: What motors will fit my caddy



86FLEETWOOD
09-10-09, 12:21 AM
What motors will fit a 1986 fleetwood brougham? i have the 140 hp 307-y. What all will i have to change if i replaced my 307

sven914
09-10-09, 05:13 PM
You can down grade into the less powerful, but more fuel efficient HT4100 (82-85 RWD's) and still keep your transmission. You would have to get the electronic hardware off the 4100 car because you will be going from carburetted to fuel injected.

You could go into a 368 (80) (had the V8-6-4 function for 1981) and will have to change the transmission. The 368 will only bolt up to a 3-speed.

You could also go into a Buick 250 Six Cylinder (80-84)and would have to change transmission.

Another option is the Chevrolet 305 (91-92), which would give you the same benefits as the 307. It has TBI so you would need the computer to control it and a new transmission.

The most popular change is to the Chevrolet 350 (L05 90-93/LT1 94-96). The L05 350 engine used by Cadillac was TBI, but you can get a carburetted one from an 80's Caprice. It would probably the easiest conversion, to go to a 350 with a non computer controlled carburettor and remove your computer from the system. The 350 too will require a different transmission.

Whenever you are upgrading in engine power, you need to change the rear axle ratio. Also the engine/transmission mounts may be different for the different engines.

86FLEETWOOD
09-11-09, 09:13 PM
Thank you for the information. My current engine is 307 vin y. I read that i can rebuild it as the 307 vin 9 which has more horsepower. would i be able to use use the same computer? i will have to change the rear axel ratio also as well, right?

sven914
09-12-09, 12:00 AM
I don't believe you need to change the rear end if you do that (I think the stock one was built to accommodate the extra horse power). But if it concerns you, then it wouldn't hurt to install the final drive from an 88+ (with a 5.0 engine), which has a larger ratio.

To modify the "Y" engine, you need a performance cam, stiffer valve springs, a larger vibration dampener, and a high flow carburetor. "9's" also came with duel outlet exhaust, so you can get a new exhaust system installed. Being that the "9" still used a feed back carburettor, you may need to change the computer (otherwise it may starve the engine and throw rich codes).

86FLEETWOOD
09-12-09, 07:16 AM
Thanks alot, you really know your caddys:bouncy:

brougham
09-20-09, 04:31 AM
Unless you want to change a lot of parts you'd be better off staying with an oldsmobile engine.

RocketFast321
09-21-09, 03:48 AM
Stay with olds. Since you have a olds 307, you can put a olds 350 in. Just swap everything off your 307 to your olds 350. Intake and all 50' of vacuum lines.

Aron9000
09-21-09, 03:53 AM
I'd look for some performance cylinder heads, intake, headers, true dual exhaust along with a mild cam if you are going to do an Olds 350 build. Might as well do it right if you're going to swap the motor. That would be a fun combo with at least 300 crank hp.

N0DIH
09-22-09, 12:18 PM
If it was me? Go spend $800 on a used 5.3L LM7 out of a newer GMC/Chevy truck. Get the trans too. It is a bigger swap, but you will LOVE it.

Why use old engines that struggles to get to 300 hp when a 5.3L is 300+ out of the box.

If fuel economy is more important, a 4.8L is a bit better, but being they make less of them, probably more expensive.

If power is the game, then get a 6.0L LQ4 or LQ9.

Yes, these are a bigger project, but if you are wanting a modern high fuel efficient engine that will keep your Cadillac living on forever, this is the investment I would seriously look into.

Car-part.com and look up a 50K mile engine or so, you will be surprised how inexpensive they are compared to doing something like an LT1 or L05 or an Olds 350 swap. Not as easy, but far more rewarding.

86FLEETWOOD
09-22-09, 10:25 PM
What else would i have to chage w/ that motor swap.

N0DIH
09-22-09, 11:56 PM
With Gen III or Gen IV Engines, would be fun.

What I DO know is the oil pan will need mods (and don't start with a Corvette oil pan), use truck manifolds (they appear to be closest to fit), you will need custom engine mounts, but by now they might be available from someone.

You will need to mod it for EFI, so you will need the pcm a to be able to tune it (I can do, so for me not an issue). So no carbie anymore. So you will need a high pressure fuel pump in the tank, you have to hunt around to find radiator hoses and heater hoses that will match up.

It isn't the simple projo like a 350 Olds swap which is very very simple (Did that one on my 85 Cutlass). But the rewards are great, but the work is much more. Imagine having brand new car drivability and fuel economy like mid 20's highway and high teens city. And have power that would be phenomenal for a big car.

