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#1 |
Registered User
Join Date: Dec 2013
Location: Wasilla, AK
Posts: 39
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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.
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72 Custom Camper 4x4 04 2500 HD - 8.1/Allison |
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#2 |
Registered User
Join Date: Aug 2010
Location: Edwards, CA
Posts: 7,503
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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
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Thanks, Tim * 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 Highlanders ** Do you have a 1972 Plaid Pickup? ** Plaid Blazer ** Plaid Suburban |
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#3 |
Registered User
Join Date: May 2014
Location: Putnam, CT
Posts: 86
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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.
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#4 |
Registered User
Join Date: Dec 2013
Location: Wasilla, AK
Posts: 39
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Re: 8.1L swap questions
Thanks! This helps a lot. Any idea where to look for the transfer case adapter?
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72 Custom Camper 4x4 04 2500 HD - 8.1/Allison |
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#5 |
Registered User
Join Date: Dec 2013
Location: Wasilla, AK
Posts: 39
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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.
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72 Custom Camper 4x4 04 2500 HD - 8.1/Allison |
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#6 |
Registered User
![]() Join Date: Jan 2012
Location: Humble, Texas
Posts: 414
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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.
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Matt Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=672655 "Father thank you for the gathering of friends, Father we give thanks for all the choices we've made because that's what makes us who we are, let us forever cherish the loved ones we've lost along the way and most of all THANK YOU FOR FAST CARS!" |
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#7 |
Senior Member
![]() Join Date: Nov 2001
Location: Rapid City, SD
Posts: 2,281
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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.
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My Trucks: 1967 Chevrolet Short Wide Box 327 TH350 9" w/3.90 gears paint will be White - Current Project 1967 Chevrolet Custom LWB 283 TH400 3.73 Posi, no-AC, no-PS, no-PB, bench-seat, small-window - mostly orig driver 1967 Chevrolet CST LWB originally a 327 TH400 3.73 Posi AC PS PB, had Buddy Buckets, Small Window - parts truck 1967 Chevrolet CST LWB, 283 MT 3.73 had Buddy Buckets, Panoramic Window - parts truck 2001 Chevrolet 3500 2WD Crew Cab Dually 8.1L Allison White |
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#8 |
Registered User
Join Date: May 2014
Location: Putnam, CT
Posts: 86
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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.
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#9 |
Registered User
Join Date: May 2014
Location: Putnam, CT
Posts: 86
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Re: 8.1L swap questions
I'm new to this, but what is a spid?
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#10 |
The Older Generation
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Location: Montezuma, Iowa
Posts: 25,483
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Re: 8.1L swap questions
That would be the spec sheet on the inside of the glove box door.... LockDoc
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Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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#11 |
Registered User
![]() Join Date: Jan 2007
Location: Central Coast California
Posts: 1,026
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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...
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1972 K20 Suburban 5.7/700r4/NP205 Dana 44/H052 Sold ![]() 1972 C10 5.3L/4L60E 12bolt 5Lug - Sold ![]() 1971 K5 Blazer 6.0L LQ9 4L60E NP205 Dana 44/H052!!! ![]() 1970 K3500 1ton CrewCab 8.1L/Allison1000/NP205 Dana 60/14B!!!! - Sold ![]() ![]() ![]() 1984 K10 SWB 7.4L/4L80e/NP208 Corp 10/12 bolt Sold ![]() 1988 V30 CCLB 7.4L/TH400/NP205/Dana 60/Dana 70/3.73!!! (Sold) ![]() 2003 K2500HD 8.1/Allison1000/NP263 ![]() |
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#12 | |
Registered User
Join Date: Dec 2013
Location: Wasilla, AK
Posts: 39
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Re: 8.1L swap questions
Quote:
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?
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72 Custom Camper 4x4 04 2500 HD - 8.1/Allison |
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#13 |
Registered User
Join Date: Dec 2013
Location: Wasilla, AK
Posts: 39
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Re: 8.1L swap questions
Here be the SPID.
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72 Custom Camper 4x4 04 2500 HD - 8.1/Allison |
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#14 | |
Registered User
Join Date: Dec 2013
Location: Wasilla, AK
Posts: 39
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Re: 8.1L swap questions
Quote:
Thanks.
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72 Custom Camper 4x4 04 2500 HD - 8.1/Allison |
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#15 | |
Registered User
Join Date: Dec 2013
Location: Wasilla, AK
Posts: 39
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Re: 8.1L swap questions
Quote:
I keep hearing that Jim's is excellent at customer service during the installation phase. That's a big plus. Thanks!
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72 Custom Camper 4x4 04 2500 HD - 8.1/Allison |
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#16 |
Registered User
![]() Join Date: Jan 2007
Location: Central Coast California
Posts: 1,026
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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.
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1972 K20 Suburban 5.7/700r4/NP205 Dana 44/H052 Sold ![]() 1972 C10 5.3L/4L60E 12bolt 5Lug - Sold ![]() 1971 K5 Blazer 6.0L LQ9 4L60E NP205 Dana 44/H052!!! ![]() 1970 K3500 1ton CrewCab 8.1L/Allison1000/NP205 Dana 60/14B!!!! - Sold ![]() ![]() ![]() 1984 K10 SWB 7.4L/4L80e/NP208 Corp 10/12 bolt Sold ![]() 1988 V30 CCLB 7.4L/TH400/NP205/Dana 60/Dana 70/3.73!!! (Sold) ![]() 2003 K2500HD 8.1/Allison1000/NP263 ![]() |
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#17 | |
Registered User
Join Date: Dec 2013
Location: Wasilla, AK
Posts: 39
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Re: 8.1L swap questions
Quote:
Thanks. This helps.
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72 Custom Camper 4x4 04 2500 HD - 8.1/Allison |
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Tags |
cross member, ecm, electronic throttle, engine swap 8.1, motor mounts |
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