I have a 97 Monte Carlo Z34. I The old 3.4 has a head leak and is over 215,000 miles. I have a 3800 sc that was just built for another project that has been put on hold. My question is this. Can I install this engine using the origonial trans? I have the wiring harness and computer for the 3800. It came out of a 2001 Grand Prix. Is it rhat simple or am I way off?

 

I believe you will need the 3800 trans, but bumpin or z34phoenix are the guys to ask as they've recently done this swap to their fifth gens

Edit: Also zipper would be good to ask. With the gears on the DOHC it'd be very difficult to launch that car in my opinion. With FWD I think anything above 3.29 is a little too much but that's just me

 

Thank you oneslowmonte While I don't have any experience with the DOHC engines, I can say that 97 Z34's came with the 4T65E (that's a good thing) and the gear ratio should be 3.29:1. The bad thing is that you need a wiring harness from a 98-99 Monte Carlo Z34 or Lumina LTZ (with a 3800), in order to have a good swap. The wiring harness from an 01 Grand Prix will need to be modifyed significantly in order to make that work (in other words, look for a Z34 wiring harness).

Something else to think about is that even though an L67 will bolt up to your tranny, don't expect it to have a lot of life (especially with 215k miles). Some of us have been lucky and are still rocking the original trans with modifyed engines (like myself), and others have lost their trannys with stock NA L36's. You may want to save some money for a built tranny from www.tripleedgeperformance.com

 

Read this thread: https://montecarloforum.com/forum/en...67-swap-14610/

 

You wont be able to control a DOHC trans with a 3800 PCM. The gear ratios are different. You would need to have the PCM tuned to work with your current trans. It would make more sense to find a used HD trans from a supercharged car and swap it in.

 

Well if it is the 4T65E then it shouldn't be a huge issue swapping in a new transmission. 97s always make me a bit nervous though because MOST of the transmissions (Including the N/A transmissions on the 3.1 and 3.8L Grand Prixs and other W-bodies) in 97 was the 4T60E and was vacuum controlled. The ABS is also set up differently in 97 as well IIRC and it makes it a pain in the *** to swap in new transmissions. That's the thing that makes me nervous about any swap dealing with a 97 W-body. Take it for what it's worth, but it's a well known issue on the GP forums.

 

What is the gear ratio in the 97 4T65E trannys? I think I remember reading something about them a long time ago, but I can't remember anymore.

Another thing to think about getting would be a Powertuner or an HPTuner to work out the PCM after the swap.

 

ok. zipper is right your best bet is to get a 5th gen 3800 harness. Z34 LTZ and even the police 9c3. you wont be able to use the 01 harness or pcm. i had to get a 98 pcm as the 99 pcm i had would not accept a 98 file. from stats i have read, the 97 Z34 had 3.43 gears. not sure what they did to get it like that but it had the same ratio as the 96 Z. no mater what you do i wouldnt attempt a swap unless i had a tuner myself. i just wouldnt trust all that work on the swap to rest on someone else finishing the tuning for you and be stuck on their time table. it just gives you more flexibility to be able to tweak the tune yourself. that said. some people have l67's with 3.69 gears! the 3.43 shouldnt be that impossible to launch. but yeah it will deff be a culture shock from your DOHC. im still shocked at times with the L36 na compared to my DOHC with 3.73's! the tq comes in so much lower. and going from 3.73's to 3.29's is a big change too. at least my hw mpg is better again.

it is a lot of work to complete the swap. but i feel it was worth it to me since i want to keep the car a long time.

also if you think you will install headers... now is the time to cut out the fire wall to make room. i can post photos of what i cut and where i should have cut more to make room for the O2. other then the sensor, they fit great and no problems at all. i used speed daddy headers and got them for under 200 shipped on ebay.

 

^^^Most of the L67 transmissions had 2.92 gears stock IIRC. So it stays in the power bad a little longer in each gear. Port that Gen III and you make power even higher up in the RPM band too. Although, if you can get your hands on a Gen V M90 and swap the Gen III MAF onto it it's just as good (if not slightly better) stock than a ported Gen III. Or you can swap the entire L32 top end if you feel like converting to DBW but that's a lot more work than I'd feel like doing and I'm not too fond of the way the pedal feels on DBW cars.

 

the OP said he had a 01 L67 on hand so swapping to a gen V or l32 isnt a viable option. the 2.92 gears help with mpg. which is better for each application is really up to the owner. if your making a track car 3.29's or higher would deff get you better times. if your doing lots of highway driving the 2.92's will be better. i dont do very much highway and perfer to use the 3.29's to get into a higher gear faster and ride the tq of the motor.

To Mike D... when you say your DOHC has a head leak what do you mean? those engines are bullet proof. mine died at 224,000 because the timing chain inside stretched... as the timing belt was still fine. i prob could have retimed it and been good, but my trany wasnt doing well and it was cheeper to swap to the 3800 with a trany then retime it and replace a trany.