3817173 harmonic balancer/crank timing gear mating issues.

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  • Tony S.
    NCRS Vice President, Director Region VII & 10
    • May 1, 1981
    • 956

    3817173 harmonic balancer/crank timing gear mating issues.

    I'm having some re-assembly issues with my 8" finned harmonic balancer during my engine build. Some suggestions are needed to figure it out. Here's what I have.

    I'm building a '65 L79 engine. I have the stock crank and the 8" harmonic balancer (part no. 3817173). The crank timing gear is .544 thick. The timing cover with 8" timing tab is in place. When I press on the harmonic balancer to seat up against the crank timing gear, the back side of the balancer fits too tight against the timing cover. I'm not sure if I need a thicker crank timing gear or what. Has anyone run into this before, or does anyone have any solutions?

    Thanks.
    Tony
    Region VII Director (serving members in Arkansas, Kansas, Louisiana, Missouri, Oklahoma and Texas).
    Original member of the Kansas City Chapter, est'd 07/11/1982.
    Member: 1965 and 1966 National Judging Teams
    Judging Chairman--Kansas City Chapter.
    Co-Editor of the 1965 TIM and JG, 6th and 7th editions.
  • Clem Z.
    Expired
    • January 1, 2006
    • 9427

    #2
    Re: 3817173 harmonic balancer/crank timing gear mating issues.

    run a search "timing gear" and you will see what was discussed before on this site. seems the run from .560 to .615 thick depending on type

    Comment

    • Tony S.
      NCRS Vice President, Director Region VII & 10
      • May 1, 1981
      • 956

      #3
      Re: 3817173 harmonic balancer/crank timing gear mating issues.

      Archives not much help.
      Region VII Director (serving members in Arkansas, Kansas, Louisiana, Missouri, Oklahoma and Texas).
      Original member of the Kansas City Chapter, est'd 07/11/1982.
      Member: 1965 and 1966 National Judging Teams
      Judging Chairman--Kansas City Chapter.
      Co-Editor of the 1965 TIM and JG, 6th and 7th editions.

      Comment

      • Clem Z.
        Expired
        • January 1, 2006
        • 9427

        #4
        Re: 3817173 harmonic balancer/crank timing gear mating issues.

        Comment

        • Joseph K.
          Expired
          • August 27, 2008
          • 407

          #5
          Re: 3817173 harmonic balancer/crank timing gear mating issues.

          I did run into this problem on a 69 350/350 rebuild. It turned out that the balancer was the wrong one. Apparently the previous owner went to the junk yard in 1980 and found a balancer off of a 350 engine and used it. He just did not tighten the balancer all the way. When I rebuilt the engine I ran into the same problem you had. I spent several months researching and going on line with no real anwser. By chance I went to a local parts store one day and there was a young guy behind the counter he took one look at it and said that it was off of a chevy 350 truck motor. Turns out he rebuilds chevy motors all the time. He ordered the right balancer for $45 and it worked like a charm. The truck balancer nipple was to short and the balancer bottomed out against the timming chain cover. Hope this helps.

          Joe

          Comment

          • Joe R.
            Extremely Frequent Poster
            • March 1, 2002
            • 1356

            #6
            Re: 3817173 harmonic balancer/crank timing gear mating issues.

            Hi Tony:

            For midyear small blocks, I believe the "depth" of the balancer is about 2.32 inches, as indicated in the attached photo. The dimension is the same for both the small balancer and the large one.
            Attached Files

            Comment

            • Joe L.
              Beyond Control Poster
              • February 1, 1988
              • 43133

              #7
              Re: 3817173 harmonic balancer/crank timing gear mating issues.

              Originally posted by Joe Randolph (37610)
              Hi Tony:

              For midyear small blocks, I believe the "depth" of the balancer is about 2.32 inches, as indicated in the attached photo. The dimension is the same for both the small balancer and the large one.

              Joe-----


              Is there a 4 digit number stamped on the face of this balancer? If it's there, it will be small font size.
              In Appreciation of John Hinckley

              Comment

              • Joe R.
                Extremely Frequent Poster
                • August 1, 1976
                • 4546

                #8
                Re: 3817173 harmonic balancer/crank timing gear mating issues.

