69 L-68, oil puddle in the intake. - NCRS Discussion Boards

69 L-68, oil puddle in the intake.

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Douglas C.
    Very Frequent User
    • August 31, 1990
    • 384

    69 L-68, oil puddle in the intake.

    Hi all. Been trying to find out why my 69 L-68 is running poorly, ignition all good I think, although I wonder if my distributor is worn, I get a slight scraping noise from the distributor cap at times. Erattic idle, off idle stumble. But:

    Thinking the previous owner may have put the center carb manifold gasket upside down exposing the PCV and maybe causing a vaccum leak I pulled the center, and other two carbs.

    Carb gaskets were on correctly, but I look down the intake holes and in the front runners mostly and some in the rear runners I have a small puddle of oil. PCV / hose does not have excessive oil and PCV runner in center of intake is a little moist, but does not look like it is sucking raw oil. When running there is no sign of burning oil. I pulled the center 4 intake bolts but no sign of oil on the threads.

    Now, I just bought the car from a previous owner, and the owner prior to him did the engine rebuild. Stock except for a Comp Cam 280 Magnum. Car has been lying in a garage for a few years with minimal use.

    Since that cam has specs close to a stock L-71 I put in a CV 941 PCV as called for for a L-71. Idle manifold vacuum in the 12" to 13" range. Now, I do recall after speaking to the guy who rebuilt the engine that he had the heads milled somewhat. Block not decked as the matching # pad is untouched.

    So, any thoughts where the oil is coming from? I'm thinking if the heads were milled maybe the intake to head ports are off slightly and allowing oil in the intake. I have not run the car much other than idling, so maybe the high manifold vacuum has worked at pulling in more oil than normal driving.

    Thanks. Doug
  • Douglas C.
    Very Frequent User
    • August 31, 1990
    • 384

    #2
    Re: 69 L-68, oil puddle in the intake.

    Originally posted by Douglas Craner (18086)
    Hi all. Been trying to find out why my 69 L-68 is running poorly, ignition all good I think, although I wonder if my distributor is worn, I get a slight scraping noise from the distributor cap at times. Erattic idle, off idle stumble. But:

    Thinking the previous owner may have put the center carb manifold gasket upside down exposing the PCV and maybe causing a vaccum leak I pulled the center, and other two carbs.

    Carb gaskets were on correctly, but I look down the intake holes and in the front runners mostly and some in the rear runners I have a small puddle of oil. PCV / hose does not have excessive oil and PCV runner in center of intake is a little moist, but does not look like it is sucking raw oil. When running there is no sign of burning oil. I pulled the center 4 intake bolts but no sign of oil on the threads.

    Now, I just bought the car from a previous owner, and the owner prior to him did the engine rebuild. Stock except for a Comp Cam 280 Magnum. Car has been lying in a garage for a few years with minimal use.

    Since that cam has specs close to a stock L-71 I put in a CV 746 PCV as called for for a L-71. Idle manifold vacuum in the 12" to 13" range. Now, I do recall after speaking to the guy who rebuilt the engine that he had the heads milled somewhat. Block not decked as the matching # pad is untouched.

    So, any thoughts where the oil is coming from? I'm thinking if the heads were milled maybe the intake to head ports are off slightly and allowing oil in the intake. I have not run the car much other than idling, so maybe the high manifold vacuum has worked at pulling in more oil than normal driving.

    Thanks. Doug
    Whoops, corrected to read PCV # CV 746.

    Comment

    • William C.
      NCRS Past President
      • May 31, 1975
      • 6037

      #3
      Re: 69 L-68, oil puddle in the intake.

      Define "small Puddle" A drop or two could come down the pcv hose during cooldown.
      Bill Clupper #618

      Comment

      • Douglas C.
        Very Frequent User
        • August 31, 1990
        • 384

        #4
        Re: 69 L-68, oil puddle in the intake.

        Originally posted by William Clupper (618)
        Define "small Puddle" A drop or two could come down the pcv hose during cooldown.
        The front lower runner has a puddle about the size of table spoon full. The other front runner and rear runners less. The valve cover opening for the PCV has a tiny puddle on top of the baffle. These are aftermarket valve covers.

        Comment

        • Joe L.
          Beyond Control Poster
          • February 1, 1988
          • 43220

          #5
          Re: 69 L-68, oil puddle in the intake.

          Originally posted by Douglas Craner (18086)
          Hi all. Been trying to find out why my 69 L-68 is running poorly, ignition all good I think, although I wonder if my distributor is worn, I get a slight scraping noise from the distributor cap at times. Erattic idle, off idle stumble. But:

          Thinking the previous owner may have put the center carb manifold gasket upside down exposing the PCV and maybe causing a vaccum leak I pulled the center, and other two carbs.

