'54 GMC big block 4x4 S-10 build

[Steve@OldSub.com]

I've decided to tackle a new project. I'm going to build a '54 GMC 1/2-ton four-wheel-drive on an S-10 4x4 frame with a 454/TH400/NP205.

Now you think I'm crazy. So does my wife so you're in good company.

Today I managed to swap a Dana rear I got free and am sure I'd never use for an S-10 4x4 rear. That was the one significant piece I lacked for this project so now its time to commit and start working on it.

I've had both the '54 GMC cab and the S-10 frame (minus rear) for years. The 454 and other pieces are in a wrecked truck I've been parting out since the accident a little more than two years ago.

I'm going to use GMC stuff for two reasons. First I prefer the GMC grill and dash. Second it gives me more length in the engine compartment which will be important with the big block.

While I'll have enough torque to break axle parts I plan to drive this careful enough that doesn't happen. The front diff will be the 7.2 instead of the 9.25 in the motor donor truck. The rear axle is a 7.5 10-bolt instead of a Dana 70HD like the donor truck. I'll make up for these downgrades by taping an eggshell to the accelerator.

The GMC cab is a 5-window that is in great shape from the belt line up. However the floor, cab corners and driver's side cowl all need replacement. And its got other problems too. I also have a '54 Chevy 3-window cab I'm not going to use on anything else. My plan is to separate the top from the GMC along the seams at the back and in the cowl at the front, taking the 5-window part and the GMC dash and putting it all on the Chevy cab.

I'll probably use the top removed from the Chevy to repair a sunroof in another GMC I have.

I have an extra set of seats from a C4 Corvette I think I'll put in this truck.

Steering column will either come from a 70's Chevy van allowing leaving the ignition switch in the dash or from the '89 truck donating the 454. I need to determine if it will make any significance difference to wiring the TBI motor and will make the decision on that basis.

The wheels will be an old set of slotted mags that I've had for nearly 30 years. The wheels have a nostalgic appeal for me and seem the right choice for an old four-wheel-drive hot rod.

In some ways this is a project of opportunity. I have the major components setting around already. In other ways it is very practical. I see the finished truck as something I can drive on those rare days when it snows around here. It doesn't happen every year, but when it does it can be nasty. But also I live in a very wet area and often need four-wheel-drive to get around parts of my own place. My place isn't as big as that sounds, but moving my trailer to where I store stuff, while only a few hundred feet, can require more driven wheels. Also this truck will be the shortest four-wheel-drive I've owned in decades, and with a new fence my neighbor built I can no longer swing wide enough with my long pickup to back my trailer into my back parking area. This short truck should solve that problem too.

So there aren't really any pictures yet because all I've done is collect pieces so far, but once I start actually doing work I'll change that.

Any thoughts or comments about what I plan to do would be welcome.

[winchster]

Sounds good to me. I'm doing quite the same only I'm doing it with a fullsize blazer ( K5 ) frame instead. The axles and whether or not the s10 frame can live with the bb and the 205 are the only downsides that I see to using the s10 frame. That being said, I will definitely subscribe to a build thread for it.

[BlueJeep]

Originally Posted by winchster

The axles and whether or not the s10 frame can live with the bb and the 205 are the only downsides that I see to using the s10 frame.

The s10 frame will be every bit as good or better than a k5 Blazer frame. It's boxed partway, engineered better, and won't have nearly the frame flex.

As to the TBI wiring, it won't care what you use for a steering column. Also, will you adapt a Ford 205 to get the driver's side drop on the transfer case? I'd probably recommend running a 241 transfer case instead, assuming your '89 donor wasn't the V-series (73-87 style) it should have one.

[winchster]

Originally Posted by BlueJeep

The s10 frame will be every bit as good or better than a k5 Blazer frame. It's boxed partway, engineered better, and won't have nearly the frame flex.

Now I think you may be overstating that just a tad. I honestly don't think the midsize GM platform is capable of handling a big block as well as a full size frame designed for one. The axles won't hold up under a big block. That is documented from one end of the 4x4 community to the other.

[BlueJeep]

Originally Posted by winchster

Now I think you may be overstating that just a tad. I honestly don't think the midsize GM platform is capable of handling a big block as well as a full size frame designed for one. The axles won't hold up under a big block. That is documented from one end of the 4x4 community to the other.

I never said the axles would be better than k5 blazer parts, I only said the frame would be.

OldSub, I agree with you in that if you're not hard on it, it will probably last a long time. If you do start to pop rear shafts, it would be very easy to swap that out for something different. Your donor being a 1 ton may have a borg warner transfer case but it'll work just the same, and have the correct driver's side drop for the s10 front axle. As long as you don't try to go too big on the tire size, I think you'll be just fine.

