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Burning Oil conundrum

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  • Nick D.
    Expired
    • December 15, 2020
    • 94

    Burning Oil conundrum

    Aloha!
    The original owner of my '64 replaced the original 327/300 with a '70 Chevelle 350. The engine burned a quart of oil every 500 miles or so when I first drove it from Houston to Long Beach but I never saw smoke. I replaced the carburator with one too big which fouled the plugs (fast) so I thought it was valve guide seals. Did a valve job and the guy said the carb was too big and that it didn't need a valve job. Good, no more fouled plugs but what was minor smoke got worse.

    Once at operating temp, after idling or low rpm driving, upon accellation I get a cloud. Bad but not horibble disaster type, But then it mostly goes away. Mostly. I punch it and yes there is some blue smoke but not a lot and its not continuous.

    Problem is mostly on passenger side but still, both sides. Compression psi when I tested it upon arrival here, just to know what it was, readings are, from 1-8 are 145, 155, 145, 155,155, 150, 155, 175. It made lifter noise on the passenger side after the valve job (not prior) but not bad and not continuous. Mehanic says that causes the smoke... only...its one lifter on one side.

    Do those compression numbers sound like rings? The scenario is confusing. I don't know what else it could be. I'd appreciate input. Check my pics. When I bought the car, the engine was so clean you could eat off it. Based on what I know, the second owner would not have found a worn engine acceptable.
  • Mike E.
    Extremely Frequent Poster
    • February 28, 1975
    • 5138

    #2
    Re: Burning Oil conundrum

    Nick, no pics to check.

    Comment

    • Duke W.
      Beyond Control Poster
      • January 1, 1993
      • 15671

      #3
      Re: Burning Oil conundrum

      I can't make much sense out of your post. What work was actually done. Please be specific.

      The compression numbers aren't great, but don't justify an overhaul unless you're a perfectionist.

      I assume the "'70 350" from the Chevelle is a 350/300, which is basically a stroked version of your 327/350 with A Q-jet carb instead of AFB. Both were OE with very similar cams that should idle at 18" @ 500, if the engine has different idle behavior what is it, xx" Hg @ yyy RPM, and tell us the details of the carburetor changes.

      Check that the PCV system is correctly configured with a properly functioning valve.

      Duke

      Comment

      • Owen L.
        Very Frequent User
        • September 30, 1991
        • 868

        #4
        Re: Burning Oil conundrum

        What do your spark plugs look like?
        I'm a little confused about the valve job - it got one but didn't need it? If it had one, did they undergo complete rebuilds with new guides, seat cutting, new valves, new seals, etc.?
        That one cylinder at 175 compared to the rest kinda leads me to believe it has the oil leak and the excess oil is helping to seal the rings. I think your next step is to do a leak-down test on each cylinder.

        It may be just me and the way I'm reading into your message, but I'm not very confident with your mechanic/valve guy... A mismatched carb shouldn't have anything to do with oil burning.

        Comment

        • Joe L.
          Beyond Control Poster
          • February 1, 1988
          • 43221

          #5
          Re: Burning Oil conundrum

          Originally posted by Nick Drance (67554)
          Aloha!
          The original owner of my '64 replaced the original 327/300 with a '70 Chevelle 350. The engine burned a quart of oil every 500 miles or so when I first drove it from Houston to Long Beach but I never saw smoke. I replaced the carburator with one too big which fouled the plugs (fast) so I thought it was valve guide seals. Did a valve job and the guy said the carb was too big and that it didn't need a valve job. Good, no more fouled plugs but what was minor smoke got worse.

          Once at operating temp, after idling or low rpm driving, upon accellation I get a cloud. Bad but not horibble disaster type, But then it mostly goes away. Mostly. I punch it and yes there is some blue smoke but not a lot and its not continuous.

          Problem is mostly on passenger side but still, both sides. Compression psi when I tested it upon arrival here, just to know what it was, readings are, from 1-8 are 145, 155, 145, 155,155, 150, 155, 175. It made lifter noise on the passenger side after the valve job (not prior) but not bad and not continuous. Mehanic says that causes the smoke... only...its one lifter on one side.

          Do those compression numbers sound like rings? The scenario is confusing. I don't know what else it could be. I'd appreciate input. Check my pics. When I bought the car, the engine was so clean you could eat off it. Based on what I know, the second owner would not have found a worn engine acceptable.
          Nick-------

          Remove the intake manifold and check the intake ports in the heads. Check to see if the ports are wet with oil, mostly on the bottom half of the ports. If so, you have a problem with sealing of the manifold to the heads causing oil to be drawn out of the lifter valley and into the ports. This is a VERY common problem with small block engines. How to solve it? I wish I knew. I can tell you that no intake manifold gasket or sealant will solve it.
          In Appreciation of John Hinckley

          Comment

          • Nick D.
            Expired
            • December 15, 2020
            • 94

            #6

            Comment

            • Nick D.
              Expired
              • December 15, 2020
              • 94

              #7

              Comment

              • Nick D.
                Expired
                • December 15, 2020
                • 94

