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5.0 and 5.7 Discussion, What motors will fit my caddy in Cadillac Engine Technical Discussion; If memory serves the 368/425/472/500 are identical dimensionally engines. So they all fit. SMOG pumps did not kill power, they ...
  1. #16
    N0DIH's Avatar
    N0DIH is offline Cadillac Owners Master
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    Re: What motors will fit my caddy

    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.

  2. #17
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    Re: What motors will fit my caddy

    Quote Originally Posted by N0DIH View Post
    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.

  3. #18
    N0DIH's Avatar
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    Re: What motors will fit my caddy

    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)

  4. #19
    sven914's Avatar
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    Re: What motors will fit my caddy

    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.

  5. #20
    ramos7 is offline Cadillac Owners Member
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    Re: What motors will fit my caddy

    Quote Originally Posted by sven914 View Post
    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.

  6. #21
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    Re: What motors will fit my caddy

    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.

  7. #22
    ramos7 is offline Cadillac Owners Member
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    Re: What motors will fit my caddy

    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

  8. #23
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    Re: What motors will fit my caddy

    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....

    Quote Originally Posted by ramos7 View Post
    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

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    steelybill is offline Cadillac Owners Enthusiast
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    Re: What motors will fit my caddy

    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.

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    86fleetwood541 is offline Cadillac Owners Member
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    Re: What motors will fit my caddy

    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)

  11. #26
    86FLEETWOOD is offline Cadillac Owners Member
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    Re: What motors will fit my caddy

    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

  12. #27
    N0DIH's Avatar
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    Re: What motors will fit my caddy

    Original will be fine. But not strong, don't abuse the OD trans with the Olds 350....

  13. #28
    The-Dullahan is offline Cadillac Owners Master
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    Re: What motors will fit my caddy

    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

  14. #29
    86FLEETWOOD is offline Cadillac Owners Member
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    Re: What motors will fit my caddy

    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.

  15. #30
    86fleetwood541 is offline Cadillac Owners Member
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    Re: What motors will fit my caddy

    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

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