What motor is best for a swap on a K25

[1978k25]

Hey y’all, I’m not sure what type of motor to put in my 1978 K25. I want to upgrade as the current motor does have a lot of issues. Any help will be greatly appreciated. Thanks

 

[SquareRoot]

That's an easy one. Just don't ask what kind of oil to put in it.

 

[Big red square]

454 bbc IMO

 

[HotWheelsBurban]

Hey y’all, I’m not sure what type of motor to put in my 1978 K25. I want to upgrade as the current motor does have a lot of issues. Any help will be greatly appreciated. Thanks

350 or 400 small block. Lots of torque in the lower RPM ranges where you need it for a 4x4. Factory offered the 400 in them for that reason....

 

[MarineOne]

Depends on budget and what your doing with it

 

[Drauka99]

350 SBC (or 383 stroker) or 454 big block if you want to go old school with carb

5.3 or 6.0 LS for a fuel injected flavor.

none are bad choices, just depends on what you like and how much work you want to do.

 

[TotalyHucked]

That's completely subjective, we can't make that decision for you. You need to decide what kind of motor is right for you. Do you like carburetors or fuel injection? Do you like small blocks, big blocks or LS motors? What's the truck used for? Do you have an overdrive trans? What's your budget?

When I bought my truck, I specifically planned on LS swapping it with an overdrive trans because I knew I wanted to roadtrip it long distances. I'm most familiar with the LS architecture, they're super easy to make power with and get great fuel mileage to boot.

If I were buying a budget C or K20 to use around town, I wouldn't bother LS swapping. I'd stick with a carb on a small or big block and just build a healthy version of whatever's in it. That would be the cheapest/quickest way to do it.

 

[CountKrunk]

Bode vision on YT is doing/ has done a 70s or 80s gmc 3/4 ton dump truck. Check that out, he's simply rebuilding what needs rebuilt on the drivetrain it came with. He explains why. Like others have said, you need to figure out what you want the truck to do and go from there.

Example, i have a sbc 350 with a 3 speed auto. Will likely get a beefed up 70r4 so i can go 70mph (55-60 with the ears pinned back now lol). Everything on it works, so id rather keep the original flavor engine and slip in a trans thats more suited to modern highway speeds.

 

[Shorty81]

I'm with @Big red square , BBC. I stroked and bored my 454 to a 496. Very happy mill.

 

[75gmck25]

Your first step is to determine a rough idea of your budget and time schedule, and then review your mechanical skills and tools. 2nd step is to describe how you plan to use the truck (daily drive, load hauler, off-road fun, etc.). Then post the answers here and you will get better input.

 

[Buck69]

Gearing and tire size would play a big influence if it were my decision.

 

[idahovette]

My wallet ALWAYS is the greatest influencer in my decisions

 

[GTX63]

Welcome to GMSB. I hope you aren't a one and done but your questions begs questions so come on back. Upgrade how? A used 305 that runs and doesn't smoke or leak oil is an upgrade over a used 305 that smokes and leaks oil.
What specifically do you want and in what order?
Durability? Dependability? Performance? Modern convenience? Gas mileage?

 

[Big red square]

I'm with @Big red square , BBC. I stroked and bored my 454 to a 496. Very happy mill.

How much power you think your making roughly?

 

[Shorty81]

How much power you think your making roughly?

Not sure. The shop that did the machine work guessed approx 500 hp. I don't think it's that high, but it sure is a low rpm torque monster!