425 vs. 500..... hot-rodding.... need some opinions... - Page 2
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500, 472, 425, 368 Discussion, 425 vs. 500..... hot-rodding.... need some opinions... in Cadillac Engine Technical Discussion; Originally Posted by lux hauler When was the last time you seen a dump truck with car gears, car trans, ...
  1. #16
    JTraik is offline Cadillac Owners Enthusiast
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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    Quote Originally Posted by lux hauler
    When was the last time you seen a dump truck with car gears, car trans, car tires.........
    This is true. But still...the car only puts out 220 ftlbs....the pictures dont lie... i just dont believe it haha! That is a sick burnout tho!

  2. #17
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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    I think you mean 320ft lbs

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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    If you want better power and fuel economy from the stock 425 it has to breath I just put a 14" edelbrock open faced breather along with the highflow muffler and I don't care what they say that 180hp rating is dead wrong my 77 can run with the best of them. If I was in you situation I would build up the 425 it's easy to work on and all it needs is a manifold intake and exahust a good carb and a good set of pipes and you'll get to the low 15's maby into the 14's.

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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    Well, this is what else I was thinking....

    If I decided to buy some hi-po parts for the 425, such as the Edelbrock intake manifold, cam then the nice true dual exhaust etc.... it would be a cheap way to get more power....

    THEN, since I woudln't be running the car like that for a long time, I could get the 500 rebuilt (I actually want to get both of them soon.... for the price, like people are saying... they are getting more rare) Actually, they might even be a 472... I think they are a 500 though... either way, the crank is the only difference....

    but what I was thinking is, once the 500 is rebuilt and beefed up, I could swap the intake manifold over... there coudln't be much use on the cam at that point, so that could be swapped as well, and since they are pretty much the same engine, my nice custom dual exhaust should be able to bolt to the exhaust manifolds on the 500 as well....

    ... besides buying the engine, it would bring my inital cost wayyyy down.... honestly, if that car was running low 15 with those simple bolt-ons, I would be more then happy... I havn't taken it to the track yet (I want to before engine swap, or any work gets done, to get a before and after check) but if I was to guess, I would have to say the car would run 18seconds or so in the 1/4..... which is why shaving 3.5+ seconds off the time from those bolt-ons dosn't seem that easy....

    ...I guess I have decided that I would like to get the 500 and build it up... but for now, if I decide to get some of the performance parts... I would get the carb rebuilt, that can be used on the 500 too, the intake manifold can be used.... would it be safe to re-use the [new] cam? we are also going to hollow the cat out too.... damn thing is just so quiet for a big block V8...

    and without getting into too much detail.... what are some basic upgrades with the 425/500 that would be a good star? I have the intake manifold and cam... I was going to keep the factory exhaust manifolds as I heard that it isn't worth the trouble of trying to find a decent set of headers that are designed for car use (not hot rod) when I go to get the 500 rebuilt, I'll let the machine shop guy do his tricks with the engine (he built up a 472, but converted it to a 500 and put it in his fathers '68 DeVille... stock intake manifold too.... says the thing just screams) the idea of this is to be low budget... so that when you look at the car, it will look like an old Cadillac, but beat a Mustang at the track

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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    oh, and I could care less about fuel econemy... plus I heard that people are getting 12-14mpg with a built 500 if geared correctly... I get 12mpg as of now, so I really woudln't be loosing anything...

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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    What would i have to do to get AC to work with the Edelbrock intake manifold? the current compressor (A-4?) will not bolt, but I heard that the 1980+ compressor will... any help?

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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    I believe MTS has some sort of brackets to do that, Wolf. BTW that car is a lot nicer looking than you've made it sound. It's cool to see all you young dudes who like those cars. When I was 16 my 1st car was a 67 Lincoln coupe, I was the only young guy in town who drove a big tanker like that. I liked 'em then and I like 'em now. That's why I'm the Barge Master. Good luck.

  8. #23
    lux hauler is offline Cadillac Owners Connoisseur
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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    Quote Originally Posted by Night Wolf
    What would i have to do to get AC to work with the Edelbrock intake manifold? the current compressor (A-4?) will not bolt, but I heard that the 1980+ compressor will... any help?
    I'm not sure you'll get the compressor to fit under the hood with that intake. Might want to do some measuring.....the carb and intake will be close too. The Edelbrock is about three inches taller than the stock intake.

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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    IIRC from an e-mail I sent, Bruce (Ultra Slow on the board) used his stock compressor.... I think in 1980 they changed it, he said that is fit without a problem and works great... so all I would have to do is get the 1980 style compressor and hook it into the system? it is compatible with everything else?

    as of now, the AC dosn't work... out of freon, so we are going to switch it over to R-134A... but if I need to change the compressor, it'll just wait...

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

  10. #25
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    Re: 425 vs. 500..... hot-rodding.... need some opinions...

    I would not waste my time hotrodding a 425 for what your doing
    the 425 rebuilt with good parts is great for mileage and towing but not for motivating a land barge
    do at least a 472 with about 9:1 compression and youll have more than enough power to get yourself in trouble
    also.....do a set of headers youll thank yourself in the long run IMO

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