                #8
                Re: Burning Oil conundrum

                You’re right about not trusting my mechanic, and I say told you the reasons why you’d understand. The son inherited the shop from his dad and I’ve been going there for years. I like them but things aren’t what they should be. It’s not easy find a good mechanic here on the island. yes you’re right about the compression test done properly. That shouldn’t be too difficult if they don’t leave it in gear like the last time… The father said the 175 was caused by a stuck oil ring, which I never heard of but maybe your explanation is more believable. The big problem is coming on the passenger side but they both have that problem. As I say, the odd thing is that when I drove the car from Houston to California after first buying it, I didn’t see any oil smoke, but along the way, I was shocked at how much oil it was burning , which didn’t make any sense to me.
                Last edited by Nick D.; March 30, 2023, 01:09 PM. Reason: TMI

                Comment

                • Nick D.
                  Expired
                  • December 15, 2020
                  • 94

                  #9
                  Re: Burning Oil conundrum

                  Thanks Duke. The problem is hard to make sense of because the carburator thing go involved. I'm sorry I let any of these guys touch it. The idle is so smooth, If I recall, around 700-800 rpm or so, I get a beautiful, deep hum. Acording to the serial numbers, the engine is a 350, stamped at the plant that made Chevelles and Monte Carlos. It's specifically indicated for a 4spd, 4bbl. Aside from the Edlebrock intake and 540 carb that was on the car when I got it, I doubt the engine was further modified.

                  As for the valve job..the guy said it didn't need it and the carb was too big and he was right. He grinded seats and valves, new seals.

                  PCV valve was replaced.

                  Originally posted by Duke Williams (22045)
                  I can't make much sense out of your post. What work was actually done. Please be specific.

                  The compression numbers aren't great, but don't justify an overhaul unless you're a perfectionist.

                  I assume the "'70 350" from the Chevelle is a 350/300, which is basically a stroked version of your 327/350 with A Q-jet carb instead of AFB. Both were OE with very similar cams that should idle at 18" @ 500, if the engine has different idle behavior what is it, xx" Hg @ yyy RPM, and tell us the details of the carburetor changes.

                  Check that the PCV system is correctly configured with a properly functioning valve.

                  Duke

                  Comment

                  • Nick D.
                    Expired
                    • December 15, 2020
                    • 94

                    #10
                    Re: Burning Oil conundrum

                    I meant profle pics. There is one of the engine. Clean as a whistle.

                    Comment

                    • Nick D.
                      Expired
                      • December 15, 2020
                      • 94

                      #11
                      Re: Burning Oil conundrum

                      Owen, The carb was too big and fouiled the plugs. It was a new carb. I thought the fouled plugs was an oil problem. I didn't look at them, mechanic didn't object, my bad). It's the head guy that said the foulded plugs and running rought was the carb. He was right. Replaced with 600 dfm, engine ran well, then got oil smoke.

                      We don't have super highways here on Maui, no racing. The carb expert in Honolulu put on a 750. I should have doubted him and asked about the size. Apparently he thought this nice #3 Stingray was giong to live at the track..which we don't have on this island. Yes, mechanic is a challenge... they are not easy to find here.. he's not incompetent but blind faith is not appropriate with him.

                      The oil smoke problem arose after the valve job. Still, the engine runs great. From what I read here, the problem is under the intake. Oil is getting where it doesn't belong. Mechanic says its a stuck lifter (new problem after the valve job) Sounds like just one, not a consistent tap.

                      Comment

                      • Nick D.
                        Expired
                        • December 15, 2020
                        • 94

                        #12
                        Re: Burning Oil conundrum

                        I think you're right. The only thing is, if it was not a problem before the valve job, it shouldn't be after..unless there is a way to create a mismatch in the process or re-assembly. I'll take a ride up to the Head guy, see what he says, say hello, and thanks for diagnosing the too big carb problem which fixed the fouled plugs, running rough problem . Mostly. I think my plugs are fouled enough again that it no longer hums at idle, but not far off..it was perfect, smooth, steady rpm recently however. Some 3500 rpm between shifts might help that a little.

                        Guys, I apologize for being unclear. There’s a little or no oil smoke when I start up the car after it’s been sitting for a couple weeks.

                        You've given me anough to go on I think. I need a wet compression test and see if there is a way to diagnose a problem that might be caused by something not lining up between the intake and heads. Thanks for your help!
                        Last edited by Nick D.; March 30, 2023, 05:43 PM.

                        Comment

                        • Rich G.
                          Extremely Frequent Poster
                          • August 31, 2002
                          • 1397

                          #13
                          Re: Burning Oil conundrum

                          What Joe Lucia said!
                          1966 L79 Convertible. Milano Maroon
                          1968 L71 Coupe. Rally Red (Sold 6/21)
                          1963 Corvair Monza Convertible

                          Comment

                          • Ralph E.
                            Expired
                            • February 1, 2002
                            • 905

                            #14
                            Re: Burning Oil conundrum

                            Nick,
                            Many years ago on this forum another Corvette owner had a similar problem. If you go back in the archives you may find it.
                            It was the intake manifold as Joe Lucia stated.
                            Not sure how it was corrected.

                            Comment

                            • Rich G.
                              Extremely Frequent Poster
                              • August 31, 2002
                              • 1397

                              #15
                              1966 L79 Convertible. Milano Maroon
                              1968 L71 Coupe. Rally Red (Sold 6/21)
                              1963 Corvair Monza Convertible

                              Comment

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