N0DIH
09-23-09, 12:07 AM
Spend some time reading: http://www.ls1tech.com/forums/conversions-hybrids/1075693-my-budget-ls-engine-swap-guide-1500-a.html

sven914
09-23-09, 10:11 PM
If your going to go through all that trouble; why not drop in a Cadillac 500? at least that would save you the electronic headaches.

Theoretically the 500 should fit fine. The 80-81 Cadillac RWDs (with you body style) had the 368 engine. The 368 was a 77-79 425 block, re-bored for economy. The 425 was based on the 472's block, 68-74. The 472 was an undersized version the 500, used from 1970 to 1976. The 500 is the world's largest and most powerful (400hp for 1970) gasoline motor, ever offered in a passenger vehicle.

Why waste you time with a new engine that struggles to make 295hp (Chevrolet 1500 series specification for the 5.3).

N0DIH
09-23-09, 11:52 PM
It has 295 hp is weakest form (first year) or so, got up to 315hp. It makes this power with a tiny cam, and you will NEVER get 25+ mph on a 500 Caddy no matter what you do.

All depends on what you want. Power and Economy, the Gen III/IV GM engines. Power, old school gas guzzling V8's. Sure, you can do well with a 500, but in this economy, you are going to going to spend around the same amount of $, might as well get something that rocks on mpg and runs great has AWESOME driveability and ability to make 400 hp very easily and still knock down great mpg. The 500 will just never do it.

Honestly, I have given up on "old school" engines for the modern economy and power.

Look at the engines like this.

The Olds 307 never made over 180 hp in HO form, 140 hp in std form. Cam in the 180 duration range.
The L05 305 Chevy made 210 hp.
The L99 (the 265 CID LT1) makes 200 hp with fast burn heads, reverse cooling and 10:1 compression.
The LT1 5.7L makes 260 hp with fast burn iron heads and same cam as above (195 or so intake duration)
The LT1 5.7L Corvette/Firebird/Camaro engine makes 285-300 hp with 10.75:1 comp alum heads, and a bigger cam, (202 intake duration/207 exhaust)
The LT4 5.7L Corvette engine makes 345 hp (considered underrated to not overshadow the LS1) with a 203 intake / 210 exhaust duration cam.
The LS1 5.7L makes (in 2004) 350 hp and 365 lb/ft torque with a 197/207 duration cam. The LS1 and LM7 (5.3L) are virtually same engine, LS1 having bigger bore.
The LM7 5.3 Vortec truck engine is 285 hp with a 190/191, 0.466" / 0.457" on a 114 LSA cam. That is one small cam to make that sort of power with only 5.3L.

So lets take a 76 500 Cadillac, with around the cam cam specs as a LS1, made a pathetic 200 hp. And the LS1 made 350 hp.

$ for $, take a LS1 and you take a 500 and I will make 500 hp easier and cheaper. And have much better fuel economy and drivability. The amount of work to build a 500 up would be very expensive. You are talking an engine that had its last update in 1983 or so. The LS1 engines are new from the ground up.

To each his own, I would keep my options open. More work to put in newer engine, but far more efficiency and better emissions. But it isn't a no brainer drop in swap. A Cad 500 would be a fairly easy swap in comparison.

sven914
09-24-09, 05:55 PM
So lets take a 76 500 Cadillac, with around the cam cam specs as a LS1, made a pathetic 200 hp. And the LS1 made 350 hp.



To each his own, I would keep my options open. More work to put in newer engine, but far more efficiency and better emissions. But it isn't a no brainer drop in swap. A Cad 500 would be a fairly easy swap in comparison.

I though about it a little longer and my theory about the 500 fitting in fine wasn't exactly correct. The largest engine that could go in to your car, without any modification to the dimensions of the engine compartment is a 425. The 472 and 500 are big block motors, so you will have to increase the size of the engine compartment to make the fit. I don't know by how much and what, if anything, you would have to sacrifice to make the fit.

Someone on the RWD forum asked about putting a 500 in a 90 Brougham (http://www.cadillacforums.com/forums/rwd-19xx-1984-deville-fleetwood-1985/171653-redorectto500.html); the discussion might be useful.

As for the 76 only being able to make a pathetic 200 horsepower; to meet emission and fuel mileage requirements, Cadillac was forced to reduce the compression. 500's after 70 were also equipped with a smog pump, which killed their power. 1970 was the only year they made 400hp.

N0DIH
09-24-09, 07:04 PM
If memory serves the 368/425/472/500 are identical dimensionally engines. So they all fit.

SMOG pumps did not kill power, they have nothing to do with power, they take minimal hp to spin (grab one and spin it by hand, you would be hard pressed @ 5000 rpm to hurt 2 hp).

