: Can I put a CADILLAC 500 V8 engine in my Deville?



83cadillac
02-19-06, 01:46 PM
i would like to put in this 8.0L engine in my 83 deville. This engine was found in the 75 and 76 cadillacs. If so what changes would i need to do to make it fit and work with the car.

DaveSmed
02-19-06, 02:49 PM
Find an 80-81 Cadillac (RWD of course, no Eldos etc.) as a parts source. They came with the 368 cid engine, which is the same block as the 500cid, making it pretty much a bolt in swap! You might be able to use some stuff off of earlier cars too, but i'm unsure what works and what doesn't.

davesdeville
02-19-06, 05:06 PM
You'll need a short tailshaft TH400 trans (77-81 RWD Caddys, and other cars.) You can use the motor mounts from a 77-81 RWD as well. Your rear is either 3.42 or 3.73 I think, 7.5" - it won't last too long behind the torque of a 500, and you'd be better off with something like 2.56-3.08s if you ever want to take it on the freeway. With 3.73s it would be at 3800rpm at 85mph (assuming 28" tire) which is quite unhappy... it would accelerate like a bat out of hell to 85 though.

83cadillac
02-19-06, 08:40 PM
What spesfic things would i be doing with the car besides a new trasmission and rear end? Is there a way to fiqure out the electrical and keep the computer the same or would i have to exchange that also?

CoupeDevilleRob
02-19-06, 09:01 PM
The 500 is carbuerated (most were anyway) so the computer doesn't matter. You'd need to leave it in the car though so the climate control works.

eldorado99
02-19-06, 10:37 PM
Not to Hijack the thread or anything but what size rearend would he need? (What size did the 500 Cad's usually have?)

The Ape Man
02-19-06, 11:04 PM
http://www.cadillacforums.com/forums/500-472-425-368/48306-472-1983-deville-swap-done-pics.html

Keep the compuker so the climate control works as mentioned. Rear axle should be swapped to low 2XX numerical as mentioned.

Best way to get this done is with a 425 RWD parts car parked next to it.

I once wrote this whole thing up on here one end to the other with all parts listed.

Fleet
02-20-06, 02:03 AM
i would like to put in this 8.0L engine in my 83 deville. This engine was found in the 75 and 76 cadillacs.
Actually, the 500-cu-in engine is 8.2 liters.

N0DIH
02-20-06, 01:05 PM
Dave, I don't agree with you 100% here. Why? You can't hook up with a 3.42 rear and a 500, so unless you are running drag slicks, you won't ever PUT enough power into that gear set to hurt it. MANY of LS1 powered Z28/TA's have this very rear gear and live in the 11's.

But towing would likely do it in fairly fast. Keep under 2000 towing with the 7.5". Get and 8.5" and you can tow up to 7000 lbs properly equipped.

Agreed on gearing though, unless you put in an OD (THM200 4R built!) the gearing will waste fuel and the engine, it won't appreciate spinning so fast all the time.

Summary: Don't rush to swap the rear end, don't make it a show stopper. You can snag a 90-93 Fleetwood/Brougham rear with 3.08's easily and they are 8.5" rear, and will live longer under harsh use.

Talk to the guys at Maximum Torque Specialties or Cadillac Motorosports about gearing and cam selections. But with low buck stock cams, 3.08's is probably the lowest you would dare go, 2.73's or 2.56's would be more enjoyable for cruising.


You'll need a short tailshaft TH400 trans (77-81 RWD Caddys, and other cars.) You can use the motor mounts from a 77-81 RWD as well. Your rear is either 3.42 or 3.73 I think, 7.5" - it won't last too long behind the torque of a 500, and you'd be better off with something like 2.56-3.08s if you ever want to take it on the freeway. With 3.73s it would be at 3800rpm at 85mph (assuming 28" tire) which is quite unhappy... it would accelerate like a bat out of hell to 85 though.

CoupeDevilleRob
02-20-06, 09:15 PM
This is something I think is overlooked a lot when discussing this engine swap, what about suspension mods/upgrades? A 500 weighs a hell of a lot more than a 4100. That car's front suspension was designed to carry a much lighter engine. Would you need heavier springs, sway bars, etc. to compensate for the increased weight? I would imagine the car would plow through turns with all that extra weight up front riding on the stock suspension. Any input?

eldorado99
02-21-06, 01:59 AM
I don't know how heavy a 4.1 is, but the 500 is only like 650 pounds is it not?

The Ape Man
02-21-06, 08:53 AM
Front springs will need to be changed.

davesdeville
02-22-06, 09:06 PM
Dave, I don't agree with you 100% here. Why? You can't hook up with a 3.42 rear and a 500, so unless you are running drag slicks, you won't ever PUT enough power into that gear set to hurt it. MANY of LS1 powered Z28/TA's have this very rear gear and live in the 11's.

Yes, most street tires are going to break traction before the rear eats it. But I figure if you're going to bother put a 500 in there you're probably going to run some kind of performance tire, whether it's a max performance summer tire, drag radial, et street, whatever. LS1 F body examples don't really work too well... this car will be over 4000lbs and pushing near or over 500ft.lbs. at the motor. It's probably not going to hurt to leave the 7.5 in there, it'll grenade eventually, you can upgrade then.

lecabz
02-27-06, 11:53 PM
what rear end could i use in a 91 brougham to take off faster it a 91 but have a 85 rearend in the garage(4100 motor car is that ratio high so i can take off burning rubber?