3800/L67 swap questions

[Quaraxkad]

I've been thinking about doing an L67 swap for a while now, I'm finally ready to start finding some parts. I've researched and found a few DIYs and FAQs on the subject and it seems relatively straight-forward but most of the guides are not particularly detailed or in-depth. So I still have a couple of questions I haven't yet found answers to...

 

1. The DIYs I've seen are either written specifically for the Monte Carlo or generic "most W-body's". I'm not at all familiar with GM vehicles (yet!), are there any differences between my '92 Cutlass and other W-body's that would differ from what's in that DIY?

 

2. I think it was in a Monte Carlo DIY that I read that the "preferred" donor vehicles are 97-04 Regal and 98-03 Grand Prix. Are these preferred only when swapping into a Monte Carlo or does the same apply to my LH0 '92 Cutlass? And why are these preferred? I'd like to know what the differences are between the potential donors because I'll be searching my local self-service junkyards for an engine and trans, and I will likely need to use multiple donor vehicles to get everything I need so I'd like to know why I should or shouldn't keep an eye out for certain cars. (ie. if the only differences are a couple of engine mounts I can easily source those from one of the "preferred" donors and get the rest from any other)

 

3. Most guides mention cutting and re-welding a section of the firewall for the exhaust. Is there an exhaust from any other car (or aftermarket) that will fit in a Cutlass without requiring this? Or is a custom pipe the only option?

 

4. I know I need an L67 ECU/PCM. Is it the whole ECU I need or just a chip? Is there a preferred year or model I should get one from? I have a chip burner and I'm familiar with chipping and modifying the ECU on my other car, but that car is an entirely different beast in this regard.

 

5. Are there any build threads around that follow this swap done in a similar year Cutlass? I've seen a couple of completed swaps in a Cutlass but I haven't seen a thread documenting anyones progress while doing it. I'd like to make sure there are no "snags" I need to be aware of when doing this swap with my particular year/model.

 

I suppose that's all for now, thanks!

[White93z34]

Ideally, you'll want a engine and transmission from a 97-02 SC w-body. 2003 will work but BE SURE you get the PCM with it or else the transmission will hate itself and never work right. other carlines (bonneville, park ave etc) will work but you'll spend a lot of time hunting down the w-body specific brackets, easier to just buy one with the right parts to begin with.

 

engine harness from a 98/99 L36 monte carlo/lumina it is made for the car and will give or take work just fine. you WILL want to verify both pinouts on the c100 connector to make sure it mates up, and then modify the engine harness as necessary to make it work. will likely have to add a class 2 data bus wire to your existing harness so you can have a diagnostic port under the dash like you do now.

 

exhaust should work if you get a 98/99 lumina/MC L36 downpipe, if you want to run headers thats when you get into headaches of nothing fitting right.

[Quaraxkad]

Ideally, you'll want a engine and transmission from a 97-02 SC w-body. 2003 will work but BE SURE you get the PCM with it or else the transmission will hate itself and never work right. other carlines (bonneville, park ave etc) will work but you'll spend a lot of time hunting down the w-body specific brackets, easier to just buy one with the right parts to begin with.

 

Is it just the brackets I need to be concerned about though? I'll be scavenging my local junkyard for these parts and I can't be too picky. If I did end up with an L67 from, for example, a Bonneville, will any L36 W-body have the right brackets or would I still need to find an L67 Regal/Grand Prix anyway?

[topless94style2]

I'm using probably the same monte guide as you, plus i have technician service manuals for both my 98 regal and 94 cutlass, plus experience as i've removed and installed the LQ1 once already.

 

I will be installing headers too, however my LQ1 has a custom dual set up from a local shop, I will probably take the car there to finish the header install.

 

The more parts/engine/trans you get from a new Wbody, the easier it will be. There's a good chance you could get a wrecked 98/99 L67 vehicle complete for the same price you'll spend collecting all the parts over time.

 

I've read the axels are putting too much pressure on the Diff on lowered cars with the l67 swap and may require custom axels to be built. The easiest way is to combine the inner axel from the L67 vehicle with the outter axel from the Cutlass and install.

 

You'll need the entire ECU. The easiest to work with is the Lumina as mentioned White93z34, but I'll be working with my Regal harness since thats what I have. HP tuners sells software that you can use to tune and program the motor to your liking.

[95 vert]

Bonneville lower bracket/mount is different. L67 only ignition module/coil bracket (not the same as L36-has idler pulley for S/C belt) is different-no dogbone mount holes for w-body. No left front bracket for dog bone mount-though it can be added. A/C bracket is different. Belt length will be different. Bonneville alternator bracket is different depending on year (larger alt.).

So much easier to use a L67 from a GP or regal.

