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correct 69 427 engine mounts

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  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43193

    #16
    Re: correct 69 427 engine mounts

    Mark-----

    I would definitely be interested in knowing the configuration of the shield. A photo would be very nice.

    That shield will tell us a lot. If it's a shield for a locking style mount and has not been modified to fit, then it's further evidence that these motor mounts may have been factory-installed. It seems unlikely that if the motor mounts were installed post-PRODUCTION, that someone would have gone to the bother of ordering a new heat shield with the mounts. They, most likely, would either have modified the shield to fit (if that's even possible) or simply left it out.

    It's also possible, if the shield is modified, that it was done at St. Louis. There could have been instructions to "re-work" the shield until the new design became available. I consider this less likely, but possible.

    If your car does not have A/C them it should definitely NOT have the "V" shims. However, the fact that you have the shield, supports the notion that big blocks came with the shield regardless of A/C which is what GM says is the way it was.
    In Appreciation of John Hinckley

    Comment

    • Greg L.
      Extremely Frequent Poster
      • March 1, 2006
      • 2291

      #17
      Re: correct 69 427 engine mounts

      Joe,

      Here are some pics of the heat shield.

      It doesn't look to be altered in any way however the side with the bolt hole(or what remains of the bolt hole) is slightly distorted where the mount to engine bolt goes.




      This pic shows the only marking that I could see. It is "D.L. AULD"


      If you need any pics from other angles please let me know. So what do you think...could these mounts have actualy been installed in an early 69?

      Greg
      Attached Files

      Comment

      • Joe L.
        Beyond Control Poster
        • February 1, 1988
        • 43193

        #18
        Re: correct 69 427 engine mounts

        Greg------

        The shield pictured is the 68-69 style shield. There was originally a bolt hole on both sides. The right side hole has obviously deteriorated from galling caused by the bolt head. However, it looks like the left side hole ear was cut off. This may have been necessary to make the 69 style shield work with a locking-style mount-----I don't know, for sure, since I've never checked fitment of an early shield on a locking style mount. Thinking about it, though, it would seem that the early style shield should fit the later style mount without alteration although it would not provide the mount with the same degree of heat protection.

        Anyway, nothing definitive has yet been established here. The shield could have been altered at St. Louis or it could have been modified later if the mounts were replaced. However, I just have a feeling that these mounts and shield were both installed at St. Louis. It might deviate from "conventional wisdom", but, everything considered, it just "feels that way to me".

        A few more things to check:

        1) Check the configuration of the shield on the "missing bolt hole" side. Does the ear appear to have been removed cleanly? In other words, is there any evidence that the ear was "field removed" subsequent to its manufacture?

        2) What is the bolt head configuration of the 6 (3 each side) mount-to-engine bolts? Are they all the same?

        3) What is the configuration of the long, through bolt and the nut? Is the nut a "Stover-style" self-locking nut? Does the through bolt have a pilot tip (i.e. semi-pointed)?

        None of these things will, unfortuntely, be definitive. During a "transition" period of motor mounts which may have occurred during the 1969 model year, just about anything could have happened at St. Louis. This sort of situation can create "instabilities" which could result in all sorts of non-standard and unexpected "goings on". However, the more information we get, the better we MIGHT be able to piece things together.
        In Appreciation of John Hinckley

        Comment

        • Greg L.
          Extremely Frequent Poster
          • March 1, 2006
          • 2291

          #19
          Re: correct 69 427 engine mounts

          Joe

          Here is a pic of my hardware.


          The bolts that attach the mount to the block have the captured washers. The head's surfaces are recessed and are marked with an "E" on the shorter ones and an "anchor" on the longer ones. The longer ones are about a thread and a half longer.

          I also noticed in the AIM that the heat shield was to be installed with "production bolts" but in additional it was to have a extra washer under each bolt that the side without the heat shield should not have had. Maybe this is why there are two different length bolts. I don't recall these "extra" washers when I pulled the engine back in the eighties but if they had been installed I probably would not have reinstalled them, thinking they didn't belong.


          As for the heat shield, the cut off portion looks like it has been sheared. It is nice and straight with clean corners. The edge of it looks like the edges of the rest of the shield and I don't see any evidence of tin snips, file or grinding marks.

          One interesting note is how well the cut off side fits the mount. I don't know of any general mechanic, myself included when I work in a garage, that would take such great care to make such a "insignificant piece" look so good. It would have been quickly hack sawed or tin snipped so that it fit and called good enough!

          It would be nice to see if anyone else has come across this same configuration during this production time frame.

          So Joe, what is your best guess...could these mounts have been installed on the line?

