What exactly do I need for a 3100 to a 3400 swap and a 3100 to a 3.4 DOHC swap. I cannot find any straight answers online anywhere and I was hoping someone could help. My 3100 is blown so I figure if I have to do a swap it might as well be an upgrade.

 

Don't do a 3.4 DOHC swap. Those engines are a pain to work on and have almost no aftermarket. If anything, do a 3400 or 3800 swap.

A 3400 swap is pretty much just taking out the 3100 and put in the 3400. Just about nothing else is needed. If the 3400 came out of something other then a w-body, you may have to swap a couple brackets from your 3100, but it's no big deal.

A 3800 swap is a bit more. You should swap the tranny as well if you go this route. Plus you'll need a wiring harness and PCM from a 98-99 Monte Carlo Z34 or 98-99 Lumina LTZ (a 3800 LTZ).

 

I've heard plenty of 3.4 horror stories but I'm stubborn and the couple 3.4's I found are only 300 the same as the 3100. They want 500 out of the 3400's though. I would really like to do the l67 swap lots of info on that one but unfortunately I don't have enough cash for that one.

 

No one can help out with what I need for the 3.4 DOHC? or if it is a direct swap.

 

As an afterthought I believe I have the 4t65-e trans so what else would I need for the 3.8

 

PCM and the Wire harness from a 98-99 Monte Carlo Z34 or Lumina LTZ (with 3800)

 

Thanks, did all 97-99 montes have the 4t65 or did they still put the 60's in the 3.1's?

 

I'm not 100% when they made the switch

 

Well I imagine I can crawl under and look. Would you be able to tell from the oil pan?

 

4T60E's came in all 1995-1999 Monte Carlo LS' and 4T65E's were in all 1997-1999 Monte Carlo Z34's. I would seriously discourage you from doing the 3.4L DOHC like I already mentioned. To swap in a 3.4L DOHC you would have to do the same things that you would do for a 3800 swap (wiring harness, PCM, mounts, etc).

Let's break the engines pros and cons down a bit.

3.4L DOHC pros:
Higher peak hp
Good mid to high end performance
Unique engine

3.4L DOHC cons:
Almost no aftermarket
The engine hasn't been produced since 1997
Difficult engine to service

3800 v6 pros:
Good low to mid range torque
Easy engine to service
Almost infinite aftermarket

3800 cons:
Minor common issues (LIM gasket, UIM warps)
Very common engine
Hasn't been produced since 2007 (2008 model year)

If you want a super easy swap that will give you 20hp 20lbs ft, then do a 3400 swap. Otherwise, go with a 3800. Another plus about the 3800 is that it gets MUCH better gas mileage then the 3.4L DOHC.