[Quaraxkad]

I'm using probably the same monte guide as you, plus i have technician service manuals for both my 98 regal and 94 cutlass, plus experience as i've removed and installed the LQ1 once already.

 

I have my '92 Cutlass service manual already, and once I find a donor car I will certainly be buying the matching manual for that as well. I don't like to do any work without the proper manuals, you never know when there's a special instruction somewhere!

 

You'll need the entire ECU. The easiest to work with is the Lumina as mentioned White93z34, but I'll be working with my Regal harness since thats what I have. HP tuners sells software that you can use to tune and program the motor to your liking.

 

I'm familiar with tuning software and reading/burning chips, but OBDII is new to me. Are you saying an L67 Lumina ECU is preferred over the ECU from the donor car? Regardless of what ECU I get, which chip would be the best "starting point" to begin tuning with?

 

Bonneville lower bracket/mount is different. L67 only ignition module/coil bracket (not the same as L36-has idler pulley for S/C belt) is different-no dogbone mount holes for w-body. No left front bracket for dog bone mount-though it can be added. A/C bracket is different. Belt length will be different. Bonneville alternator bracket is different depending on year (larger alt.).

So much easier to use a L67 from a GP or regal.

 

Thank you for clarifying the differences. That definitely does sound like too many small parts to bother with, I will certainly be on the lookout for a w-body donor!

Edited May 2, 2012 by Quaraxkad

[topless94style2]

The ECU should be for an L67 doesn't have to be Lumina specific.

 

The wire harness itself is recommended to be from a Lumina as its easier to work with.

 

Since I have a donor car with everything I need, I'm not going to go out looking for a Lumina harness.

 

You won't need a chip for OBD2, the ECU will be flashed with the software. If you want a starting place, a few of the performance parts suppliers for the L67 offer flashed ECUs for much cheaper and they can tune to your mods. ZZP, Intense etc.

 

OR

 

 

http://www.hptuners.com/forum/showthread.php?t=4742

Edited May 2, 2012 by topless94style2

[rich17]

The ECU should be for an L67 doesn't have to be Lumina specific.

 

The wire harness itself is recommended to be from a Lumina as its easier to work with.

 

Since I have a donor car with everything I need, I'm not going to go out looking for a Lumina harness.

 

You won't need a chip for OBD2, the ECU will be flashed with the software. If you want a starting place, a few of the performance parts suppliers for the L67 offer flashed ECUs for much cheaper and they can tune to your mods. ZZP, Intense etc.

 

OR

 

 

http://www.hptuners.com/forum/showthread.php?t=4742

Find a Lumina harness. I know you have the 2nd gen one but trust me. The lumina/monte harness is alot easier to install and alot less of a headache.

[topless94style2]

Find a Lumina harness. I know you have the 2nd gen one but trust me. The lumina/monte harness is alot easier to install and alot less of a headache.

 

Being that I am doing the swap, I should know the difference. But i've yet to find an answer other than it's a lot easier to use. What are the differences to prompt the purchase? Don't get me wrong, I want to this work so if using the Regal harness will be far more difficult than finding a Lumina Harness, I'm on board. I just personally didn't consider a reason other than "its easier" to get me to purchase it, maybe that is the cheapskate in me talking:lol:

[xtremerevolution]

Being that I am doing the swap, I should know the difference. But i've yet to find an answer other than it's a lot easier to use. What are the differences to prompt the purchase? Don't get me wrong, I want to this work so if using the Regal harness will be far more difficult than finding a Lumina Harness, I'm on board. I just personally didn't consider a reason other than "its easier" to get me to purchase it, maybe that is the cheapskate in me talking:lol:

 

Wait till you reach that point in your swap. Then you'll find out why every single person who has done this swap recommends it.

[topless94style2]

I know they recommend it, except no one goes into detail past that its easier.

 

I just haven't found anyone that can say spending $300-400 on this harness will allow me to do something that I can't do with what I have. If someone knows where I can get that detail that would be great as I am having a hard time finding it through the hours I've researched . Otherwise, my wiring diagrams and case of beer will hold me over.

[AL]

I can get a wiring harness for about 50 bucks or so, i don't see why you need to spend hundreds of dollars on something that's extremely common in junkyards

[topless94style2]

I can get a wiring harness for about 50 bucks or so, i don't see why you need to spend hundreds of dollars on something that's extremely common in junkyards

 

 

motorswap.org pushes them out for hundreds, if JY's sell em for 50 then that guy is making a killing. I have no reason to look yet, but if they are $50 then that will come in handy if i ever need one.

[xtremerevolution]

motorswap.org pushes them out for hundreds, if JY's sell em for 50 then that guy is making a killing. I have no reason to look yet, but if they are $50 then that will come in handy if i ever need one.

