I performed a couple searches and turned up only people planning the swap; anyone actually finished putting in a Cadillac 425/472/500 into a thirdgen? The big details like motor mounts, transmission, exhaust are not beyond my abilities--I just want to know if there were any wierd hangups like notching framerails for accessory clearance or stuff like that.

 

Anything is possible but it's not going to be an simple drop in like a BBC.

The exhaust is easy. Buy BBC headers for a third gen. Buy the mounting flanges for a Caddy. Cut off the mounting flange on the BBC headers and weld on the Caddy flange. Poof. Instant Caddy headers. I have no idea how they would fit though since I don't know the external dimensions of the Caddy engine.

 

the exhaust is tricky but doable. The headers have to turn really tight, right off of the head. I ran true duals all the way back.The caddy sits in the frame fairly easy, but you have to make plates that stick forward off the cross member. The eldo rear sump oil pan will stick out 2 inches under your crossmember. I shortened it and widened it. And you will need a hood scoop........ Its worth it though. Theres now even aluminum heads available for the big block caddy.

 

I have a couple questions:

Do you have any pictures?

I noticed the motor mounts are farther in front of the motor, how thick are the plates you used?

What trans did you use?

What rearend?

Could stock exhaust manifolds fit?

Which Caddy motor did you use, and is it built, stock, stock-style rebuild, etc?

How much taller is it (i.e. how big of a cowl does it need)?

Do you have any timeslips/how fast is it/what would you say it compares to?

I have a '76 500 thats a stock type rebuild except for a slightly hotter cam from MTS and a rocker shaft conversion that I was going to put into a '77-92 Fleetwood (you know, the 'down sized big body') but the idea of all that torque pushing around 600-700 pounds less is pretty attractive.

 

Search Google For Maximum Torque Specialties, they have everything Caddy!

 

Alright, I used 1/2 inch thick plates that protruded about 4 inches from the frame, and of course drilled holes to the frame and one for the rear wheel drive cadillac mount. You would probably want to dummy the engine together without the internals to reduce weight and test fit the engine in their. Its tight but it will fit. You can easily use stock manifolds, but for over 400 horsepower, dont think about it. If you are set on using them, and I dont blame you because the mock up of the headers are hell with this setup, All I had to do when I checked it out was use the rear wheel drive manifolds, not the eldorado ones. I had to grind the donut flange a little on the passenger side. I am running true duals right now. You can run single exhaust, but you have to modify the 425 mid-rear sump pan......For the transmission, use the TH400. I had mine built with kevlar bands and raybestos friction plates....It will be fine, and I ordered an art carr 12 inch converter with balloon plates that stalls about 2200 rpms. I would try to get an aftermarket 12 bolt or 9 inch. Ive got the 9 inch with 3.25 gears with a rebuilt posi with better internals. I am running 29 inch tall drag radials. Ive broken 2 axles with my small block chevy, so I dont even want to think about what the caddy will do to a stock rearend. Definately tie the frame. Stiffen it as much as possible. Remember that the cadillac makes its power much lower than other engines. You can gear it pretty high and still run decent times, with engine longevity and gas mileage. I figure Im in the low 12s but Ill make sure soon, when it warms around here. My build up is a 500 with 7 inch olds rods reconditioned and arp bolts. Forged 403 olds pistons, mt 15 cam rhoads lifters, 2.19 1.84 valves in the 76 cc heads. They are ported and flow 280...205...Not bad.. Im using a ported edelbrock intake....blah which sucks...There will be a single plane available soon though. I am using a shaft rocker setup with a 1.7 ratio which was custom made. I shift at 5200 rpms. The engine does protrude pretty high with the edelbrock intake. You will need a scoop or something. And finally, the cadillac 500 with 10.1 compression and a cam and intake swap with the stock manifolds will make around 400 horsepower and like 550 ft lbs of torque. You wont need a stall converter or low low gears either. Plenty to put you into the 12s with traction. If you had a small block chevy as a comparison making the same amount of power and raced them, the cadillac would win due to the fact it makes the power much sooner in the rpm band, and it only weighs around 50 more pounds also. Just something to think about. Oh and the fact that there are aluminum heads available now...ha ha. If you have anymore questions, just email me.

 

^^^
You rock, caddytransam.

Ever run that beast in the quarter?

 

Thanks very much for the info! Mines WAAAAAY milder than yours; should still be an ox, however.

Thanks again

 

I havnt been out to the strip yet. Im thinking Ill have a time slip by May. Like I said earlier....around low 12s. The cam Im running is pretty mild though. I might get a custom grind done soon thats a little bigger. I would have before, but I wanted a smaller cam for longevity. Ill post on here when I get the results.