1970 DeVille Convertible.....the adventure begins! - Page 4
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The Classic Cadillac Forum Discussion, 1970 DeVille Convertible.....the adventure begins! in Past Cadillac Vehicle Discussion; Sorry to hear about the compression but you might be right, if it sat that long just driving might free ...
  1. #46
    talismandave's Avatar
    talismandave is offline Cadillac Owners Master
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    Re: 1970 DeVille Convertible.....the adventure begins!

    Sorry to hear about the compression but you might be right, if it sat that long just driving might free it up enough to get by for a while and enjoy it and build up funds.
    That plug is funny man! Clean er up a little and put er back in it'll be good as new!

  2. #47
    smelvis is offline Cadillac Owners Fanatic
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    Oh boy. Ur scaring me "build up funds" so I would assume if it's not a stuck valve I'm in for a project.

    Idk if the plugs are funny but they are something. That's a lot of something for 6 week old plugs in an engine that's ran a few mins here and there. I was thinking I'd ruin the first set anyway.

    I can't drive her around yet. Since my misfires have developed she pretty much stalls right out when I put her in gear and try to move. Got a call out to a more knowledgable person. Hope he can come by.

    Think I'm gonna do the mild flush with sea foam or something. See what happens.

  3. #48
    CADforce69 is offline Cadillac Owners Connoisseur
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    Re: 1970 DeVille Convertible.....the adventure begins!

    double post

  4. #49
    CADforce69 is offline Cadillac Owners Connoisseur
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    Re: 1970 DeVille Convertible.....the adventure begins!

    I think it may probably come from a stuck valve. You can take out valve covers and see with engine running if some valve is not working properly, specially on the cylinders with low compression, then add abundantly some anti-stick product (WD-40, for example) letting it work for one hour and then hit the stuck valves with a rubber hammer. Turn on engine and see if they work; if not, repeat the process. It worked for a friendīs car with stuck valves due to long time sitting. rubber hammer can not damage the valve train.

    Then, you will able to drive your caddy. The most it moves, the best it will run.
    77CDV, 77CDV, talismandave and 1 others like this.

  5. #50
    smelvis is offline Cadillac Owners Fanatic
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    Good advice. I already bought a gasket to pull the cover and see what's moving. I'll probably do that tomorrow.

    What would you recommend for an anti sticking solution?

  6. #51
    smelvis is offline Cadillac Owners Fanatic
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    Disregard that question. Didn't see that you wrote wd-40 when I read it the first time.

  7. #52
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    Re: 1970 DeVille Convertible.....the adventure begins!

    Dude...I didn't realize those were new plugs. I forgot you had already replaced them. I officially retract "funny" and substitute "sad". Hope it all sorts out ok.

  8. #53
    smelvis is offline Cadillac Owners Fanatic
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    Haha thanks retraction accepted. I'm rusty on spark plug 101 what do toasty black crystallized plugs indicate?

  9. #54
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    Re: 1970 DeVille Convertible.....the adventure begins!

    I read this already when I was home for lunch and was hoping by now someone who is more mechanically inclined would have answered you by now. I am a decent parts fitter at best. I appraised used cars for years but we didn't tear them down to do it. Hopefully tomorrow morning some of the smart guys will have answered. It seems some of them check around once a day in the different forums. If not I would start a new thread with the question in the title up on the RWD area. It seems to have more traffic. Best of luck my friend.

  10. #55
    smelvis is offline Cadillac Owners Fanatic
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    sound like we have similar skill sets mechanically. If its completely obvious or I'm told what is wrong I'm not bad at following the manual and doing the work but diagnostics are a challenge at times.

    Everyone here has been a tremendous help and I've also gotten a ton of help from friends locally. I'm very thankful and lucky. Without the feedback and guidance I'd be broke already!

    I'm pretty sure its a carbon foul. Which leads me back to the carb and valves. I have a feeling that the ole quadrajet is in need of desperate attention, a few valves need some help and I also have a sneaky suspicion that the timing chain needs to go.

    I'm hoping that valves are stuck and not severely worn because I do not want to pull the head unless I have to. Pulling the head would probably mean I won't get to cruise until next summer. Im going to pull the covers and see what's up.

    For the carb. The day my misfires appeared the engine was cranked without the distributor hold own tightened. I didn't tell my buddy I had it loose so that's my bad. It backfired something nasty and I swear I saw some smoke come out of the base of the carb. So I plan on replacing that gasket. When I ran it after that I sprayed ether around the base and didn't get any response but I'm gonna do it anyway. Im sure she needs a rebuild but I was hoping to save that for the winter.

    Timing chain doesn't scare me. Changed one on my 73 when I was 17. Took a while but fairly easy to gain access on these big beauties. I'm not even sure it's gone havent done any tests here just seems funny to me.

    I should also mention that even though I put in new points I can't get a reading on my dwell meter but I don't think they are that far off.

    Keep the feedback coming and I'll keep updating.

    I'll see you all on the road someday!
    talismandave and talismandave like this.

  11. #56
    CADforce69 is offline Cadillac Owners Connoisseur
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    Re: 1970 DeVille Convertible.....the adventure begins!

    First of all you must adjust timing. Too much advance helps cold start but makes difficult hot start and makes idle rough. You can try moving the distributor slightly and see how engine runs best but this does not explain greasy plugs or low compression in some cylinders. As to the carb, I think that all plugs would look the same if the problem came from carb. Itīs good cleaning the carb and changing gaskets for a good engine running but I think this is not the main problem.

  12. #57
    smelvis is offline Cadillac Owners Fanatic
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    I have the timing set to 7.5. It seems to like being around 10 but I left it at factory specs for now.

    I haven't checked the plugs on right side yet but the 2&4 plugs looked exactly the same. 6&8 are not firing and i only have low compression in #8 cylinder. Spark is good for both so there has to be a fuel problem and of course a compression problem in #8. The smoke I saw come from base of carb was back left side. Exactly where the manifold feeds 6&8.

    I did squirt oil in all of the cylinders before I started her up the first time. I cranked it a few times w/o plugs to blow any excess oil out. But I would assume some would remain and get on the plugs or just burn off.

  13. #58
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    Re: 1970 DeVille Convertible.....the adventure begins!

    Plugs fouled that bad would suggest a misalligned carb dumping excess fuel into the engine. Also, as you suspect your timing is out of whack.

  14. #59
    smelvis is offline Cadillac Owners Fanatic
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    Well I guess this is why 6&8 are not firing. 1 bent rod and 1 missing rod. I assume that's what a thrown rod is. Shouldn't it have come out somewhere or made a noise or something?

    Time to read up and prepare for some engine work.
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  15. #60
    smelvis is offline Cadillac Owners Fanatic
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    Holy sh@t. It's a wonder she was running at all.

    Could this have been a result of cranking the engine when the hold down wasn't tight or would it take more than that?

    Just wondering if I cause this mess on my own.
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