Which 472/500 engine to use? Need your opinion.
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500, 472, 425, 368 Discussion, Which 472/500 engine to use? Need your opinion. in Cadillac Engine Technical Discussion; I am going to do an engine buildup soon and I own a 70 472 that came out of a ...
  1. #1
    claykuch is offline Cadillac Owners Member
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    Which 472/500 engine to use? Need your opinion.

    I am going to do an engine buildup soon and I own a 70 472 that came out of a Deville. But I can buy a few others cheep. There is a 70ish 500, a 75 500 and a 76 500. I know the 70 472 will make great power but I am worried about using todays gas. As it is unleaded and of a lower octane. Will the 10 to 1 compression of my 472 cause any problems? How about the valves and seats in the older engine that may have been designed for leaded fuel? This won't be a daily driver but will It will be driven regularly on long trips. Maybe I should go with another engine. What do you all think?

    Thanks,
    Clayton

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    davesdeville's Avatar
    davesdeville is offline Banned
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    Re: Which 472/500 engine to use? Need your opinion.

    You'll probably have to use 91 or so with the 70 engines, but in return you get somewhere in the neighborhood of 15hp and 15ft.lbs. over the 75/76 engines that are 8.5:1. I'd get the 70 heads and stick them on a 75/76 engine then run propane but that's just my crazy idea. Do not worry about using lead additive, these engines do not need it as the valve seats are hard enough...

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    The Ape Man's Avatar
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    Re: Which 472/500 engine to use? Need your opinion.

    A gallon of gasoline has about 140% of the BTU of a gallon of propane.
    Propane would only make the engine put out more power if you turned up the atmosphere.

  5. #4
    BluEyes's Avatar
    BluEyes is offline Cadillac Owners Enthusiast
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    Re: Which 472/500 engine to use? Need your opinion.

    I run my '70 472 in 92 octane, no troubles (91 shouldn't be a problem either) I have even advanced the base timing to 10*. I do use some of the lead additive they sell, just for peace of mind, even though others get by without it.
    I'd keep a crank out of one of those 500's for sure though. If you ever want to rebuild your 472, use that crank, and the heads from your '70, and order a rebuild kit for a '70 500ci motor. Then you'll have a 10:1 500.

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    davesdeville's Avatar
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    Re: Which 472/500 engine to use? Need your opinion.

    Quote Originally Posted by The Ape Man
    A gallon of gasoline has about 140% of the BTU of a gallon of propane.
    True but irrelevant... If you stick a propane carb on an engine without any other modification you'll see a drop in power of just a few %. Unless the carb is an intake restriction, then you can see an increase. You can also advance the timing further to get more power out of it. Stick 76cc heads on a 1975 engine like mine for 12.5:1 and you'll be seeing plenty of power... forced induction is another great way to make power seeing how propane has a (R+M)/2 anti-knock rating of 105.

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    The Ape Man's Avatar
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    Re: Which 472/500 engine to use? Need your opinion.

    Quote Originally Posted by davesdeville
    True but irrelevant...
    See you at the finish line kid.

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    davesdeville's Avatar
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    Re: Which 472/500 engine to use? Need your opinion.

    Oh that's mature. You don't know what you're talking about so you spout that off, good work.

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    Aaron J Williams's Avatar
    Aaron J Williams is offline Cadillac Owners Member
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    Re: Which 472/500 engine to use? Need your opinion.

    When I was 17 years old I had a 1970 SDV and thought I was the 500 Cubic Inch King but the more I learn , the more I realize how little I really know.

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    Re: Which 472/500 engine to use? Need your opinion.

    Either way, more performance or slighly less performance, propane is much cheaper than premium pump

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    Re: Which 472/500 engine to use? Need your opinion.

    I'll stick with the proven power of gasoline. Propane is for diesels

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    Re: Which 472/500 engine to use? Need your opinion.

    So Aaron and Ape man, you've done propane conversions before? And with a 70 SDV wouldn't you think you're the 472 king?

    And don't take the 500 king user title too seriously. I just tinker with 'em and read about 'em, but I have way too many irons in the fire to actually know a ton about these engines. But I do know that at $2.70 a gallon for 86 octane, even without mentioning the performance aspect of it, propane is looking better every day.

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    nvrstuk is offline Cadillac Owners Member
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    Re: Which 472/500 engine to use? Need your opinion.

    Well, I'm a newbie to this list and glad to get some solid info on the early Cad's.

    Propane is a GREAT alternative to gas. If you haven't used it you don't know about it's advantages. I rockcrawl and hard core 4 wheel. Propane is great since you can keep running if you are off camber or standing on your tail climbing. Cheap, high octane equivalent and readily available. Major disadvantage is storage systems for your car/truck.

    JMHO

    nvrstuk

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    The Ape Man's Avatar
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    Re: Which 472/500 engine to use? Need your opinion.

    Nobady said that profane was not an alternative to gasoline power.
    Propane was suggested as a performance enhancement here.

    Propane stations suck. I just don't have the time to wait for Mohammed to finish all the gas grille bottles and U-haul business before he can fill my car. My car needs to be able to go through tunnels.
    I need to re-fuel on long trips with the family. Where are all the profane fueling station billboards on route 95?
    All you need is the propane conversion stuff and a new set of heads for high compression to take advantage of the higher octane.
    Don't forget the heavy duty electrical system and starter to start your 12.5:1 4+ inch stroke 8 cylinder engine.
    How much more power are you going to get after spending all this money?
    One advantage might be that you can fart into it when the tank is empty.
    Fill out a balance sheet and submit it to corporate for consideration.

  15. #14
    Colt D is offline Cadillac Owners Member
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    Re: Which 472/500 engine to use? Need your opinion.

    Because this thread on the best 472/500 engine evolved into a thread on alternative fuels, I pose this question to the group:

    Is it possible, and more importantly, feasible, to convert a 10.5:1 472 to natural gas and fill up from home? I hear an option to propane is compressed natural gas (cng), but I'm not sure its compressed coming out of the house. With a long enough hose in the trunk, you could fill up from any of your friends' quick-connect at their BBQ, or with a little more work, the gas dryer. That would be my sportscenter highlight.

  16. #15
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    Re: Which 472/500 engine to use? Need your opinion.

    It is possible, but it is also my understanding that natural gas has crappy mileage. (BTW, im assuming everyone here is going to be making sure they pay the various applicable road taxes for motor vehicle fuel, right? Just think, they caught a few people running thier diesels off home heating oil....)

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