Oh the things GM did to kill hp, retarding cams, small cams, small cams retarded, garbage heads, dismal compression, dismal compression with garbage heads, restrictive intakes and crap port designs, pathetic log manifolds, very restrictive exhausts, etc. And poor tuning to go with it.

So yes, you can fix a 500 to make killer power, you can hide a 500 under a 368 air cleaner and no one will be the wiser, you can leave on a smog pump to give the impression of slowness, it can be fun, but it is still a 575-600 lb engine too in a heavy car. The LS1 is a lot lighter, and it will make the car much more nible and agile too. Losing weight on the front end of these beasts is WONDERFUL improvements in handling and braking.

Just try, relocate the battery to the trunk. You will be in awe the improvement. 50-70 lbs front several inches in front of the CG, to several FEET behind (locate to right rear as FAR back as possible) and then go driving. You will be in awe how much it helps. It changes the CG of the car to similar of that of moving the engine BACK 10 inches in the frame rails, which we usually cannot do.

sven914
09-24-09, 08:25 PM
If memory serves the 368/425/472/500 are identical dimensionally engines. So they all fit.


the 425 was over 100lbs lighter than the 472. It was slightly smaller, so they had to have changed the dimensions. Maybe for economical reasons they cut out some of the dead space between the cylinders.

472 and 500 motors had a bore of 4.3". 425 motors had a bore of 4.082". Thats a .218" difference per cylinder, which is an overall 1.744" of extra dead space in the entire engine. I don't know what the original cylinder wall thickness was for the 500, but I would imagine that there was too much extra metal.

N0DIH
09-24-09, 10:23 PM
Nope, Cadillac lightened the 425 by making shaving weight everywhere, not by downsizing. Don't guess. They share a LOT, heads, intakes, exhaust manifolds, etc. Look closer. It is easy to lighten thing, which is why you don't see anyone racing a 425 or 368. They took so much out of the crank it it can't handle the power. 368, even more pulled out. IIRC the 500 cam were the same cam on the 425 and 368. Go lurk the 500 forum on here. The problem with the lightweight 425 and later castings is they were crack prone and failure prone in performance use. The Cadillac guys who build mammoth engines warn about using the 425 pieces.

It isn't that easy to simply redesign to make a whole new engine, it takes a LONG time to get money back out of the tooling changes, and designing a new engine from the ground up is stupid costly. GM wasn't spending money back then. The 4.1L was coming and they were focusing on that.

These are engine FAMILY's. Pontiac and Buick made short deck engines, Pontiac in 1978 on the 301 and 265 and then Buick in 1995 on the Series II 3800. Cadillac didn't. So with the 301 and 265, they can share nearly everything across the engine line, except the intake (assuming the ports still match, like on the 301, they don't)

sven914
09-25-09, 06:13 PM
Well thats good. My project idea of taking an 80-85 Coupe de Ville/ Fleetwood Brougham Coupe and putting in a 500, built to 1970 specifications is still alive.

ramos7
09-30-09, 04:41 AM
To modify the "Y" engine, you need a performance cam, stiffer valve springs, a larger vibration dampener, and a high flow carburetor. "9's" also came with duel outlet exhaust, so you can get a new exhaust system installed. Being that the "9" still used a feed back carburettor, you may need to change the computer (otherwise it may starve the engine and throw rich codes).

in order to make it a vin 9 engine youll need a set of 5A heads and A4 intake along with the parts you listed. the Y engines heads swirl ports are too small to make any real power and can only be used with the stock intake. if you get a set of 5A heads you can use an edelbrock intake. if it was me id just find a 350 rocket or a 403. the extra torque will launch this big boat.

N0DIH
09-30-09, 12:14 PM
There is an article on how to make a 307 scream in one of the latest mags, 500 some hp.... Not streetable in a heavy car. But they used the 5A heads too.

If I was itching to do an engine swap, I just found a couple 5.3L truck LM7's for $400 each. BOTH with under 50K miles. That is like a new engine. $ for $ you can't beat it. Yes, some work to put in, the biggest headache is the oil pan, then the wiring and fuel pump. But nothing insurmountable.

Lets think of it this way, the LM7's move a 5.3L to around a 16.0 quarter mile or slightly better with a 5000 lb truck, and a friend of mine towed 9000 lbs all the time with his with an effective 3.42 gear (with our tire sizes, he had 3.73's). If you are swapping in a gear 3.73's would be a wonderful gear in a Fleetwood/Brougham. So you are faster than the best 307 GM ever made, can tow with a LT1 V4P, probably out run an LT1 with relative ease and knock down excellent fuel economy.

