Thread: 454 swap help

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Howdy, I’m new here but I once heard forums are the place to go for things like this and I’m all out of options. Recently I picked up a new project, more so my first project, and of course being me I have to go all out (because who wants to take things slow). I’m trying to swap a 454 big block into a 91 C1500 single cab which came stock with a v6 and a 5 speed manual. I have a clue as to what i need to do, but at the same time this is all new for me and I could use like a checklist or something or even just things to take into account. Literally any advice will help!

New motor mounts, probably a bigger radiator, different transmission and mount and probably different gears in the rear end to name a few.

Welcome to CHR!

Here's a thread that is very similar to what you're wanting to do:
1993 C1500 project: 4.3L to 7.4L swap > 454SS clone - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Lots of good ideas and this guy has already researeched all the bits and pieces.

Good Luck,
Glenn

Is a new ECU required for this kind of swap? The mechanical parts I have a good understanding of but I’m not sure if I can just plug and play the harness with the old ECU.

Yes, the fuel setting on a v6 will not feed a 454. There is going to be almost zero that you can use from The v6 and transmission that will work with a big block.

Is there an aftermarket ECU y’all recommend or is my best bet pulling one from a 3500 with the same specs?

In my opinion, if you can find a 3500 that matches up to what you want to do?!?! Get it or as many of the parts you can from it.

Originally Posted by TXAG22

I’m trying to swap a 454 big block into a 91 C1500 single cab which came stock with a v6 and a 5 speed manual.

As pointed out on another thread about smog laws, you should first check to see legalities.

Thanks for the help y’all this is all new to me! As for smog laws I’m in Texas and out here I’ve seen boosted LSAs in a 70s f100 just rollin so I think I’ll be okay.

Originally Posted by TXAG22

Thanks for the help y’all this is all new to me! As for smog laws I’m in Texas and out here I’ve seen boosted LSAs in a 70s f100 just rollin so I think I’ll be okay.

Be careful, a 1970 vehicle comes under different smog laws (both State and Federal) than a 1991 does. Check before you leap...

You might want to take a look at this, opening the fact sheet link towards the bottom - https://www.epa.gov/enforcement/engi...ing-fact-sheet

Alrighty it’s been a while since I started this! Coronavirus definitely slows everything down. I got to get some work in the truck today and have a harness question, it runs from the ECU to everything in the truck correct? Wondering because I found a 91 5.3 and I’m trying to part it out (a 454 just isn’t in the college kid budget lol)