L29 (Vortec 454) in Square?

[TravisMartin]

I'm toying with the idea of putting an L29/4L80E in my '78. I've searched but haven't found where anyone has done it; has it been done and documented? I'd sure like to see what it looks like in the bay. The biggest concern I see so far is routing the air intake plumbing around the air conditioner suitcase. If anyone can shed any light I'd sure like to hear it and even better see some pictures. If it turns out I'm blazing a new trail I'll try to post some pictures in case someone else wants to try it.

[DirtyLarry]

L29’s are great engines! If you have an opportunity to grab one, go for it! I ran an L29 for a short time about 5 years ago. Actually, it was a 454HO crate engine with a marine L29 powder coated intake, C/K truck L29 accessory brackets, and RamJet 502 harness and MEFI-4 ECM. After months of trying to fine tune the ECM I got frustrated with it and yanked the whole thing then installed a L18 8.1L. The L18 has a lot more power than an L29 but the L29 is much cleaner looking engine without the exposed coil packs and wiring.

Really, to do an L29 7.4L swap isn’t much different than doing an L18 8.1L. Use a Howell Engine Development harness or something similar and have the ECM tweaked and use a TBI fuel tank with a TBI sending unit along with an EP381 fuel pump. You can make the stock L29 air intake system work or use something like Spectre tubes and unions to build your own.

The marine L29 intake. Same intake as the truck L29 except powder coated and the RamJet 502 is a speed density system that does not require a MAF.




Replaced the L29 concoction with an L18 back in 2008

[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

[mtnsackett]

Larry, what are you running as your rear gear set up and what are you averaging for fuel mileage?

thanks

[DirtyLarry]

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

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.

Originally Posted by mtnsackett

Larry, what are you running as your rear gear set up and what are you averaging for fuel mileage?

thanks

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.

[TravisMartin]

Mine is going to be a weekend toy 2WD, so I think I'll go with electric fans. I've about come full circle and decided to use the L19 (TBI 454) I already have instead of an L29. I really like the L29; had one in a 99 Suburban. But the TBI will look almost factory and, like I said, I already have it...I bought a rough '95 C2500 that runs superbly and uses no oil, no leaks, stays cool, everything you could ask in a streeter. Should be a great donor for my '78 shorty. It was an original 454 truck, but the engine had been replaced with a small block when the friend I got it from bought it...he'd had it since 1986. Doubt there's any chance of finding the original.

My brother & I retrofitted a 91 TBI 350 & 700R4 in his 84 (he bought it new) last summer and I was pleased with the way it turned out. We even put the electronic speedo cluster out of the 91 suburban in it. On the 84, the hole for the harness to the ECM is already in the firewall; it was used for the electronic spark control on the original 305. I'll have to cut the corresponding hole in my '78, as I'm figuring to mount the ECM over the glove box as on the late TBI squarebodies.

I like the way your truck looks. Thanks for the help.

[DirtyLarry]

Yeah, electric fans would be perfect for that. An L19 would be nice too and like you say, it will look more factory. Even better that you have one on hand! L19’s have great low end torque but peter out pretty quickly at 3,000 RPM’s on up. They make for a better 4x4 engine than sport truck engine.

Remember the 454HO/L29 morphadite above? After it got replaced by an L18, it sat on an engine stand from 2008 until last January where I bolted it in to my father-in-laws GMT400 C1500. I sold the marine L29 intake/harness/MEFI-4 ECM then put a carbureted intake on it with a Howell TBI adapter and used a 1992 7.4L TBI unit. It is like an L19 but with L29 accessory brackets. It runs alright but a modern 5.3L would put the beat down on it from stop light to spot light. These TBI engines just don't have any top end power. Here is a thread on the 4.3L to 7.4L swap.

[86454k30]

Originally Posted by DirtyLarry

Yeah, electric fans would be perfect for that. An L19 would be nice too and like you say, it will look more factory. Even better that you have one on hand! L19’s have great low end torque but peter out pretty quickly at 3,000 RPM’s on up. They make for a better 4x4 engine than sport truck engine.

Remember the 454HO/L29 morphadite above? After it got replaced by an L18, it sat on an engine stand from 2008 until last January where I bolted it in to my father-in-laws GMT400 C1500. I sold the marine L29 intake/harness/MEFI-4 ECM then put a carbureted intake on it with a Howell TBI adapter and used a 1992 7.4L TBI unit. It is like an L19 but with L29 accessory brackets. It runs alright but a modern 5.3L would put the beat down on it from stop light to spot light. These TBI engines just don't have any top end power. Here is a thread on the 4.3L to 7.4L swap.

Little thread revival here but........Larry what A/C lines did you use when you had the L29 in your truck?

[DirtyLarry]

Originally Posted by 86454k30

Little thread revival here but........Larry what A/C lines did you use when you had the L29 in your truck?

The A/C line in the picture above is an off the shelf Napa L29 A/C line from like a 1998 K2500 7.4L spec. When I had this engine in my ’78 K10 the A/C line was a custom made hose from the local Napa store

[manimal]

more good info...
http://www.nastyz28.com/forum/showthread.php?t=7811

[chris989]

Originally Posted by DirtyLarry

L29’s are great engines! If you have an opportunity to grab one, go for it! I ran an L29 for a short time about 5 years ago. Actually, it was a 454HO crate engine with a marine L29 powder coated intake, C/K truck L29 accessory brackets, and RamJet 502 harness and MEFI-4 ECM. After months of trying to fine tune the ECM I got frustrated with it and yanked the whole thing then installed a L18 8.1L. The L18 has a lot more power than an L29 but the L29 is much cleaner looking engine without the exposed coil packs and wiring.

Really, to do an L29 7.4L swap isn’t much different than doing an L18 8.1L. Use a Howell Engine Development harness or something similar and have the ECM tweaked and use a TBI fuel tank with a TBI sending unit along with an EP381 fuel pump. You can make the stock L29 air intake system work or use something like Spectre tubes and unions to build your own.

The marine L29 intake. Same intake as the truck L29 except powder coated and the RamJet 502 is a speed density system that does not require a MAF.




Replaced the L29 concoction with an L18 back in 2008

I know this is an old thread but may i ask another question?

Did you try to use the factory air filter set up from the vortec? did it just not fit or clear the AC evap.

Thanks,
Chris

[DirtyLarry]

Originally Posted by chris989

I know this is an old thread but may i ask another question?

Did you try to use the factory air filter set up from the vortec? did it just not fit or clear the AC evap.

Thanks,
Chris

Nope, didn't even bother to try a factory L29 air intake....no need as this engine ran on MEFI-4 ECM that does not require a MAF sensor