1969 472 help I'm stumped !!!!!
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The Classic Cadillac Forum Discussion, 1969 472 help I'm stumped !!!!! in Past Cadillac Vehicle Discussion; so i just bought a 69 sdv. its all original as far as i can tell with 66k miles. it ...
  1. #1
    superjeep is offline Cadillac Owners Member
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    1969 472 help I'm stumped !!!!!

    so i just bought a 69 sdv. its all original as far as i can tell with 66k miles. it didnt run and had been sitting for a few years before i got it. anyway i got it home put a new battery,changed fluids and fired it up. she started and ran. once it warmed up it off fast idle when i would goose it and give a good rev up it would ping like crazy.
    i assumed the gas was bad so i drained the tank filled with fresh 93 and let it run. i took it for a ride and it ran ok. as soon as i would give it any kind of moderate throttle it pinged so bad it sounded like a bag of bolts in the motor. i brought it home and checked the timing. it was at 25 degrees advanced!!!!! well there i think is my issue.
    after spending all day freeing up the frozen dist i get out the dwell meter and timing light,unplug the vac advance and go to time it. when i put it at 5 degrees like it should be at it barley ran popped out the carb and had zero power. it wouldn't even idle on its own.

    so i pull the dist look at the timing chain see the nylon was not there anymore and figured it jumped a tooth.

    i have some new timing sets for the 472 in my garage as i have a few caddys and always seem to be getting more haha. i pull the front cover and to my amazement the timing marks are still lined up!!

    i put the new gears and chain in anyway put it all back together and still have the same issue!!!!!

    pulled the valve covers and all the rockers seem to be making full movements so I'm guessing i can rule out a worn lobe.

    i put the timing back to 20 degrees and it runs and drives with a slight miss at idle but smooth at light throttle just pings like crazy.

    im stumped here can anyone please help? thanks you

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    Jeff R's Avatar
    Jeff R is offline Cadillac Owners Fanatic
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    Re: 1969 472 help I'm stumped !!!!!

    Well, you've done just about everything. I have a 70 and plan to change the timing chain because of all that I have read here.
    We know the timing is good when you check it. If I remember correctly there is a vac timing advance that is supposed to kick in if the engine gets hot. Next time you go for a drive it mite be worth disconnecting it to be sure that temp switch isn't bad and changing the timing on you. Do you think you may have an issue with the advance weights? Maybe it is advancing too far when it gets to a certain rpm.
    Changing from the ignition system, how is the carb? Does it get really good (for a 68) mileage? Perhaps it is running very lean and that is causing the ping.
    Let us know what you find on this.
    Jeff

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    CADforce69 is offline Cadillac Owners Connoisseur
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    Re: 1969 472 help I'm stumped !!!!!

    My '69 timing had to be too advanced due to a bad advance weights/springs. It started well when cold but when engine was at operating temperature and you turned it off and tried to start it again it was difficult for the engine. I changed the distributor and this problem solved; in addition the car run much better. Have you any compatible distributor (for a 472-500 engine) you can swap so at least you can discard a bad distributor? Anyway, you can find dists for a good price at rockauto.com.

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    superjeep is offline Cadillac Owners Member
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    Re: 1969 472 help I'm stumped !!!!!

    Yeah i have another dist.....its not the pinging that confuses me i know that is from the advanced timing.....its when it is at 5 degrees btdc that it runs like it is retarded 15 degrees btdc

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    superjeep is offline Cadillac Owners Member
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    Re: 1969 472 help I'm stumped !!!!!

    ok i played with it a bit today. tried new points and condenser,new cap and rotor with no change. while it was running i pulled plug wires off. i found that #2,8,3,and 5 had little to no change on how it ran pulling them off. i pulled #2 and it was wet with fuel and it is getting a spark. at this point I'm thinking compression. my tester is broken but i started it with the plug out and it blasted the posters off the wall! i know i need to test it to get a number......but i just don't get this!

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    sawyer is offline Cadillac Owners Member
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    Have you checked that the plug wires are on right?

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    superjeep is offline Cadillac Owners Member
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    Re: 1969 472 help I'm stumped !!!!!

    Yeah like 4 times hahaha

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    Re: 1969 472 help I'm stumped !!!!!

    Do you think you have a intake manifold gasket issue? If it is sucking air it will run very lean and ping. A bad gap and it would be too lean to fire which would cause the wet plug you were talking about.
    Jeff

  10. #9
    superjeep is offline Cadillac Owners Member
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    Re: 1969 472 help I'm stumped !!!!!

    Thats what im thinking jeff. I was hoping to get some insight before i go ripping it all apart

    ----------

    The top looks sealed it has the years of dust and dirt on it. It could be leaking from the bottom side.....but wouldnt it suck and burn oil if so?

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    superjeep is offline Cadillac Owners Member
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    Re: 1969 472 help I'm stumped !!!!!

    Ok i pulled the intake.....gasket is fine.....what the hell!!

  12. #11
    Jeff R's Avatar
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    Re: 1969 472 help I'm stumped !!!!!

    Now wait--- You posted that you were thinking it may be the gasket at 10:42 and at 12:20 you were done?? Jeez, I want to be that fast. It would take me that long just to read the manual.
    Need to figure out why you have dead cylinders causing the wet plugs. I think you found the ones that may not be firing well when you disconnected the plug wires.

    Next perhaps be a compression check. Not the kind that seems to be done on cars, but the kind we do on the airplane which would check the valves. Get the cylinder, any cylinder that you are checking on up to TDC on the compression stroke then blow some shop air in there. Just stick a piece of rubber fuel line on the end of the air nozzle and stick it in the spark plug hole. If you hear air leaking back thru the carb then you have an intake valve leak, out the exhaust then an exhaust leak and if it comes out the case vent then it is past the rings----Keep your hands away from the fan because too much air pressure in a good cylinder will blow the piston down and spin the engine.
    Also wondering if you have a sticking valve issue. When cold all is fine but when it is hot and everything expands then it could slow the valve down. It may be fine at idle speeds but just not able to keep up at hi RPMs.

  13. #12
    superjeep is offline Cadillac Owners Member
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    Re: 1969 472 help I'm stumped !!!!!

    It actually only took me 28 mins to pull the intake. My girlfriend said i have to be ready to leave in 45 mins...i pulled it, got pissed when the gasket was fine,swore,threw some stuff then went in and cleaned up hahaha.

    Ill do a comp check and leakdown tomorrow and post back with results. Thanks for the help
    70eldo likes this.

  14. #13
    carnut is offline Cadillac Owners Master
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    Re: 1969 472 help I'm stumped !!!!!

    Could the distributor advance weights be stuck fully extended? With the rotor off, can you see the springs and weights move freely?
    CADforce69 likes this.

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    Jeff R's Avatar
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    Re: 1969 472 help I'm stumped !!!!!

    That's what I thought too but he said the weights were OK. I'm thinking it would have to be somethng else as he has cylinders that are dead. I really thought it was the intake gasket or that it is sucking air somehow. Guess I was wrong.

    28 Minutes to pull it. Pretty darn good. As I said, I would still be reading the manual after only 28 minutes. Good Job!!
    Jeff

  16. #15
    sawyer is offline Cadillac Owners Member
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    Try putting some marvel mystery oil in the gas and put plenty if it in there and run it you may have a valve or two that's gummed up in the guide and half way working. I had this happen to me and that cured it. You can hold the throttle open some and pour some straight in the carb to just be ready for lots of smoke

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