If anyone has looked, the car manf have gone to GEAR to move the cars not torque. Peak torque is where best mpg is, but the more torque is more fuel used. So we have gone to let more gears and shorter gears get the car moving and still give excellent performance.

ramos7
10-02-09, 03:09 AM
the gearing has crossed my mind. at one point in time i thought swapping in 4:10 gears from a chevy truck to see the results but in this economy i havent been able to play with my toy lately

N0DIH
10-05-09, 12:26 AM
With the 307? It will help a lot, but then you will find how small the cam is. Then you could simply toss in a 307 HO cam or find an Olds roller grind that works ($$). I can find out what is out there.

If you can go back to non roller lifters (might be able to using Mopar lifters) you can get a better grind that would better suit the 307 and 4.10's.

Toss on some old 5A heads ported and milled to get comp up would help too.

It will never run "right" as it is just a small engine....


the gearing has crossed my mind. at one point in time i thought swapping in 4:10 gears from a chevy truck to see the results but in this economy i havent been able to play with my toy lately

steelybill
10-30-09, 11:55 PM
A stock rebuilt '76 500 made 302 hp on a dyno test, The specs in the aftermarket manuals, like Chiltons etc, is less than 200 HP because of the standard being changed in 1972, to rear wheel HP with all accesories operating. Don't know how the new engines are rated.
The 400 HP of the '70 Eldo is a myth. Valve float wold take over before it ever got to the RPM the factory claimed. It did look good on paper though. Typical of manufacture's claims.
The '76 500 is a good engine though, and likely the last good one that Cadillac designed. It does like gas very well, and it's a torque monster, and a transmission like a 200-4R will not live long behind it.

86fleetwood541
11-08-09, 12:58 AM
I am trying to figure out this same thing and sofar what ive got from chris I beleive his name is at cad500parts is with their engine mount kit an eldo oil pan and the headers off a a 475or 500 from a deville or any cad but the eldo and a chassis mount oil pomp and a phew other small changes this engine is a direct bolt in for these cars (fleetwoods of the 80)

86FLEETWOOD
11-19-09, 10:45 PM
I now have a 350 olds motor from a 1976 cutlass. Do i need its tranny also or can it go to my original tranny

N0DIH
11-19-09, 10:56 PM
Original will be fine. But not strong, don't abuse the OD trans with the Olds 350....

The-Dullahan
12-02-09, 04:21 PM
I have seen a 1980 Fleetwood Brougham with a 500 in it. Your car is generically, basically the same.

http://www.mcsmk8.com/80CAD-500/MAVICA.HTM

86FLEETWOOD
01-04-10, 06:13 AM
now i have someone searching for a motor for my caddy. i have been looking into an olds 350, 403 or the pontiac 400. these motors are being salvaged out of 70's model cars. which one if any would replace my 307.

86fleetwood541
01-05-10, 07:33 PM
the oldsmobile 350 403 and 455 will all be bolt ins although the 455 sits around 1 inch higher because of the intake and can cause clearence issues the 403 and 350 dont cause this the cadilac 425 472 and 500 will all go in your car however you will need a different transmission driveline and rear end the drive line might work with different yokes from what I understand however the rear end needs switched because it is a full in smaller a 7.5 vs an 8.5 out of the earlyer years the 7.5 wont handle the kind of torque you would be putting to it plus the gears are wrong for the 400 tranny you would want to handle the torque btw everything bolts in except engine mounts but you can buy a mount kit for our car from flashcraft(cad500parts.com) for 95 dollars plus shipping I personally am installing a 472 in mine or will be shortly i should say however the oldsmobile engines will be the easiest direct swap If i whent that route I would go with the olds350 get some head work a mid performance cam exhaust and a stage 2 master rebuild kit for that 2004r so it will handle the power from the 350 I would get the tranny kit even if I didnt have any work done to the 350 anyway google 2004r raptor transmission they sell rebuild racing kits for the 2004r allowing it to supposably handloe 800+ ft,lbs. of torque

N0DIH
01-05-10, 08:05 PM
don't knock the 7.5" too much, it lives behind LS1's in the F-Body cars.... Just don't tow or put slicks on, allow it to smoke the tires if it does, when you load it up with traction, that is when things break....

I have a 8.5 3.08 open 9C1 axle (rear discs) for sale if you are interested though.....bolt in for any 77-up B/D body.....

86FLEETWOOD
02-04-10, 09:17 PM
I kow have a chevy 350 w/ the 700 tranny. Gonna put it in my cadillac this weekend. Anyone knows how long it should take and what i should be faced with?