I'm thinking of building a motor for my 2003 Monte Carlo ls ....it's got a 3400 in it, I've heard you can put heads off a 3100 and increase the compression, and then put the top end (uim, lim) off a 3500 for more air+fuel flow has anyone tried this before? Also thinking of putting a mild cam in for fun

 

I don't believe too many people do much for mods with the 3400 in the Montes, as there is a larger aftermarket modding community for the 3800.
But don't get me wrong, there are mods for the 3400 (typically the N-Body/Grand Am guys do more with the 3400).

Here's some good cheap starter mods:
https://montecarloforum.com/forum/fw...p-power-46071/

Also, your question about the top swap.... Typically top swaps have done like this:
3100 gets a top swap from a 3400
3400 gets a top swap from a 3500

The reason is the next generation of the engine had bigger air passages all the way around and made for a pretty straight forward upgrade followed by some computer tuning.

3100-3400 top swap I believe is more straight forward as the design/layout of everything is near identical. Using 3500 parts, GM changed the coil (and with that the coil mounting, so you need to adapt your existing coils to fit) and the throttle body is no longer a linkage, it's drive by wire. But these obstacles have been over come before.

Remember, it all comes down to how much are you willing to pay to play. And with a 3400, be careful how much you spend, as you may be money ahead swapping to a 3800.

Hope this helps and gives some food for thought.

 

There was a turbo kit for the 3400 for sale in the parts for sale section here a little bit ago. Buy that and that will be more than enough power for you I'm willing to bet.

 

I'm just currious, my cousin was big into the 3400s but he never did anything more than basic bolt on mods....my motor is starting to knock and I'm thinking of a mild build on it, no power ladders tho (sc or turbo) I don't want to worry about room, I'd also like to find a way to make it a manual too....I have found out like you said, pay to play 3400 parts aren't cheap...I have no clue how much I want to spend yet

 

i think some fiero's were manuals with a 3400, could maybe take their tranny but you would probably need their drivetrain as well since they are rwd. And myself do have a 3400 but honestly i don't think you need to build them. would rather l67 swap it

 

Fiero's pre-dated the current 3400 LA1 engine. They may have been a 3.4, but not sure if they truly had the same foot print.
The N-Body guys can swap a Cavvy Getrag F23 manual trans to the 3400 and I believe some have used a G6 trans (there is a write up out there that makes it sound almost like a weekend project). But the Grand Am's benefit from the 4-cylinder model of the car had a manual trans option (so junk yard parts are available for pedal clusters, trim pieces, cables and linkages) to swap over. The Monte and other W-body cars never had a manual trans option. I know of two different 3800 owners (Impala and Grand Prix) that did all the custom fab to put a manual trans into their cars.

Now, this knocking on the engine, if it's a true knock, that's NOT good. Is this sound upper or lower engine? I know the 3100 and 3400 engine tend to give a little valve tick (especially as they get older). But if it's a knock, you may have bigger problems coming up.

I suppose the very first thing is finding what kind of budget you have and marry that up with how deep a project is it worth. If you are going for bigger performance and have a larger budget, knowing you could put a 3800 L36 or even better, L67 right into the car, I think that might be the better way to go.
Otherwise, based off the cheap mod list, might thoughts would be:
- Put on some L67 coils
- Either a CAI or gut the air box (either way, more free flow of air coming in)
- Get the SS dual exhaust and the resonator removed from the exhaust, and if you can, also the U-Bend removed.
- Finish with a decent mail order tune

All that would net some reasonable added performance and should not cost anything crazy to do (especially if you can do most the work yourself and source some good salvage parts).

My '04 Grand Am is running:
- K&N air filter on the stock Ram Air box
- L67 Coils
- When I bought it (with about 100K on it) did basic maintenance (plugs, wires, trans fluid/filter changes).
- Minor computer tuning.
I've also done a couple visual and suspension mods (they don't apply to a w-body conversation). But just what I listed, some small but noticeable improvements improvements.

 

Exactly what i have done to my car minus the tune but that's soon. It sounds pretty good and i agree with everything else he said. Best of luck to your build though

 

The knock is bottom end...it's gonna need a new motor soon, it's not too loud but loud enough for me to start thinking of replacing, I've been a mechanic for years so I know the work needed, never built a motor tho, I've done exhaust on the car already, got duals off the down pipe coming out behind the rear door, no cia, never really believed in it, and not really a good idea for all the gravel roads I go on...I've never heard of coil swap on it tho?

 

The L67 coils have been known to burn the spark plus hotter for better throttle response, some people believe it and some don't. I think it did help a lil bit but it's not like a huge difference

 

I run L67 coils (when looking at factory coils the plug on the underside of L67 coils are blue). It's a mod worth about $15-$40 (all my coils have been used coils, never a problem, they last a ridiculous long time).
I've ran them on a 3100, 3400 and 3800. You don't notice them as much when you put them on, but when I demodded the 3100 and put the stock ones back on, I was not as happy driving it, lost a little "something".
The end result swapping the coils is not worth dropping big money on a set of coils, but I feel if you want a little more out of the car, it's a reasonable mod (hence why I have them on mine). And the factory ICM is 100% fine to use.


Some do and some don't believe in the CAI. It's also a car-by-car situation. Some cars from the factory have a great air intake and others have room for improvement. Odds are on a 3400, since the air box is the same as a 3800 and a 3800 uses a wider throated throttle body, the air box is probably fine for a 3400.
But, I don't think you loose anything by a CAI or gutting the air box. I know you mentioned you are traveling a lot on dirt/gravel roads, honestly I don't think that matters. You still run with an air filter, you just have more of the filter exposed for getting air into the car. And there are a few selections on the market of clean-able/re-usable air filters (like a K&N).
Just food for thought.