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Looking for info on the Caddy 500

MudFrog

MudFrog

1/2 ton status
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Decided to retire the 350 next year in favor of a Caddy 500. I need to know what's involved in the swap, I've done some research but any how to's would be appreciated. What I know so far is you need custom motor mounts, more cooling and an adapter for the tranny. What else is needed?

According to the link below it seems as if the 500 from a 1970 would be ideal as it is rated at 400hp and 550 ft-lbs of torque in the stock form. I was a little surprised to see that starting in 1973 they lowered the hp and torque considerably. Caddy Site Any thoughts on these?

Like I said I'm looking to do the research now so I can know what I'm getting myself into.
 
well as far as the horse power drop off i think it is when they swiched from checking it at the flywheel to checking it at the rear wheels
 
www.500cid.com everyhting a young chevy wheeler would ever want in a caddy motor (and then some) /forums/images/graemlins/thinking.gif /forums/images/graemlins/waytogo.gif you'll love the cad motor, stronger, lighter, and definatly more bling factor! /forums/images/graemlins/peace.gif /forums/images/graemlins/peace.gif
 
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well as far as the horse power drop off i think it is when they swiched from checking it at the flywheel to checking it at the rear wheels

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Wow.. it's that dramitc of a drop going through the drivetrain?

So my 210hp rated 350 is that at the rear wheel or flywheel?
 
Also the earlier ones used 72cc heads and 10:1 compression and the later ones used 120cc heads and 8.5:1 or so comression so that had something to do with it
 
I was tempted to put the 76 500 I have in my 79 C10 when the motor blew,but I didnt have the bucks to do it right,so I went with a 305--I'm going to wait awhile,until someone like moroso or mildoon makes a conversion oilpan and pickup tube,and maybe by then I'll have more money to blow on such a project--another reason I didnt do it is I think the Caddy motor belongs in a 3/4 or 1 ton truck where its tourque could be put to better use towing or carrying weight--a 1/2 ton would make a fun hot rod,but not good for much else.
I read the MTS board on the www.500.com website often--a lot of good info on there,from those who have done or are about to do a caddy swap. /forums/images/graemlins/crazy.gif
 
Also a little reading will show a swap of Caddy 425 heads onto a Cad 472 or 500 will bump the compression up to the point where you can only use premium fuel! Its reported a bolt-on 47Hp.

I went that route as I'm on propane with a high 103 octane level. Also if you find the pan out of a FWD Cadd with a 500, it'll have the correct oilpan. You can also use the 425 pan with some "clearancing" with a hammer.
 
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Also a little reading will show a swap of Caddy 425 heads onto a Cad 472 or 500 will bump the compression up to the point where you can only use premium fuel! Its reported a bolt-on 47Hp.

I went that route as I'm on propane with a high 103 octane level. Also if you find the pan out of a FWD Cadd with a 500, it'll have the correct oilpan. You can also use the 425 pan with some "clearancing" with a hammer.

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I read this as well for the compression bump but there is a flow issue that has to be addressed along with this mod. Not as big of a problem when your after the low end torque anyway. Something to consider though.
 
I am also starting this conversion. I have a 500 out of a 70 FWD Eldorado so my oil pan issue isnt there and I have the 10.1 compression motor. There wasd also a difference in the tops of the pistons (part of the reason for the change in compression) Beside moving the engine mounts foward 4 inches and bolting on the adapter ($55 dollars from jegs) It all bolts up.

If you have the money to spend look at a stroker kit. 529, 540 and there is another one. These are supposedly making hp #'s of 650 and torque at about 750. Thats awesome. These motors werent designed to go over 4000 rpm so the valvetrain is the weakest part. This is why I am putting bigger valve double valve springs and upgrading my rockers and pushrods (I want to prerun my truck so 4000+ is a possibility)

On this subject though how do you mate the caddy power steering pump to the chevy gear box? Custom lines or do you bolt the gm pump to the caddy motor?
 
Cool, at the moment I'm not looking for a 650 hp monster although it would be nice. I've found a couple sources with the 1970 version of the motor for about $600 and it runs. I want to do as little as possible to the motor at first (nothing more then gaskets or possibly rings) and then in the future I might look into the stroker kits. What carb to run? A guy in my club swears by the Truck Avenger, he is also the only one that has been able to follow me on steep inclines (due to my tbi). What's ideal for this motor a 750 or so?

I was curious about the steering pump etc.. as well. Any insight on those?
 
I plan on fabbing up some bracketry to the fit the GM pump to the motor. Mine cad didn't come with the pump so I guess that's the main reason for going that route. Adapting lines would probably be the easiest.
 
I will probably just get lines fabbed. Where can you get that done?
 
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well as far as the horse power drop off i think it is when they swiched from checking it at the flywheel to checking it at the rear wheels

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No, thats when they went from gross to SAE net ratings.

SAE Gross ratings are performed on an engine dyno with only items required for it to run on it. Basically fuel/oil/water pumps, and a carb.

SAE Net ratings were also on an engine dyno, but with everything in place on the motor. All engine accessories that would be used in the production car, a full factory exhaust system, all emisions components, ect.

All manufacturers switched to Net in 1972. this is why there is such a massive drop in the power ratings.
 
If your truck is pre-1981,it should have regular SAE flare fittings on the steering box--after that they used metric o-ring fittings--you may find the pressure hose from the caddy might work ok if the box is the old style,if not you can have a custom hose made at any place that makes hydraulic hoses for backhoes and farm equipment,or if you can spend a few minites with an illustrated buyers guide for P/S hoses at a parts store,you can usually come up with one that will go right on. At the store I worked at I had to make a lot of custom hoses,many times I would just cut the hoses from each vehicle in half,and crimp a male and female pipe thread fitting on each end and screw both halves together--I did this mostly when going from an old pump with SAE flare fittings to the newer O-ring style steering box end--the old hoses with SAE flares on both ends were a peice of cake. /forums/images/graemlins/crazy.gif
 
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I will probably just get lines fabbed. Where can you get that done?

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We have a place local that can fab up hydraulic lines. They aren't something that has any kind of DOT approval but they can stand some 2.5 times the pressure that a standard hydraulic steering line can handle. Check with your local auto parts supplier. They can point you in the right direction.
 
I've read that the Cadillac 500 is 100lbs. heavier in stock form than a small block Chev and is supposed to get 1/3 better gas mileage than a big block Chev. The 1970 Cadillac 500 (from an Eldorado I beleive) is the most potent Cadillac 500 made. There is a guy in Alaska that has done the swap (I'll see if I can find his name).
 
It is approximately 50 lbs more than a stock chevy when you put an aluminum intake on it and there are guys doing this swap pulling of 16 - 18 mpg in 3/4 4x4 trucks. But dont expect that kinda gas mielage right away. (b/c the first month or so you will be realizin you have 8.2 litres of gm power in there. BYE BYE GAS MIELAGE AWWWWWWWWWW BBCaddy)
 
The stock caddys came with either a 750 or a 800 quadrajet I believe. Wether or not you need a better or bigger pump depends on what you are already running for a pump.
 
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