 

Keep in mind that if he sells them, he has to get new ones from somewhere.

 

I'll bet Bob (BXX) will gladly pull a harness from a junkyard and re-pin it for you for a fair price.

[95 vert]

The 98-9 Monte/Lumina harness looks identical to the Cutlass harness. Keeps your PCM and battery in factory locations. Fits most of the retainers your 3.4 harness used and routes pretty much the same. Only requires some minor re-pinning at the C100 firewall connector and adding a wire to route thru to the diagnostic connector for OBDII. (And replacing the 12 pin for a 16 pin connector)

[rich17]

The 2nd gen does not use a C100. So you have to wire that whole thing in. That and the Battery, Fuse box, amd pcm are all in different spots. It leaves a mess as well to try and mount the harness over the radiators like 2nd gens. Briang's L67 swapped 91 looks like crap IMO

[topless94style2]

Finally some answers the question, thank you both. I spent another hour researching yesterday and the closest thing I found was maintaining stock battery location. If your moving to trunk, obviously doesn't apply. In any case, I put in a request for a used one to check pricing. For $50, yeah, i'd save the labor time too. For a couple hundred, I'll give the rewire a shot. The work doesn't bother me.

 

I'm about half way reading this waiting for the write up on the wiring to show up:

 

http://www.w-body.com/showthread.php/46682-Project-95-GSX/page13

[xtremerevolution]

Finally some answers the question, thank you both. I spent another hour researching yesterday and the closest thing I found was maintaining stock battery location. If your moving to trunk, obviously doesn't apply. In any case, I put in a request for a used one to check pricing. For $50, yeah, i'd save the labor time too. For a couple hundred, I'll give the rewire a shot. The work doesn't bother me.

 

I'm about half way reading this waiting for the write up on the wiring to show up:

 

http://www.w-body.com/showthread.php/46682-Project-95-GSX/page13

 

Wait till you get to the part where Bob had to fit the headers in.

[White93z34]

motorswap.org pushes them out for hundreds, if JY's sell em for 50 then that guy is making a killing. I have no reason to look yet, but if they are $50 then that will come in handy if i ever need one.

 

Just find a junkyard one, if you are not afraid of some minor modifications to it it is super easy to setup for what you need.

[topless94style2]

I found a better reason why the monte harness should be used. Because the regal harness and pcm talk a different language than what the cutlass will understand. Have not found a 50 dollar harness but have found them in the range of 2-4 hundred shipped.

[95 vert]

If you can't find one reasonable, I should be able to get you one that would be in the 100 +\- shipped range.

My local pick and pull has them occasionally.

Best reason for using the 98-9 Monte harness is ease of installation. Really doesn't matter on the "language" thing.

Although IIRC, the car will not start with the Regal PCM without modification (security) but will start with the Monte PCM.

[topless94style2]

If you can't find one reasonable, I should be able to get you one that would be in the 100 +\- shipped range.

My local pick and pull has them occasionally.

Best reason for using the 98-9 Monte harness is ease of installation. Really doesn't matter on the "language" thing.

Although IIRC, the car will not start with the Regal PCM without modification (security) but will start with the Monte PCM.

 

^ better way of putting it. I have a couple calls out but i mayge in touch with you if they fall through.

[95 vert]

Sounds good. let me know:)

[z34Phoenix]

i know some of this has been said but i will reinforce it.

 

I just finished my swap from my 96 DOHC to a L36. i got a 98 z34 harness from the local yard for about $60. i got the engine and trany from Morad that pulled it from a 98 Z34. i think it was two wires i changed at the C100 plug. I also ran a wire from the pcm to connector so later if i wanted i could connect performance shift.

 

specific things i needed were:

-98/99 Z axles

-98/99 Z throttle cable as the DOHC one would not go WOT

-fuel lines and had to mate them to the factory hard line.

-power steering lines

-trany lines

-upper and lower engine mounts for the 3800. the trany mount on the 4t60 still works though.

-my ac lines hooked up fine

-diff heater core lines

 

 

I will be topswapping so i installed headers. I have the SD headers and i cut a 8" x 5" section out of the fire wall. in that area there is a double wall and after i cut it i pounded it out and widened it more. so its not like there is a hole in the floor. the photos i used as ref were for installing pacesetter headers... these need more clearance on the passenger side of the fire wall. my SD headers needed more room on the driver side. as a result of following install for the others my headers rub a little. this will be corrected when i go to install the topswap as when the heads and the headers come off for the install it will give me room to pound at it. if i were just to stay NA the stock manifolds and down pipe from the 98/99 Z would have fit with no problems.

[rich17]

What teo pins did you change in the PCM? Mine was plug and play....?