Keeping a tired 472 happy
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500, 472, 425, 368 Discussion, Keeping a tired 472 happy in Cadillac Engine Technical Discussion; I am back to driving my 70 coupe as a daily driver. I have learned a bit about how to ...
  1. #1
    Nrets is offline Cadillac Owners Member
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    Keeping a tired 472 happy

    I am back to driving my 70 coupe as a daily driver. I have learned a bit about how to keep the thing going, but I have been afraid to do oil changes. I changed the oil a couple thousand miles ago and added until the stick said full. I know the car is supposed to run on 4 quarts, but I added like 8 quarts and it was still low. I recently added another quart and it seems to run quite a bit nicer.
    Are ther 9 quart after market oil pans that I am not aware of for the 472?
    The other thing is that I have been wreaking havoc on the internals of my engine with my cold start routine.
    When it is cold it will not start without starting fluid straight to the carburetor.
    and even then I need to kick it like 4 times before I can get it to hold with my foot halfway to the floor.
    And by hold I mean, it doesn't die as I gradually let off the accelerator for 2 or 3 minutes.
    Then I let it warm up and it starts fine warm.
    Does this sound like a carburetor problem, or a timing problem.
    This engine is bone stock, but it was adjusted out of spec a while ago because at stock specs the thing ran erratically and overheated.
    What can I do short of an engine rebuild to prolong the life of my old beater?

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  3. #2
    Brother_B's Avatar
    Brother_B is offline Cadillac Owners Fanatic
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    Re: Keeping a tired 472 happy

    Someone on here not too long ago was worried that his dipstick was too short because he had to put in 5 quarts wtihout replacing the oil filter at an oil change. He was asking what the length should be and here is what I wrote:

    "The dipstick in my 472 measures 20.50" overall length, measured from the point where it bottoms out on the tube. It's 18.75" to the 'add one qt' mark and 17.94" to the 'Full' mark."

    Then again, I'm not sure if _mine_ is the correct length. But you may want to check it. If you're not leaking, the pan must be deeper, right? Don't quote me on that.

    You say the engine is bone stock but it was adjusted out of spec. What was adjusted? Was the timing advanced to cool it down? Was vacuum advance switched to manifold vacuum instead of ported carburetor vacuum? Or are you utilizing the ported vacuum switch that is intended to deal with overheating at idle? The ported vacuum switch on my 69 was not connected when I got mine. I now know that it is a miracle that the thing ran as well as it did. I would bet a lot of mechanics would not know how to hook that thing back up properly. I think difficult starting can be caused by having your initial timing too far advanced.

    Anyway, I think you should get the car tuned up, and specifically state that you want the timing and carburetor addressed. ANd get it done somewhere that knows older carbureted cars. I would be very concerned about the 9 quarts of oil, and make sure you get to the bottom of that mystery.

  4. #3
    Nrets is offline Cadillac Owners Member
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    Re: Keeping a tired 472 happy

    The timing is advanced. Quite a bit. The car runs really poorly without the timing advanced. I remember a mechanic set it to stock and it overheated. He advanced it a bit and took the line off the vacuum advance and stuck a broken fuse into it. I'm still not sure why he did that, but I didn't question it because it ran pretty well. The engine actually isn't totally stock...I put an HEI distributor in...so there is no more vacuum advance. Are you saying it would start easier without the timing advanced? It runs awful without the timing advanced.

  5. #4
    BluEyes's Avatar
    BluEyes is offline Cadillac Owners Enthusiast
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    Re: Keeping a tired 472 happy

    Fix the vacuum advance. It makes up for lower cylinder pressures at part throttle by advancing the timing further. Makes the car run smoother and improves part throttle power/fuel economy (where you spend most of your time!) As you open the throttle, the vacuum cannister provides less and less advance to match the changing conditions.

    The advanced timing might be to make up for the lack of vacuum advance but it's not good for the motor because it will be over-advanced at WOT which will do far worse things to the internals than your cold starts ever will in 1,000,000 miles. That is assuming that the timing is correct. Don't go back to the mechanic who stuck a broken fuse in the vacuum line. There are so many reasons why that is the wrong thing to do unless it was a temporary fix untill you got a new vacuum advance cannister. (It wouldn't surprise me if the cannister has a ruptured diaphragm)
    You need to find a good mechanic or learn to do your own work. Get a new vacuum cannister for a Caddy in the first year or two that they ran HEI (the '70 cannister will not work on HEI). Verify that the timing marks are correct and set the timing to between 7.5*-10*. 7.5* is stock, but my 472 doesn't mind 10*.
    Oh, and in setting the timing, remember that #1 is the passengers front cylinder. Many other GM's put #1 at the drivers front and if you take timing off the wrong cylinder it will throw the readings down the tubes.

    The starting problem sounds exactly like a broken/misadjusted choke. The choke provides a richer mixture at start (why you need starter fluid and alot of pumping) and holds the idle up while the engine is cold (why you need to use your foot). Once the choke is working, you can honestly just start the car and drive away. It's better for the car that way anyways.

  6. #5
    cadillacmike68's Avatar
    cadillacmike68 is offline Cadillac Owners Connoisseur
    Automobile(s): 68 DVC, 96 FLTWD Brg, 09 STS N* Platinum, 11 CTS Premium
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    Re: Keeping a tired 472 happy

    Hey BrotherB
    Is the ported switch that little wax bulb three nipple thing that is screwed into the front of the block / head?? Mine was disconnected when I bought it in 1998, but it was tested good and re-hooked up during the rebuild. There were so many little things disconnected or wrong in my car before the rebuild that I'm amazed that it ran at all for those years!!! I agre that it is important to keep everything functional because the little things tend to have a cascading effect on performance and engine life as well!

  7. #6
    Brother_B's Avatar
    Brother_B is offline Cadillac Owners Fanatic
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    Re: Keeping a tired 472 happy

    Yes, the ported vaccum switch is the thing sticking out the front of the block. It has the wax bulb inside that expands when it gets hot, actuating the switch to change the vacuum advance from ported to full manifold. I think it operates the idle speed-up when the A/C is on too. Your '68 looks great, by the way. Hope you get a lot more time to enjoy it.

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