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1983 Cadillac Fleetwood
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I just got done putting a 500 in a 83 fleetwood. This project has been nothing but a pain in my rear since the start.The first big problem was the oil pan. I needed the sump at the rear and this one was at the front. So i took it to work and cut it in half flipped it around and tig welded it back together. Then i had to extend the the oil pick up and tig weld it back together. Then the motor mounts, I had to drill holes in the engine cradle and then notch them to fit the mounts on the 500. the torque converter on the over drive trqanny would not bolt to the 500s flywheel so i had to change the tranny. I went with a bop 400 turbo. I had to shorten my drive shaft and move the tranny mount. The motor is in now and it was a little tighter then i thought it would be, but it does fit. Dont let anyone tell you that it will go " right in " bc it didnt for me anyways. If anyone knows what the oil psi is supose to be on the 500 , it would be real helpful. Its a 76 500 out of a fleetwood. Im glad i did the 500 project bc the car is a tire burnin machine now. It used to have the ht 4100 in it which was a real dog.
 

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95 FWB 81SDV 96 FWB 94 Fleetwood
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It's too bad you did not get a 77-79 full size caddy as a donor car.. the oil pan and trassmission and drive shaft , crossmember...every part you need is a bolt in off that car... motor mounts ...you did a lot of extra work... but its a good thing you went with the th400... that 200 4R would not of lasted long...
 

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95 FWB 81SDV 96 FWB 94 Fleetwood
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Oh I forgot one thing the rear end is different . so the drive shaft would not have been a bolt in.. but you could swap the rears..
 

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'80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
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The whole entire swap process has been posted here several times. It is also in junkyard interchange books and has been for years. No it isn't a direct bolt-in swap. Your engine mount problem makes no sense to me though. There is an aftermarked flex plate out now to address the torque converter problem. I used to drill extra holes and use washers with 1/3 ground off to deal with the holes being right next to a step. Then, you still need to hook up the detent cable or the trans will blow up in 5 minutes instead of 1 hour. Better off with the TH-400. Now you need a posi to take advantage of all that torque.
 

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'80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
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It's too bad you did not get a 77-79 full size caddy as a donor car.. the oil pan and trassmission and drive shaft , crossmember...every part you need is a bolt in off that car... motor mounts ...you did a lot of extra work... but its a good thing you went with the th400... that 200 4R would not of lasted long...

The driveshaft from a 77-9 should be avoided. The 1980-81 is a much better choice as the CV joints are gone. Lighter and less work to keep it alive. Crossmembers don't need to be swapped at all. If anything grab a crossmember from a later LT-1 full sized RWD as they have 2 humps for dual exhaust.
 

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95 FWB 81SDV 96 FWB 94 Fleetwood
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Apeman... thats true about the driveshaft.. I have a 472 in a 81 deville.. but the 81 driveshaft is a tube in another tube with rubber in the middle.. I had balance problems with mine so I had Denny's make me a new one... And for the crossmember , thats what I did... I got a new 94-96 fleetwood crossmember for just over $100 and all I had to do was drill two holes in the frame for a bolt in..
 

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1983 Cadillac Fleetwood
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5 Posts
Discussion Starter #7
Thanks guys for all the info. Do any of you know the oil psi on the 500. I was going to turn the oil pump over with a drill through the distibutor before i start this thing to make sure im getting oil.
 

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'80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
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80/81 driveshaft durability tested with 500 for many years by myself and a few other Cadillac patriots. Twist it with 550 foot lbs mulitplied by TH-400 and it will hold up. Take the car to a garage where some idiot places it on the center post lift and contacts the driveshaft and it's all over.
 

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Nitrous03DHS,AJtune,Corsa,Volant,3.71s,Grille,tinted,stall'd
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305 Posts
I just got done putting a 500 in a 83 fleetwood. This project has been nothing but a pain in my rear since the start.The first big problem was the oil pan. I needed the sump at the rear and this one was at the front. So i took it to work and cut it in half flipped it around and tig welded it back together. Then i had to extend the the oil pick up and tig weld it back together. Then the motor mounts, I had to drill holes in the engine cradle and then notch them to fit the mounts on the 500. the torque converter on the over drive trqanny would not bolt to the 500s flywheel so i had to change the tranny. I went with a bop 400 turbo. I had to shorten my drive shaft and move the tranny mount. The motor is in now and it was a little tighter then i thought it would be, but it does fit. Dont let anyone tell you that it will go " right in " bc it didnt for me anyways. If anyone knows what the oil psi is supose to be on the 500 , it would be real helpful. Its a 76 500 out of a fleetwood. Im glad i did the 500 project bc the car is a tire burnin machine now. It used to have the ht 4100 in it which was a real dog.
COOL:thumbsup:
 

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74 Eldorado
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149 Posts
Hey Ozzzy, I'm from Toledo and so is my 74 eldorado...... What side of the river are located?

Congrats on the swap....Can wait to get to work on my motor over the winter, trying to sell my elcamino first then its on....

Take Care
 

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84 Coupe w/500
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5,665 Posts
I tried looking through the search feature for 7 pages, my eyes hurt and I'm tired. I'm putting a '76 500 in a 90 brougham. The 500 has a mid sump pan, from what it looks like. I was wondering if that is the correct one to use. I've read that theres a front, mid and rear...is that right? Also, the 77-79 will have all the necessary parts or will an 80 have the parts?
 

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'85 Fleetwood FWD
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728 Posts
The info I have here is that normal oil pressure on 472/500 is 35 to 40 PSI. Not a lot, but it seems to work fine. It's not like the old days (50s) when we thought the pressure should be 125 PSI :cookoo:
 

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Eldorado
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448 Posts
The TH400 is the way to go, but the 9" tail section needs a shorter drive shaft. A 4" tail section has allowed me use the same drive shaft, but converting a trans requires complete disassembly. Check your rear axle ratio; might not be best for a non overdrive trans. Bruce Roe CLC # 14630
 

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84 Coupe w/500
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I have 3.73 gears in the rear. I'm not looking for gas mileage, I want to build more towards performance. Is the mid sump pan going to work?
 

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Eldorado
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With a 500, the only place you can really use 3.73 gears is on the dragstrip with slicks. The low reving engine will red line before 100 mph. A 2.73 gear would be lot more practical. Bruce Roe
 

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'85 Fleetwood FWD
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728 Posts
With that much torque you can get away with even a 2.56. My El Camino had a 2.56 with a built 400, which had great torque, and performed great.
My '76 Coupe Deville had a 2.73, and seemed "light on it's feet" for a 5300 lb car.
In my current El Camino project, ('75), I have a Currie 9 inch Ford rear with a 2.50 rear ratio, with a built Caddy 500. The car weighs 3750 stock, and the 500 is about 60 lbs heavier than a small block Chevy.
 

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84 Coupe w/500
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Thanks for all the info...I started a similar thread in the RWD forum so I have to get back over there before talking about much more. Jay said he was gonna keep it over there for us. I was unsure about the best year for a donor and the pan. Thanks again
 

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84 Coupe w/500
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Hey we were wondering about the oil pan, I have a mid sump now. Is that gonna work in the 90 FWB? I thought I read that it would work but cant find that info anymore.
 
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