I have a 55 Coupe Deville which looks like I may be better off doing an engine swap due to lots of water and rust in the motor. I have found a good running and cheap 425 cadillac with a turbo 400 trans. Has any one ever done a similar swap? If so, any advice what to do, or not to do. Thanks, CrazyVern
you didn't throw away the '55 hydra-matic,did you? that's one of the good ones,you might be able to sell the core.
how much water and rust? older engines can be bored out a lot more than the newer "thin-wall" style castings.
A 425/ th400 will push the car down the road nicely, if you change the rear end out to a 2.73 or close. With the stock rear end, It couldn't handle highway speeds for long. You'll have to notch the frame crossmember to get the oil filter to fit, and maybe even get a larger radiator. You'll have to modify the transmission mount and drive shaft also.
have to disagree about the rear end comment i put 40k on my 55 the rear end was beautiful i sat at 7o mph on 6 hour trips with original motor ****** rear end and it didnt mind it at all.
You can do it with the original motor and ******, but the 425 don't like to rev very high, and the TH400 is only 1:1 ratio in top gear. A 425 floats the valves @ around 4200 rpm. I've got mine set up now to cruise at 70mph @ around 2300 rpm.
I'm considering a similar swap in my '55 olds. ***uming your car is like mine, you'll need an oil pan with a rear sump(eldorado) and do something about the oil pump/filter clearance. I haven't tried the 425 pan, but it's a mid sump & I don't think it would work. Also the ****** crossmember & driveshaft mod's. I think it's very do-able and a great idea! I'm worried about my stock rearend holding up to the (advertised) 535lbft of torque that my 500ci will be putting to it! I figger on just running skinny tires! Also, the caddy 425's are lighter than the 472/500 engines by a little, and have the good pully/***ecory drive w/no smog pump. Also, if a 500ci is found later it's a direct bolt in swap for the 425. PLEASE KEEP US POSTED ON YOUR SWAP!!! 52RustRocket... have you done the caddy swap in yours? If so, I'd love to hear the details. Later- John
Yeah, It's got a 425/TH400. The engine/****** combo was "in" the car when I bought it, but I had to do quite a bit of minor stuff to get it all to work right. They had put on an oil filter relocation kit and mounted the filter to the firewall. It looked ****-***ed ugly, so I notched and boxed the front crossmember to accept the stock oil filter location. The radiator they had in it was a single core from a later model Chrystler. I drove it a few days on short trips to test everything out and found it to over heat rather quickly. I them bought the largest aluminum radiator I could fit across the front, but had to fab up an all new core support to hold it. I also had to go with two 12" electric fans because the radiator had to be mounted low enough to let the hood close, hence the stock fan was too high to do any good. I drove it like that for a few months before I decided to change the rear end to a '69 Impala with 2:73 gears. I could now cruise comfortably for how ever long of trip I wanted to make.
Here's how I put a 500/TH400 in a 1957 coupe de ville. It's a very similar swap to what you're looking at. http://www.donshotrodpage.net/Project-57/Page013.html
I put an Olds 455/th400 in mine. The ***** is drivers side starter/exhaust/steering box all trying to take up the same space. It runs down the road nice at around 3500 rpm .
DRD57, I'm on page 18 right now on another browser window, that is how a car is built! I advise everyone to go to that link & read that stuff! Ok, gotta get back to my readin'........ Later- John
My 56 Coupe has a 500 caddy and a th400 in it.I'm busy finshing off the loose ends before it goes in to get the interior done.Here's a pic of the new 500 just after it was bolted in. crazyvern ....when yer get tired of the 425 the hotrod 500 caddy will drop right in ,make that caddy get up and walk!
Everyone, Thanks for all the advise. DRD57 that's a very cool website and just what I needed to know. I also found a 75 cad 500/turbo 400 yesterday, so it looks like my 55 will be getting a 500 instead of the 425. On the questions about the 331 and water damage, I still have it, but it was left with the hood open and no air cleaner on it. Two cylinders were totally filled with water and over time they must have let water leak past the rings filling the rest of the motor up with water, so everything in the engine is rusted and pitted to some degree. I am going to clean it up and see exactly how bad it is but I going with the cad 500/turbo 400 drive train. CrazyVern
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