8.1L swap questions
 

I am preparing to swap an 8.1L engine and 4L85e transmission into a 1972 3/4T 4WD Custom Camper truck (picture below). I have seen some info on this forum that helps a lot, but still have several questions.

1 what are the pros and cons of using the electronic throttle vs an older mechanical throttle body. I have all the parts needed to do either.

2. What motor mounts are best to use?

3. Who should I use to reprogram the ECM? I see members of this forum talk about Jim's Performance and Howell. I can't figure out which is best. Any opinions and recommendations would be welcome.

4. Did you have to change the front cross member to clear the 8.1 oil pan? Where did you get the cross member?

5. What about cooling? I have the radiator out of the donor vehicle ( 2003 suburban). Do I need it. The 72 has a pretty healthy radiator already.

6. The truck has a factory in-dash tach that works great. Can I make it work with the new engine?

7. What exhaust manifolds work best?

I am sure there will be many more questions as I work through this build. Any help and ideas would be appreciated.

Re: 8.1L swap questions
 

Best place to start is with the search button, there are a number of threads and a few builds as I recall.


Here is a thread of DirtyLarry's I'd bookmarked with a lot of great 8.1 info.
http://67-72chevytrucks.com/vboard/s...d.php?t=298696

If you would, how about posting up your SPID?

* VIN/Model Decoders
* Power Team Charts (engine/transmission/gear ratio)
* Post Your Pickup SPID Blazer SPID Suburban/Panel SPID
* RTFM ... Read The Factory Manuals... download 'em here

Re: 8.1L swap questions
 

I used howell engineering. I have the fly by wire set up that works great. you can use 73-87engine mounts to install engine. with that engine and trans you will need new drive shafts, transfer case adapter, remote oil cooler, and standalone harness. Stock manifolds will require trimming the frame to fit, shorty headers will work best. you may also need to move engine forward as transmission is longer than original. This swap is a lot of work but is nice when complete.

Re: 8.1L swap questions
 

Thanks! This helps a lot. Any idea where to look for the transfer case adapter?

Re: 8.1L swap questions
 

"If you would, how about posting up your SPID?"

What's a SPID?

You're right, Larry's info will be invaluable. Thanks.

Re: 8.1L swap questions
 

I used 150tunes.com for my pcm flashing and wiring harness changes. I sent them the entire harness and the pcm, they took off what I didn't need for my application and built an OBDII port into the harness.

Re: 8.1L swap questions
 

My boss used Jims Performance on a 2wd 8.1L/Allison set-up a few years ago. He was very happy with his products and his helpful service after the sale on unrelated issues.

Re: 8.1L swap questions
 

I used advanced adapters, you will need a two wheel drive output shaft on trans and some machining on transfer case. Sound scary but was real easy.

Re: 8.1L swap questions
 

I'm new to this, but what is a spid?

Re: 8.1L swap questions
 

That would be the spec sheet on the inside of the glove box door....

LockDoc

Re: 8.1L swap questions
 

I used an aftermarket engine cross member and the stock pan. The stock front 72 crossmember doesn't have to be changed. I think stock '72 bbc mounts and cross members should work. Use 72 stock bbc stock manifolds. Like Dirty said, it should be a simple bolt in mount up.

I used the stock 8.1 harness and computer. I flashed it with hptuners. Seemed to work fine but I sold it before i drove it. It did drive up the trailer and had no c.e.l. come on for the many months I had it running.

You should be able to use the stock radiator. I used an electric fan. And, I think you should be able to use the stock tach if you run a jumper/resistor to a switched 12v source...

Re: 8.1L swap questions
 

I hope to use the 72 raditor and an electric fan as well. Glad to hear of your success. The motor mounts and exhaust manifolds shouldn't be too hard to find. All good info - Thanks!

I am a little confused. You used an after market front crossmember but are saying that the stock one will fit under the 8.1 oil pan, right?

Re: 8.1L swap questions
 

Here be the SPID.

Re: 8.1L swap questions
 

Based on some new info that I recently got from the Pirate 4x4 forum (great forum, BTW), I am thinking of using an NP241 passenger side drop transfer case from Midwest Transmission Center. It has the 32 spline input that I need and should bolt right up to the 4L85e tranny. Anyway, that's the plan now.

Thanks.

Re: 8.1L swap questions
 

My son is looking for that same 67 cst short wide box that is your next project. Have you found one yet?

I keep hearing that Jim's is excellent at customer service during the installation phase. That's a big plus. Thanks!

Re: 8.1L swap questions
 

Lets be clear, there is the front crossmember and the engine crossmember.

The front crossmember stays put. The stock bbc engine crossmember can probably stay put… I used an aftermarket because I didn't have one. I think Dirty Larry used an aftermarket out of preference…I think it was an ORD high clearance one.

Re: 8.1L swap questions
 

Sounds like I need to spend a little more time underneath the truck! I'll get it figured out.
Thanks. This helps.