Question about modifying a 472 in '70 convertible that is in good original shape
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The Classic Cadillac Forum Discussion, Question about modifying a 472 in '70 convertible that is in good original shape in Past Cadillac Vehicle Discussion; Wanting to rebuild the engine in my newly acquired '70 convertible. At this point, I'm just gathering information. The car ...
  1. #1
    chrisntam is offline Cadillac Owners Fanatic
    Automobile(s): 1970 Deville Convertible
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    Question about modifying a 472 in '70 convertible that is in good original shape

    Wanting to rebuild the engine in my newly acquired '70 convertible. At this point, I'm just gathering information. The car is in really good shape except for the engine. I'm yet to do a compression test and put a gauge on the oil pressure, but at this point I'm going through the MTS catalog and want one of everything. How acceptable is it to make the 472 into a 500 in a DeVille? What about matching numbers? Does it de-value the car if not the original block and heads? Or is that just a muscle car thing? Aluminum heads and intake/aftermarket carb on cruiser like this a good idea? As silly as it sounds, I want to put forged rods/pistons in along with a #10 MTS cam, ported heads, roller rockers, but want to retain the original carb, air cleaner and intake/exhaust manifolds. I just like the look of the engine as it is now. I'm a slow mover, but like to gather as much info as I can so when I decide how I want to proceed, I can and will be comfortable with the decisions I've made. I know it's my car and I can do what I want with it, but I was wanting some input for those who have been there, done that.

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    77CDV's Avatar
    77CDV is offline Cadillac Owners Master
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    Re: Question about modifying a 472 in '70 convertible that is in good original shape

    Unless you're going for concours quality, matching numbers isn't a big thing with Cadillacs. The modifications you propose are fairly moderate and will not affect the car's value as a fun cruiser and driver. The only impact will be for those looking for an original, correct car.

  4. #3
    70eldo's Avatar
    70eldo is offline Cadillac Owners Connoisseur
    Automobile(s): 1970 Eldorado.
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    Re: Question about modifying a 472 in '70 convertible that is in good original shape

    Check out cad500parts.com. They have everything you need to overhaul or convert your 472. Also info to your questions.

  5. #4
    disturbio's Avatar
    disturbio is offline Cadillac Owners Fanatic
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    Re: Question about modifying a 472 in '70 convertible that is in good original shape

    cadillacowners is a good forum too
    77CDV likes this.

  6. #5
    FoxRodder's Avatar
    FoxRodder is offline Cadillac Owners Fanatic
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    Re: Question about modifying a 472 in '70 convertible that is in good original shape

    Typical modification is the edelbrock aluminum intake manifold which will accept your original carb if you want. The factory intake is cast iron so along with better breathing, and shiny metal there is a weight reduction. I would like to put one on mine but money is tight and I have fairy tale daydreams of a late model 5.3/6.0 swap which may or may not ever happen. I think the factory exhaust manifolds are prone to cracking and leaking and rotted hardware. Sanderson I think is the best rated headers for these engines and definitely preferable to factory manifolds.

    The weak link in these engines that I have read is mainly the wimpy valvetrain that cannot stand up to rpms and high lift cams. The rockers are not very good past stock from what I understand and the springs need help. MTS has all the answers to the valvetrain stuff and pretty much everything else.

    They also came with the lovely nylon coated timing gears that come apart and cause problems. Make sure that is corrected.

    Consider an electronic ignition conversion under your stock cap, or an HEI conversion if its not already.

    This stuff adds up to a lot of money very quick.

  7. #6
    chrisntam is offline Cadillac Owners Fanatic
    Automobile(s): 1970 Deville Convertible
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    Re: Question about modifying a 472 in '70 convertible that is in good original shape

    I agree about the money adding up. Wanting to do it once, but do it right. I like the look of the factory engine/air cleaner set up and the way the compressor sits atop the motor. MTS tells me they have a ported factory intake that flows nearly as well as the edelbrock. That's what they say. Anyone have any experience with it?

    Did have a chance (finally) to do some general tests on the engine. I found the engine serial number and fortunately it matches the VIN number on the car! Vacuum level is good, about 22 inches, but the needle is not steady. It bounces pretty good but only within about a half inch of vacuum. Did a compression test, one cylinder is 137, one is 145, three are 150, two are 155 and one is 160. Oil pressure is 30 to 35 warmed up and at idle. I also found the primary throttle shaft on the factory quadrajet has a bunch of slop it.

    So it appears the bottom end is good (or as good as can be expected for a 43 year old engine), but either the lifter(s) or the rocker arms are clattering quite a bit. Before I bought it, it only had 10 miles put on it in 12 years (or so the repair documentation says). I'll do further investigation on the clattering as time permits. I'll also check the cam timing gear too. Maybe, it just needs a set of ported MTS heads, ported factory intake, a carb rebuild, an MTS #10 cam, new lifters, a street roller timing set and shaft rocker assemblies. I think after all that, I'll be good to go!

    Will let you know how it goes.............

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