81 k10 305 to 454 motor swap

[krisclark92]

Hey guys I have a 1981 k10 with a 305 in it, I destroyed my tranny and possibly a head gasket. A boss of mine at work has a 454 paired with a beefed up 350 tranny. My worries here are what ill have to do get it to work, any help will be appreciated. He is giving me the fan and radiator. I have a speed demon jr. Carb to put on top of it when im ready. The 454 has two burnt valves cause the original owner tried to run a msd ignition on it so ill get it resurfaced.

[b454rat]

Pull 305, drop in 454. Not 100% on tranny, been long time since I did my swap...P/S might need some fab'n but nothing hard.

[krisclark92]

Originally Posted by b454rat

Pull 305, drop in 454. Not 100% on tranny, been long time since I did my swap...P/S might need some fab'n but nothing hard.

Thanks, ill post pictures when it stops raining and snowing, will I need to do any mount work for the motor or should it match up pretty well?

[krisclark92]

Wil the frame be able to hold up to a 454?

[INSIDIOUS '86]

Originally Posted by krisclark92

Wil the frame be able to hold up to a 454?

How could it not? If a fiberglass corvette can hold a bbc down fine then a truck won't sweat it.

Move fine two bbc swaps on 305 trucks. If the trans is already bolted on just pull the front end off and slider her in. The radiator and hoses are the biggest diff. And the throttle cables are diffrent off sbc and bbc but both work.
Exhaust is diffrent between the two but if you already have dual exhaust then it shouldn't be to hard to fix it to bbc headers

It's pretty straight forward swap.

[krisclark92]

Originally Posted by INSIDIOUS '86

How could it not? If a fiberglass corvette can hold a bbc down fine then a truck won't sweat it.

Move fine two bbc swaps on 305 trucks. If the trans is already bolted on just pull the front end off and slider her in. The radiator and hoses are the biggest diff. And the throttle cables are diffrent off sbc and bbc but both work.
Exhaust is diffrent between the two but if you already have dual exhaust then it shouldn't be to hard to fix it to bbc headers

It's pretty straight forward swap.

I had a buddy tell me that its possible i could crack the frame with the power of it over time. Will I need to relocate the motor mounts? Will my driveshafts have to be shortened? Im going to shorten the exhaust to behind the doors what diameter exhaust would you recommend? Sorry for the questions this is my first swap let alone first bigger motor swap

[INSIDIOUS '86]

Originally Posted by krisclark92

I had a buddy tell me that its possible i could crack the frame with the power of it over time. Will I need to relocate the motor mounts? Will my driveshafts have to be shortened? Im going to shorten the exhaust to behind the doors what diameter exhaust would you recommend? Sorry for the questions this is my first swap let alone first bigger motor swap

Considering 85% of bbc's aren't making more than 350hp and are s****** motors I highly doubt it. If people can pull two wheels off the ground for multiple seasons at the track without issue then I wouldn't worry. The frames typically crack by the steering box and the shock mounts.

Your driveshaft stays the same. As for diameter of exhaust a 2.5in system handles everything just fine

[Zoomad75]

SBC to BBC is a direct swap to the existing motor mounts and trans. You'll need the BBC accessory drive for the brackets to the p/s pump and alternator (a/c compressor too if yours works). These trucks had the BBC as an option from the factory so they can handle them just fine.

[krisclark92]

Sweet, thanks guys for helping me out on this, I sure do appreciate it.

[BigBlocksRule]

GM put the mounts on all engines the same with regards to the tranny location. That's why a 4.3 sits so far back and a 454 fills up the engine bay to the front.

[krisclark92]

Originally Posted by BigBlocksRule

GM put the mounts on all engines the same with regards to the tranny location. That's why a 4.3 sits so far back and a 454 fills up the engine bay to the front.

I have predrilled engine mount holes on the frame so thats a plus for me, ill have the same model tranny put in just beefed up, im getting a working 454 with a 350 turbo tranny for 1500 I just have to pull it. The motor has only 12000 miles on it so im stoked about that. Will it be a belt driven fan or better to go electronic as regards to the fan?

[BigBlocksRule]

I'd do a little research into using an early 90's truck serpentine system on your big block. Ease and convenience of serpentine setup that looks decent.
I've always been an engine-driven fan guy, one with a clutch that works right will be just fine. Just don't forget to get the correct shroud and install it!

[krisclark92]

Originally Posted by BigBlocksRule

I'd do a little research into using an early 90's truck serpentine system on your big block. Ease and convenience of serpentine setup that looks decent.
I've always been an engine-driven fan guy, one with a clutch that works right will be just fine. Just don't forget to get the correct shroud and install it!

Will do, thank you good sir

[nekkidhillbilly]

454 was an option your buddy is a dummy.

[krisclark92]

Originally Posted by nekkidhillbilly

454 was an option your buddy is a dummy.

