454 tbi with 4l85E swap into c1500 350tbi

[Needs15]

Not sure about the 94 rad but I have a 91 3500hd rad and its way to big for a 1500 too tall, front is the 1500 back is a 3500hd. Doing the same exact swap on my truck as well. Just a 91 454 and 4l80e into a 92 1500

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[alpinecrick]

Hell, just drop in the 454 and then add shackles on the back - instant 2/4 drop!

That's the spirit.......!

 

[alpinecrick]

Not sure about the 94 rad but I have a 91 3500hd rad and its way to big for a 1500 too tall, front is the 1500 back is a 3500hd. Doing the same exact swap on my truck as well. Just a 91 454 and 4l80e into a 92 1500

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That's why the 3500HD's had the filler--way big radiator. A regular 3500 radiator fits in the standard spot as the 1500's and 2500's.

 

[Bloodwater79]

If it's a real 3500HD as stutaeng is asking you, those are 15K GVWR trucks and the 4L80E has an extended tailshaft housing with a drum parking brake at the end of it. Not really the best swap candidate for putting into a C1500..

Most people refer to regular 3500's (and 8 lug 2500's) as HD because GM tended to as well, though that's not the actual model name. So, assuming your 454/4L80E came from a regular 3500, just bring everything over. Engine, trans, engine wiring harness, PCM, radiator/shroud, and fuel pump. Yes, fuel pump. 94 and 95 454's have a higher pressure pump (26-32 psi spec) but it will fit your existing sending unit. Or save yourself some future trouble and just buy a new pump spec'd for the 94 454.

And yes on the hydroboost. Much better braking power than the vacuum booster.

No on the serpentine drive bracketry. Small block and big block are not the same.

Richard

Yeah its a true HD, it was a cab chassis with the diamond plate road service truck bed. I pulled the accessory air compressor pump off and the compressor tank but the rear of the truck is pretty rotten, especially for only 64k original miles. the Trans has the e brake on the tail shaft. I was able to get the drum off and unbolted looks like I just need a different slip yoke to have the new driveshaft made up. As long as she has been sitting with an empty tank, he parked it since the tank had a hole in it and it wouldn't hold more than 8 gallons of fuel before it would leak out every where, I was planing on a new fuelpump.
Should I be on the look out for a 14 bolt for the rear of the c1500, or will the 8.5 10 bolt hold for a little while as long as I don't abuse it?
I'll start pulling the hydroboost, doesn't look that complicated, and pulling the rest of the harness and PCM. I have the radiator engine trans and oil cooler out and in one piece. manifolds came off with no issue, hardest part was the Air compressor pump...that thing weight a ton, the bracket was 1/2" plate.

 

[Bloodwater79]

Stiffer coil springs? C1500 didn't have torsion bars, right?

Actually, did any C1500 come with BBC (except SS, of course) from the factory?I believe there were some C1500 with diesel option? Maybe look into those for parts swapping?

I had a 94 k1500 diesel, it had bars, but will have to get under the C1500 to verify if it has them. was planing on front springs

 

[someotherguy]

I had a 94 k1500 diesel, it had bars, but will have to get under the C1500 to verify if it has them. was planing on front springs

That's the difference between C and K GMT400's; C1500 is coil spring, K1500 is torsion bar.

Yes, the 8.5" will hold up - IF you don't abuse it! But what's the fun in that? You should probably start hunting a 9.5" SF.

And yeah; that actual HD radiator isn't going to fit, nor will the shroud, etc. so you'll want at least the wide core radiator from any of the 1500-2500-3500 models and the accompanying shroud. Some 1500's came with the big radiator already, depending on model. If you're buying new then just go ahead and get the 3500 / 454 spec radiator for your year model.

I can't recall but I'm pretty sure pulling the tailshaft from that 4L80E requires full disassembly. I wish I knew for sure, but I bet someone on here does know. Hell if you can fit it as-is under your C1500 I say do that and just have your driveshaft shortened, it's a no-go though if you have a 1 piece shaft as the bolt-on front yoke design of that transmission depends on the slip joint being at the carrier bearing.

Richard

 

[someotherguy]

FWIW, my little dream truck would be a RCSB C1500 with an 8.1/4L80E swap, and of course a 14 bolt out back, maybe leave it 6 lug and swap the front rotors to the C2500LD's so I don't have to go through that re-drill crap again on the rear axles like I did on my '94 C2500LD project years ago.

I'd leave the driveline stock otherwise, just for simplicity's sake, but I'd get a custom tune for the 8.1 to wake it up.

Yeah, you can build lots of power with an LS swap, but everyone is doing LS's, and you lose the "factory style" serviceability with all that custom harness mess. A 2001-2002 3500HD would be the perfect engine/pcm/harness donor candidate for this swap (and I'd source a 4L80E from a regular 2500/3500 to avoid the tailshaft issue), since it would be a GMT400-style harness and all other related parts, it just means I'd be limiting my project truck to a 96-up, the bummer about that being I prefer the 88-94's a lot.

Richard

 

[PlayingWithTBI]

Sounds like a fun project! Yeah, I'd keep it with older controls/PCM to get away from the more expensive programming/tuning although, then you're stuck with speed density, oh well!

 

[Supercharged111]

That's the difference between C and K GMT400's; C1500 is coil spring, K1500 is torsion bar.

Yes, the 8.5" will hold up - IF you don't abuse it! But what's the fun in that? You should probably start hunting a 9.5" SF.

And yeah; that actual HD radiator isn't going to fit, nor will the shroud, etc. so you'll want at least the wide core radiator from any of the 1500-2500-3500 models and the accompanying shroud. Some 1500's came with the big radiator already, depending on model. If you're buying new then just go ahead and get the 3500 / 454 spec radiator for your year model.

I can't recall but I'm pretty sure pulling the tailshaft from that 4L80E requires full disassembly. I wish I knew for sure, but I bet someone on here does know. Hell if you can fit it as-is under your C1500 I say do that and just have your driveshaft shortened, it's a no-go though if you have a 1 piece shaft as the bolt-on front yoke design of that transmission depends on the slip joint being at the carrier bearing.

Richard

Having changed a 2wd 4L80 over to a 4wd, yes it's the 2nd to last component I removed when disassembling the trans. I think the only other thing was a bushing that it slid out of.

 

[df2x4]

FWIW, my little dream truck would be a RCSB C1500 with an 8.1/4L80E swap, and of course a 14 bolt out back, maybe leave it 6 lug and swap the front rotors to the C2500LD's so I don't have to go through that re-drill crap again on the rear axles like I did on my '94 C2500LD project years ago.

I'd leave the driveline stock otherwise, just for simplicity's sake, but I'd get a custom tune for the 8.1 to wake it up.

Yeah, you can build lots of power with an LS swap, but everyone is doing LS's, and you lose the "factory style" serviceability with all that custom harness mess. A 2001-2002 3500HD would be the perfect engine/pcm/harness donor candidate for this swap (and I'd source a 4L80E from a regular 2500/3500 to avoid the tailshaft issue), since it would be a GMT400-style harness and all other related parts, it just means I'd be limiting my project truck to a 96-up, the bummer about that being I prefer the 88-94's a lot.

Richard

All these years on this forum reading about these trucks and for some reason this never clicked with me... I may have to reconsider the engine swap in my red truck. Do the 3500HDs use the same black box PCMs as the standard GMT400s?