Quote:
Originally Posted by TravisMartin
Thanks, that's a lot of what I was looking for, especially the second picture...I needed to determine how much of a clearance issue I was going to have with the a/c suitcase. From that picture, it doesn't look like a big deal at all. I'd like to pipe in air from the grille to the air cleaner; looks like there's room to maybe make that work.
I'm an old fart and a bit of an originalist; don't want to build a hotrod as much as the truck I think GM might have built if the technology had been available in 1978 and the feds had been minding their own business. My thinking is a stock L29 with a 4L80E, using the PCM & mounts just like in a GMT400. I don't know why I can't use the GMT400 harness as well, modified to interface with the '78. If the air inlet is going to fit, the only hurdle I see now is the speedometer, and I don't see that as much of an issue...I can get a mechanical tail extension or an electronic speedo.
I was already under way to do this with an L19/4L80E, but the L29 is beckoning...
Your installation looks superb. Are you running a mechanical fan? I was tentatively planning to go with electrics. Otherwise, I think maybe you've already paved the way.
I appreciate the quick response. Do you have any more pictures of the L29 setup posted anywhere?
Travis
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That is exactly the theme behind my swaps…make them look like they would have if the technology had been there in 1978. I would not recommend using a complete donor harness from the truck the engine comes from. Think about it, the last L29 as built in 2000. That is already 13 years ago, and those harnesses are stiff and all the weather pack connectors are brittle. Don’t mess with them. The best $500-$700 you can spend on any EFI engine swap is to start with a clean new harness that you don’t have to piece mail together/rip circuits apart. Most guys that have problems with LS swaps, etc. are using old molested donor truck harnesses. Don’t be that guy. If you start with a new harness, you have 4 connection to either tie into the original harness or run fresh (hot all the time, key on, fuel pump and Tach).
Speedo could be a challenge with an electronic transmission into an old ’78 cable driven cluster. Maybe an electric 1990-1991 square body style Blazer, Suburban, or crew cab cluster could be the donor cure for that problem. Probably cheaper to find an electric speedo cluster than swap a mechanical output on the back of a 4L80E.
Yes, I run a mechanical fan clutch. My truck was built for long distance off-road adventures in mind where I run a medium duty truck clutch fan. It is loud and robs power but the truck never gets hot wheeling around the desert of Arizona or Utah even on 120 degree days crawling along at 4 MPH. Never a worry that he electric fan, relay or any of that stuff will fail. The medium duty fan clutch moves A LOT of air at low RPM. The mechanical fan is simple and durable. If I were building a 2WD street truck or stay close to home 4x4, I too would be looking at an electric fan though just to spare a few ponies.
No sir, those are the best L29 pictures I got.
Plenty of L18 8.1L swap pictures here. The meat and potatoes of an L29 and L18 swap are pretty much the same outside of air induction plumbing.
Quote:
Originally Posted by mtnsackett
Larry, what are you running as your rear gear set up and what are you averaging for fuel mileage?
thanks
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4:56 gears, 35” tires with .73 OD trans.
Just returned home for a 2,435 mile overlanding trip to the Mojave Desert, Death Valley, Canyonlands of Utah and back home a few weeks ago. While I didn’t keep as close track of gallons used as previous trips, it feels like we came in pretty close to last years trip which came in at 11.72 MPG. Not too bad for an 8,000 lb. 4x4 with the aerodynamics of a drive-in-movie theater screen. My stock 2001 Silverado HD with an 8.1L does about 12-13 MPG but with no camper or load.