I though the 454 was only available for the k30 so did he

[nekkidhillbilly]

no gm had some 70s trucks that had them in c10s. iirc too c20s had the 454 option not a 100% on that.

[krisclark92]

Originally Posted by nekkidhillbilly

no gm had some 70s trucks that had them in c10s. iirc too c20s had the 454 option not a 100% on that.

Ok,cool

[dwntwn]

Motor mounts for small block and big are different—the frame mounts are the same, though.

Originally Posted by Zoomad75

SBC to BBC is a direct swap to the existing motor mounts and trans.

[krisclark92]

Originally Posted by dwntwn

Motor mounts for small block and big are different—the frame mounts are the same, though.

Im planning on putting new mounts on regardless it was the location that was concerning me

[dwntwn]

You'll be good then. I just did the same thing you're doing with an '80 C10 a few weeks back. It was a originally a 250 inline six, 4 speed transmission, I put in a 402 big block (same dimensionally as 454) with a TCI street fighter automatic transmission (th350)

I had to swap a few more things that you might have to—I went to a 1 piece driveshaft (originally the truck was a 2piece)

After that I had to put a different crossmember in for the automatic, swappped to an automatic steering column, I even switched the brake pedal (but its still a high-hump floor, so I don't know who I think I'm kidding)

Going v8 to v8 will be less work than what I did for this one. Even the wiring here and there wasn't much of a big deal—but the truck's wiring was pretty intact from the start.

[krisclark92]

Originally Posted by dwntwn

You'll be good then. I just did the same thing you're doing with an '80 C10 a few weeks back. It was a originally a 250 inline six, 4 speed transmission, I put in a 402 big block (same dimensionally as 454) with a TCI street fighter automatic transmission (th350)

I had to swap a few more things that you might have to—I went to a 1 piece driveshaft (originally the truck was a 2piece)

After that I had to put a different crossmember in for the automatic, swappped to an automatic steering column, I even switched the brake pedal (but its still a high-hump floor, so I don't know who I think I'm kidding)

Going v8 to v8 will be less work than what I did for this one. Even the wiring here and there wasn't much of a big deal—but the truck's wiring was pretty intact from the start.

I just talked to the guy that im buying it from and he said its not a 350 tranny but a heavier duty tranny not sure of the number on it, the motor and tranny are being pulled from a model A rv camper. He said the emergency brake is on a drum not sure what he meant by that.

[krisclark92]

I guess my new question is will the transmission with drum brake system installed on it still work for my truck without any modifications to the driveshaft

[dwntwn]

The parking brake assembly is most likely added on because it was an RV application. I've seen this setup on older cars, but don't know much about what it would take to remove it.

Either way, I'm guessing the transmission he's talking about is a Turbo Hydramatic 400 (TH 400, or some people call them Turbo 400s) Basically a 3 speed automatic but used in heavier duty applications (3/4 ton, 4wd, big block, etc) than a TH350.

Your truck is 4wd, right? Its a different transmission than 2wd, so unless this RV is 4WD, it won't work for you.

Also, this motor you're buying has 2 burnt valves, and the heads will have to come off just to get it running, right? I hope you're getting a really smoking deal, because it might end up being more of a headache than you want to get into.

Here's an option you might want to consider— pull your transmission and get it rebuilt, then look for a running 350ci motor. I don't know the specifics, what you have to spend, what kind of deal you're friend is hooking you with for the 454, but really, unless its next to FREE, you might be in for a lot of unforeseen nickel and dime expenses, or some really HUGE ones.

Originally Posted by krisclark92

I guess my new question is will the transmission with drum brake system installed on it still work for my truck without any modifications to the driveshaft

[krisclark92]

Originally Posted by dwntwn

The parking brake assembly is most likely added on because it was an RV application. I've seen this setup on older cars, but don't know much about what it would take to remove it.

Either way, I'm guessing the transmission he's talking about is a Turbo Hydramatic 400 (TH 400, or some people call them Turbo 400s) Basically a 3 speed automatic but used in heavier duty applications (3/4 ton, 4wd, big block, etc) than a TH350.

Your truck is 4wd, right? Its a different transmission than 2wd, so unless this RV is 4WD, it won't work for you.

Also, this motor you're buying has 2 burnt valves, and the heads will have to come off just to get it running, right? I hope you're getting a really smoking deal, because it might end up being more of a headache than you want to get into.

Here's an option you might want to consider— pull your transmission and get it rebuilt, then look for a running 350ci motor. I don't know the specifics, what you have to spend, what kind of deal you're friend is hooking you with for the 454, but really, unless its next to FREE, you might be in for a lot of unforeseen nickel and dime expenses, or some really HUGE ones.

Im getting the motor and tranny for 1500 and I pull it

[nekkidhillbilly]

more than valves are getting burnt.