[Steve@OldSub.com]

Originally Posted by BlueJeep

will you adapt a Ford 205 to get the driver's side drop on the transfer case?

My '89 is a K3500 and is not the earlier body style. It does have a driver's side diff, I confirmed that by looking underneath just the other day.

I realize I'm living on the edge a little bit with this build. I'll have a power plant strong enough to break the diffs and axles. On the other hand 50 is receding in my rear view mirror and its rare I drive the way that breaks parts. My daily is a Corvette and I've never even been pulled over driving it.

I'll keep the 9.25 front differential from the K3500 with the thought that if I break the 7.2 I'll try to adapt the bigger differential and axles. That will create some challenges at the wheel end but I'll figure that out when and if it becomes necessary.

I'm less worried about the rear. If I break the weeny S-10 rear I'll figure out what makes more sense. Maybe a GM 12-bolt or even a Ford 9-inch. I'd prefer not to change from the 5-lug pattern to a 6- or 8-lug so I'll start with the 5-lug that I want and try to stay there.

[winchster]

Originally Posted by Steve@OldSub.com

I realize I'm living on the edge a little bit with this build. I'll have a power plant strong enough to break the diffs and axles. On the other hand 50 is receding in my rear view mirror and its rare I drive the way that breaks parts. My daily is a Corvette and I've never even been pulled over driving it.

So, what you're saying is you're still a young man.

I don't doubt that for your desired result it will work just fine, I was only stating my doubts about the axles mainly. If you do jump on it real hard the rear will probably let go, that being said, if you are careful and use it wisely, it will probably last forever.

[Steve@OldSub.com]

No drag racing, no rock crawling and no heavy towing at speed.

The 454 is more because I have it and am tired of tripping over it plus I'm really tired of seeing small blocks every time a hood goes up. And maybe a little bit of I like my cars to get out of their own way...

[MrTucker]

Originally Posted by Steve@OldSub.com

No drag racing, no rock crawling and no heavy towing at speed.

The 454 is more because I have it and am tired of tripping over it plus I'm really tired of seeing small blocks every time a hood goes up. And maybe a little bit of I like my cars to get out of their own way...

One thing to consider guys is just because it's a 454 doesn't mean it's going to have 500 hp. Stock 454's in the 70's-80's only produced about 275 hp. My grandfather had an 1980-something Chevy with a 454 and the thing was a dog. I've driven 350's that had more power than that thing

[Dan Bowles]

Hear, hear on the Big Block. We are going to put a 402 (started life as a 396) into my younger son's '49 1 ton panel. Should scoot it down the road.

On that thought, you could look at a 12 bolt and keep the 5 lugs. We got a posi out of a 1984 Buick Estate Wagon for his. It is the larger pattern but still 5 lugs. The other thought is an older Camaro/Cutlass/Monte (pre 78) 12 bolt if you can find one. They go for a bit more $$ than a 10 bolt but it'll be 5 on 4 3/4 and be stronger. You'll be running the rear axle much more than the front and if you are looking at towing, you'll have increased pressure already.

But if you've already got what you already have...run what you brung!

[Steve@OldSub.com]

I traded a Dana 70-HD, one of the stronger axles out there, for this wimpy 10-bolt... My goal was something that would easily bolt under the S-10 and which might match the ratio in the front diff and which would turn it into a roller. Sometime I'll have to check the ratios to find out.

Meanwhile run what I brung is exactly where I'm at. And near-term turning it into a roller will make a huge difference to me. Unfortunately I've discovered I don't have any wheels with tires to put on it.

I have a 350 that makes more horsepower than the 454. I'd have to look up the specs to be sure, but I suspect the 454 makes more torque, and its torque that is likely to break things.

I have an 80's Corvette with TPI and while there is no question which you'd choose for a quick trip on dry pavement, the 'vette or a TBI 454 K3500, there is also no question which you'd choose to pull a trailer or move any heavy load.

But I agree, this 454 isn't a 500 horse power house. Driven reasonably I am not likely to break any parts that aren't already defective in some way. On the other hand it would bark 10 inch wide tires pretty much any time I wanted it to when powering a 5,200 pound pickup.

What will it be like in a 3,600 pound hot rod? Fun. And that is the real purpose behind this build.

[Dan Bowles]

I'm with Steve. I've got a 454 in my '92 3500 dually x cab. I can haul small countries all day long at 9-10 mpg or drive it without a load at 12 mpg. AND I've managed to do a 4 tire burnout with it. Now those are some tiger stripes!