I guess, my real question is whether the 3100 trigger would work with a 3400 PCM?

If not, I guess I'll have to dig up a crank for this build

[Superdave]

they are identical.

[prophiseer]

thanks man - that's kinda what I thought, just wanted to clear it up.

The spare motor was a 3400, came out of an Alero IIRC - but that's trying to remember a coupla years ago . . .

I'm fairly certain the '01+ 3400 have their own specific crank that's different from thje '01+ 3100, but wasn't too-too clear on the early 34s

what threw me off was that 3.1 stamp on the crank

Thanks again, though!

[robertisaar]

its kind of like asking is the crank from a 305 and a 350 the same. yes they have identical specs, but the 350 has more counterweight since the pistons on a 350 weigh more.

i don't know if its the same for 3100/3400 but something to think about

[geoffinbc]

All 3.1L/3.4L/3100/3400 cranks have said "3.1L" since the first one was cast. They are the same. I am not 100% sure about the counterweights but since the cranks have the same casting number and same 3.1L stamp I would wager they are the same but a 3.1L may just require more or larger holes drilled in the counterweights for balancing.

[prophiseer]

Like I mentioned, I wasn't entirly sure - I had even called the dealership our shop deals with, and they told me the 3400s were specific to that motor . . . but, that seemed a little odd to me as 99% of all components are interchangeable between the '99 3100 and 3400 motors.

I had figured that if there was a difference, it would be the crank trigger . . .

[bszopi]

Up until the 3500 (and the 3400 in the Equinox) was released, the crank trigger has been the same since it was first introduced in 87 (?).