          Greg
          Attached Files

          Comment

          • Joe L.
            Beyond Control Poster
            • February 1, 1988
            • 43193

            #20
            Re: correct 69 427 engine mounts

            Greg------

            Well, the mount-to-engine bolts definitely appear to be PRODUCTION pieces. Of course, someone could have transferred them from the original mounts to these. In any event, they did not "lose-and-replace" any in the process. If one or more of the bolts had been obviously non-PRODUCTION, that would have been pretty clear evidence that the mounts had been replaced at some point.

            The long bolt could be PRODUCTION or SERVICE. Different bolts were used for the non-locking and locking mounts. Whether installed in PRODUCTION or SERVICE, the bolts would had to have been the right ones for the mount. Have these bolts been replated? Most original bolts (and SERVICE bolts, for that matter) that I've seen are black-oxide finished. The configuration of the bolt, nut and washers is correct for either PRODUCTION or SERVICE.

            The shield is interesting. If it was "made this way", then I would have to say that it's some sort of "interim" style PRODUCTION shield. I don't really understand why the "ear" was eliminated from the left side, though. It would seem to me (perhaps, incorrectly, though) that the 68-69 style shield would fit as-is on the locking style mount. However, the fact that this is some sort of "special" shield would seem to indicate that it was factory-installed. If it was factory installed, "special" shield, there had to be some reason for it and the only reason I can think of is to be compatible with a change in the engine mounting. So, once again, this leads to the conclusion that the engine mounts did change for PRODUCTION during the 1969 model year. However, did they change to the mounts you have or was there some other mount of unknown configuration that originally resided on your car. I REALLY wish that someone could come up with a GM drawing of the 3967767 engine mount. That would anser a LOT of questions here.

            Another curious thing: while the left side shield "ear" with mounting hole is shown in the AIM drawing, you will note that there is no "bolt line" shown for the left side hole. It's possible that this was just an error, but it does IMPLY that, perhaps, the left side of the shield was not to be retained by a bolt. The 1968 AIM for the same sheet DOES show a "bolt line". So, what's the mistake on the 1969 page---the failure to show the "bolt line" OR showing the left side "ear" on the shield? In any event, the part number for the shield is the same for both the 1968 and 1969. One would think that if the shield was revised (i.e. the left side "ear" removed), then there would have been a different part number. But, maybe not.

            I completely understand the need for the addition of the flatwasher when the shield is installed. The flatwasher helps prevent the galling of the ALUMINUM shield. Considering the condition of the right side "ear" on your shield, it may well be that no flatwasher was ever installed. Of course, it's also possible that, if the mounts were replaced, it was then that the flatwasher was left out and that's what caused the galling of the shield. The condition of the shield does look like a bolt has been run down against it on multiple occasions----it's hard to imagine that it would get like this from just the original, St. Louis installation. So, this implies the bolts have been off and on more than once. The only reason I could imagine for this would be to have replaced the mount.

            So, there are indications both ways as far as originality of these mounts go. Like I say, though, I just have a "feeling" that they may well be original.

            It would be nice to hear from some other folks who have what they believe to be original motor mount installations on 1969 models. What would be particularly interesting is original big block cars, regardless of when built, and later 1969's, both small block and big block. As I mentioned, I know that my Septemeber, 1969-built small block had the non-locking mounts originally installed; I'm 100% sure of that. However, what happened after that time or what was possibly used on big blocks, I don't know.

            1969 is the only year in question here. I'm very confident that all 1963-68 Corvettes, big block or small block, received the non-locking style mounts. I'm just about as confident that all 1970 and later Corvettes used the locking style mounts.
            In Appreciation of John Hinckley

            Comment

            • Greg L.
              Extremely Frequent Poster
              • March 1, 2006
              • 2291

              #21
              Re: correct 69 427 engine mounts

              Joe

              Yes I was quite sure that all the hardware was original and yes the mount to frame hardware has been replated. I'm pretty sure though that either I could still see cad on it or was recommended from someone on the forum that they should be cad. If I couldn't determine the correct fastener finishes in my resto from the part itself, I would post the question on this forum. I still have lot to learn about these cars and didn't want to make the "wrong guess". If you are quite certain however that cad is incorrect then I'll change them to black.

              I had a good look at the damaged ear today and it appears to have been broken off. It is mashed and swelled a bit from tightening the bolt but that doesn't appear to be why the end is missing. The end of it is a clean break on one end and sort of a tear on the other. Again I don't 100% remember if this piece was there or not way back when but if it had fallen or was torn off when I had the engine out I wouldn't have given it a second thought. Anyways my point is that if the ear was damaged from bolt R&R then it would have to have been removed and installed many times to do that kind of damage and what remains of the ear should be totaly mashed and gauled which is not the case...it broke and was torn away. Then when it was reinstalled the tightening of the bolt spread the opening to look even worse.

              Any other thoughts?

              Greg

              Comment

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