          Carb gaskets were on correctly, but I look down the intake holes and in the front runners mostly and some in the rear runners I have a small puddle of oil. PCV / hose does not have excessive oil and PCV runner in center of intake is a little moist, but does not look like it is sucking raw oil. When running there is no sign of burning oil. I pulled the center 4 intake bolts but no sign of oil on the threads.

          Now, I just bought the car from a previous owner, and the owner prior to him did the engine rebuild. Stock except for a Comp Cam 280 Magnum. Car has been lying in a garage for a few years with minimal use.

          Since that cam has specs close to a stock L-71 I put in a CV 941 PCV as called for for a L-71. Idle manifold vacuum in the 12" to 13" range. Now, I do recall after speaking to the guy who rebuilt the engine that he had the heads milled somewhat. Block not decked as the matching # pad is untouched.

          So, any thoughts where the oil is coming from? I'm thinking if the heads were milled maybe the intake to head ports are off slightly and allowing oil in the intake. I have not run the car much other than idling, so maybe the high manifold vacuum has worked at pulling in more oil than normal driving.

          Thanks. Doug
          Doug-----


          Have you run the engine enough to know what the oil consumption is like (i.e. miles per quart)?
          In Appreciation of John Hinckley

          Comment

          • Douglas C.
            Very Frequent User
            • August 31, 1990
            • 384

            #6
            Re: 69 L-68, oil puddle in the intake.

            Originally posted by Joe Lucia (12484)
            Doug-----


            Have you run the engine enough to know what the oil consumption is like (i.e. miles per quart)?
            No Joe, been having stumble issue, thought maybe previous owner maybe had center carb manifold gasket upside down, exposing PCV slot causing vacuum leak, but after pulling carbs I find what seems like excessive oil in the runners. I have had it idling quite a bit during this stumble issue. Now, I'm using PCV CV746 thinking that is correct, but wonder now if CV 736 is correct. My L-68 is stock except for a Comp Cam Magnum 280. There are no signs of oil smoking at all.

            Thanks,

            Doug

            Comment

            • Grahame M.
              Very Frequent User
              • November 7, 2011
              • 225

              #7
              Re: 69 L-68, oil puddle in the intake.

              Hi Doug,

              I have the same model and when i removed the carbs to have them refurbished i noticed the same oil puddle. I'm not sure of the cause either but i have the correct PCV valve but replaced alloy rocker covers with repro chrome and correct fittings (not cheap). I'll give it a good run and recheck but could it be the carb wasn't working correctly?? I don't know.

              A friend of mine that has built BB's for a while now suggested that it could be pulling in from PCV. I'd like to know if something is wrong if this is a symptom.

              Unlike yours my engine was running very smoothly prior to carb rebuild and now runs even better. Good steady vacuum suggests engine is reasonably healthy for its age, a bit like me.

              Cheers

              Grahame
              69 427 Tri-Power 4 Speed
              Black on Black

              Comment

              • Timothy B.
                Extremely Frequent Poster
                • April 30, 1983
                • 5186

                #8
                Re: 69 L-68, oil puddle in the intake.

                Douglas,

                If you are dealing with a stumbling issue at no load conditions like free reving from idle that engine will not drive very well. You may give some thought to removing the two outer carburetors, blocking the intake with a gasket and plate and tuning the center carburetor.

                After you get that sorted out, install the two outside carburetors and tune the secondary's.

                Comment

                • Douglas C.
                  Very Frequent User
                  • August 31, 1990
                  • 384

                  #9
                  Re: 69 L-68, oil puddle in the intake.

                  Originally posted by Timothy Barbieri (6542)
                  Douglas,

                  If you are dealing with a stumbling issue at no load conditions like free reving from idle that engine will not drive very well. You may give some thought to removing the two outer carburetors, blocking the intake with a gasket and plate and tuning the center carburetor.

                  After you get that sorted out, install the two outside carburetors and tune the secondary's.
                  Well, I had the linkage adjusted correctly, throttle plates closed front & rear carbs at idle, if I put my hand over the front & rear carbs no change in idle. Plus, I capped off the rear T fitting on the manifold so no vacuum to headlights, wiper door, etc. Still erratic stumble. So I already now have all carbs pulled off.

                  I wonder if the CV746 PCV I was using is that much different than a correct CV736. But, I think for now I should pull the intake and see if there are signs of vacuum leak, oil on intake gasket bottoms, maybe mating surface to heads not spot on. Previous owner did mill the heads so could be not matching up right to the stock intake.

