The Stovebolt Site Forums The Shop Area The HiPo Shop caddy 500 into a 54 3100

I'm working to put a mid 70's caddy 500 motor into my 54 3100.
Looking for anyone who might have done this to see what problems they ran into and solutions they used.
Curious as to firewall modifications, front of engine to radiator clearence, (I would like to try and use the stock fan), and whether there was a need to relocate the master cylinder.

Mine is on a S10 frame, but I had no firewall problems.
W/your stock frame you should be able to use the stock Caddy fan.
Also on my project I was able to keep the pedal under the floor and even added a power brake booster to it. The only problem you may run into is if you want dual exhaust w/the brakes being under the truck, there's a clearance problem. But you could reroute the duals to one side then split them back up in the rear..Joe

I'm working on a similar swap too.

I'm putting either a '75 or a '76 Cad 500 with TH 400 into a '54 or '55 1st GMC 1-ton. If you are using a rear drive motor you need to know it has a front sump pan, and you'll need either a rear sump Eldorado pan or a mid sump pan from a later 425.

There are some differences between your Chevy 3100 and my GMC 250, but most of the issues will be the same.

I did not see a way to clear the toe board and keep the bell housing crossmember in place. My decision was to remove that crossmember allowing mounting the motor lower and a little further back.

That does make the interference between the exhaust manifolds and the frame a little too tight. I've not solved the problem yet, and may end up trimming a quarter inch off the inner edige of the frame rails.

There is no way to retain the stock steering.

On my GMC I see the oil filter interfering with the engine crossmember. Choices here are a remote filter or cut that crossmember out of the way. I suspect you will have the same problem.

Those are my initial thoughts. I'm also converting to IFS on the front of mine, in part because I removed the crossmember between the spring mounts, and in part because I wanted to get modern brakes.

I see no need to relocate the master cylinder but would suggest adding that much power you really want to augment your brakes too!

Today mine is stripped to the frame with the IFS install underway. I don't expect to finish that for some time, and won't remount the cab or test fit the motor again for months. But I want to hear how your project is going and will be happy to answer any questions about my project that you can ask.

I cant help you with the insatallation,but the 500 Caddy is a very good engine. I picked up a 1965 Chevy shortbed with a 500 Caddy,and Turbo 400 tranny in a trade.It is one great running truck,its a real pleasure to drive. It wont run with the big block Chevies in the 1/4 mile,as it is more of a cruising engine.

If you can find a copy of Doc Frohmanders Big Inch Caddy book it gives you a list of mounts and exhausrt manifolds that can make that engine work in just about anything. He documents some swaps into trucks in that book. Amazon has it listed at http://www.amazon.com/Big-Inch-Cadi...mp;s=books&qid=1255219756&sr=8-2

Thanks for the feedback. The truck I have already has a front clip from a 97 c10 already mounted. I picked up a universal swap kit from MTS so I need to see how that fits. I have a th400 I'm going to use.
I'll keep updating as I go.
Brian

I pulled apart the front clip to get access to the frame rails. The previous owner had welded on small block engine mounts directly to the cradle. I test fitted the engine and trans and looked at locating the motor mount bosses on the engine directly to the small block mounts using some 1/4 inch plate, but that raises a couple concerns. First of all, no rubber may make the truck vibrate too much, and second, I think the engine is too low in the frame and it may be too far forward because I would like to use the stock fan.
If I raise the engine and push it back I may need to modify the firewall and floorplan. That wouldn't be a showstoper.

The small block mounts in the stock location would be too far back. The Caddy mounts forward, so you may need to look at how the PO put it together and maybe make some changes.

Oldsub, thats what I was thinking but after some trial and error fitting I think I'm going to push the engine back into the firewall, so they're not that bad. I have the engine in place but the back of the heads are resting against the firewall and I still need another inch at least for the fan clearence with the radiator. I found a company that sells a replacement firewall with a 4" recess in it so that's an option. First I will do some trimming myself first and see what happens.Part of the fun of putting it together.

Did they not offer a 454 in a 97? I can't remember but if they did then I'd think the caddy would be a fairly straight forward install with just the normal tweaks encountered. I'd check to see if big block parts may have given positioning that allowed fan, exhaust, etc., clearences. I don't know but it might be worth a check. Here is a picture of a 500 Cad in a 51 GMC that the firewall is stock. http://s32.photobucket.com/albums/d41/coilover/ Scroll down to bottom of first page. It's been over 30 years but I think I used a Ford flathead six cylinder radiator that was mounted forward in the core support. Cooled great. Stay in contact with Oldsub because his views are from right now, not thirty years ago.

coilover, thanks for the info. I have to replace the floor of the cab anyway, I picked up a 5X4 piece of 1/4 diamondplate I'm going to weld in for the floor, so notching it back for the clearence will just be part of the assembly.
I could go ahead and cut out the small block mounts. That would make the location more flexible, but I think I'll leave them for now.

Wow.

Oldsub, is that a good wow or a bad wow

The factory floor material is 18 guage steel if I remember right. Its more like 1/16 thick.

You're going to have a very stout floor that will also add a lot of weight. The truck will carry that weight between every stop at the gas pump, but aside from some cool factor I don't think you're gaining anything.

18 gauge is 0.048, 16 gauge is 0.060

1/4" diamond plate is way too thick and heavy unless your building a tank or a bulldozer (then again the floor of a bulldozer is only 12 gauge (0.105")

besides being difficult to handle to work into place, your welding 18 gauge to 1/4" which means that your welds will crack in a very short time.

good points, I'll have to think about this.