View Full Version : Newbie Questions about a 75 Cadillac 500ci

05-26-04, 12:01 PM
Im a Caddy newb, but have been playing around with SBCs for about 5 years.
I found a 1975 500ci with trans for 300$ Canadian in a local paper. It has 100,000 miles and is running. I am wondering what kind of transmissions you can put behind this engine? Could you put a 400 or 700R4 behind it?

If tranny swaps are a possibility, I would buy this engine, rebuild it and "try" to put it in my 78 Chev half ton. I have no idea if this is even remotely possible, if anyone out there can school me:worship: it would be great.
Thanks for any info,

05-26-04, 04:35 PM
Well, TH400s (rwd models) or TH425s (Eldos) were stock, so you could sure stick one behind it. There are a few people working on the same kind of swap you're thinking of, it shouldn't be especially hard.

lux hauler
05-26-04, 06:38 PM
The swap, from what I'm told, is pretty straight forward......You'll have to buy or make motor mounts (frame mounts), move the tranny mount and have the driveshaft shortened. The TH-400 trans is best behind these motors.......they'll stand up to the torque. If the engine you're speaking of is from a rear drive car and the tranny is the one that came out of the car, it'll be a 400.

The Maximum Torque Specialties web site has some pretty good tech tips. Check it out.

barge master
06-10-04, 10:51 AM
If you want that truck to move out like you never imagined,grab that engine!! The conversion is no big deal,with a welder and some reasonable skills. The brackets MTS sells for the mounts make it fairly easy.When I did my 73 Chevy p/u,I did encounter a firewall clearance problem on the left side because the cylinder banks are offset the opposite way.The Caddy bellhousing will bolt up to anything but a Chevy transmission. The problem with the O/D units is that the converter bolt pattern is too small for the holes in the flexplate.The Caddy will destroy those anyway. I used an adapter plate to keep my Chevy transmission, and it works well. The oil pan needs to be changed also,to a rear sump.It sounds like a lot, but you will freak when you see what that engine will do. Plus you will have something not everybody has,which is kinda cool too.

Parvell Smith
06-12-04, 07:20 PM
I recently put a Cadallic 425 engine and transmission in my 1981 Chevy long wheel base truck. It was the best thing I ever done and it was not a lot of major changes. I had purchased a 1978 deville with 77,000 miles that ran & drove like a dream, but the body was past repairing. The Cadallic motor mounts will be used on the Chevy tuck. You will have to drill one extra bolt hole. The fire wall near the brake on the truck will have to have the lip cut for about 8 inches to allow the motor to set i with out touching the back firewall. I used the Manual truck transmission brace that can be slide to any position required. The transmission brace will need one holed drilled in the center of it for the Cadallic Automatic trans mount. The distributor on the Cad. is in the front & the chevy is at the back. You may have to extend a wire to the distributor. Your should use the Radiator from the Cadiallic due to water return to the radiator on a Cadiallc. Gas lines on a cadallic run up the left side of the frame & the truck is on the right side. You will have to run to rubber gas lines across under the motor cross member ( no big deal). The difference in power and torque is like night and day. My 425 acually gets better gas mileage than the 350 I replaced. It may have to do that the motor does not have to work as hard to pull the weight I carry on my truck. I even used the telescoopic tilt steering column fro the Cadiallc along with the wheels & tires. The Cadiallic wheel bolt patter and a Chevy truck is the same. I truely love the comfort and power that i now have. Also, The wiring was not a probem.