                  Ignition seems o/k, car runs very cool for a big block, about 190 degrees, does not smoke oil. So, I'm down to intake / carbs / vacuum.

                  Any other thoughts appreciated.

                  Thanks, Doug

                  Comment

                  • Duke W.
                    Beyond Control Poster
                    • January 1, 1993
                    • 15670

                    #10
                    Re: 69 L-68, oil puddle in the intake.

                    Originally posted by Douglas Craner (18086)
                    I have not run the car much other than idling, so maybe the high manifold vacuum has worked at pulling in more oil than normal driving.

                    Thanks. Doug
                    It may not be oil - but condensed high boiling point components of the gasoline. Is the heat riser passage blocked? You need to go out and get the engine up to operating temperature for at least 30 minutes. The check again for the puddle.

                    Duke

                    Comment

                    • Terry M.
                      Beyond Control Poster
                      • September 30, 1980
                      • 15599

                      #11
                      Re: 69 L-68, oil puddle in the intake.

                      Originally posted by Douglas Craner (18086)
                      Well, I had the linkage adjusted correctly, throttle plates closed front & rear carbs at idle, if I put my hand over the front & rear carbs no change in idle. Plus, I capped off the rear T fitting on the manifold so no vacuum to headlights, wiper door, etc. Still erratic stumble. So I already now have all carbs pulled off.

                      I wonder if the CV746 PCV I was using is that much different than a correct CV736. But, I think for now I should pull the intake and see if there are signs of vacuum leak, oil on intake gasket bottoms, maybe mating surface to heads not spot on. Previous owner did mill the heads so could be not matching up right to the stock intake.

                      Ignition seems o/k, car runs very cool for a big block, about 190 degrees, does not smoke oil. So, I'm down to intake / carbs / vacuum.

                      Any other thoughts appreciated.

                      Thanks, Doug
                      Gee, seems to me changing to the correct PCV would be a lot easier than R&R the intake. I would change the PCV first and see what happens -- but that is just me. I am kind of lazy.
                      Terry

                      Comment

                      • Douglas C.
                        Very Frequent User
                        • August 31, 1990
                        • 384

                        #12
                        Re: 69 L-68, oil puddle in the intake.

                        Originally posted by Duke Williams (22045)
                        It may not be oil - but condensed high boiling point components of the gasoline. Is the heat riser passage blocked? You need to go out and get the engine up to operating temperature for at least 30 minutes. The check again for the puddle.

                        Duke
                        Thanks Duke, but see above where I mentioned I pulled the carbs already. I will check free movement of heat riser, good thought there.

                        Tks. Doug

                        Comment

                        • Duke W.
                          Beyond Control Poster
                          • January 1, 1993
                          • 15670

                          #13
                          Re: 69 L-68, oil puddle in the intake.

                          I'm not talking about the valve, but you should check it for proper operation. Actually, you should wire it full open.

                          I'm talking about shims installed between the inlet manifold and head that completely block the crossover passage.

                          If the passage is blocked with shims the heat riser valve MUST be wired open. Otherwise, when it is closed at start up there is no place for the RH exhaust to go. This will definitely cause poor operation when the entire RH exhaust system is plugged up.

                          Duke

                          Comment

                          • Douglas C.
                            Very Frequent User
                            • August 31, 1990
                            • 384

                            #14
                            Re: 69 L-68, oil puddle in the intake.

                            Originally posted by Duke Williams (22045)
                            I'm not talking about the valve, but you should check it for proper operation. Actually, you should wire it full open.

                            I'm talking about shims installed between the inlet manifold and head that completely block the crossover passage.

                            If the passage is blocked with shims the heat riser valve MUST be wired open. Otherwise, when it is closed at start up there is no place for the RH exhaust to go. This will definitely cause poor operation when the entire RH exhaust system is plugged up.

                            Duke
                            O/k Duke, yep, good points. I'll check this.

                            Now also, my car currently has what looks like cheapo valve covers, probably incorrect oil baffle for the PCV, plus I currently have a CV746 PCV in there.

                            I wonder if the correct valve covers (Cranes?) with the proper baffle and a correct CV736 PCV would make a big difference in oil maybe being drawn into the intake.

                            Tks. Doug

                            Comment

                            Working...
                            Searching...Please wait.
                            An unexpected error was returned: 'Your submission could not be processed because you have logged in since the previous page was loaded.

                            Please push the back button and reload the previous window.'
                            An unexpected error was returned: 'Your submission could not be processed because the token has expired.

                            Please push the back button and reload the previous window.'
                            An internal error has occurred and the module cannot be displayed.
                            There are no results that meet this criteria.
                            Search Result for "|||"