                Tony,

                I have always used the truck chain and sprockets for my small block rebuilds with no problem. It works with both balancers with no problem.
                The part numbers are 3735411, 3735412 and 3735413. The heavy duty truck chain is very similar to the cloyes in appearance but is not a true roller as the split bushings don't roll.

                With the correct cover and balancer the above chain and sprockets will last for many miles.

                JR

                Comment

                • Tony S.
                  NCRS Vice President, Director Region VII & 10
                  • May 1, 1981
                  • 956

                  #9
                  Re: 3817173 harmonic balancer/crank timing gear mating issues.

                  Originally posted by Clem Zahrobsky (45134)
                  Clem. I do appreciate your efforts, but I called Cloyes and they tell me that their crank gear measures .547" in thickness. I need to pick up about 1/8". I'm considering just shimming the gear.
                  Tony
                  Region VII Director (serving members in Arkansas, Kansas, Louisiana, Missouri, Oklahoma and Texas).
                  Original member of the Kansas City Chapter, est'd 07/11/1982.
                  Member: 1965 and 1966 National Judging Teams
                  Judging Chairman--Kansas City Chapter.
                  Co-Editor of the 1965 TIM and JG, 6th and 7th editions.

                  Comment

                  • Joe L.
                    Beyond Control Poster
                    • February 1, 1988
                    • 43133

                    #10
                    Re: 3817173 harmonic balancer/crank timing gear mating issues.

                    Originally posted by Joe Ray (1011)
                    Tony,

                    I have always used the truck chain and sprockets for my small block rebuilds with no problem. It works with both balancers with no problem.
                    The part numbers are 3735411, 3735412 and 3735413. The heavy duty truck chain is very similar to the cloyes in appearance but is not a true roller as the split bushings don't roll.

                    With the correct cover and balancer the above chain and sprockets will last for many miles.

                    JR
                    JR-----


                    All of the above are now GM-discontinued.
                    In Appreciation of John Hinckley

                    Comment

                    • Mark P.
                      Very Frequent User
                      • May 14, 2008
                      • 934

                      #11
                      Re: 3817173 harmonic balancer/crank timing gear mating issues.

                      Anthony - if you shim it, were you planning to use the 1/8 Harmonic Balancer Spacer the C1 283's use ? The 1/8 keyed washer installs between the timing gear and harmonic balancer. You will have to make sure your pulleys still line up.

                      Mark
                      Attached Files

                      Comment

                      • Joe R.
                        Extremely Frequent Poster
                        • March 1, 2002
                        • 1356

                        #12
                        Re: 3817173 harmonic balancer/crank timing gear mating issues.

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


                        Is there a 4 digit number stamped on the face of this balancer? If it's there, it will be small font size.

                        Hi Joe L:

                        I checked, and the face of this balancer has "F B 7" stamped into the front face of the center casting, in characters that are slightly less than 1/8 inch tall. I do not see any other stampings.

                        This particular damper came off my 1967 327/300 HP engine that was assembled on March 17, 1967. I suspect it is the original damper, but I've only owned the car for five years.

                        By the way, the reason that this damper is on my bench instead of the car is that during a recent cam swap I noticed that the damper showed some degradation. Based on information you had posted here on the TDB, I decided to just buy the current GM part instead of trying to restore this one. The current GM part looks exactly like this one and cost about $40, as I recall.

                        Comment

                        • Joe L.
                          Beyond Control Poster
                          • February 1, 1988
                          • 43133

                          #13
                          Re: 3817173 harmonic balancer/crank timing gear mating issues.

                          Originally posted by Joe Randolph (37610)
                          Hi Joe L:

                          I checked, and the face of this balancer has "F B 7" stamped into the front face of the center casting, in characters that are slightly less than 1/8 inch tall. I do not see any other stampings.

                          This particular damper came off my 1967 327/300 HP engine that was assembled on March 17, 1967. I suspect it is the original damper, but I've only owned the car for five years.

                          By the way, the reason that this damper is on my bench instead of the car is that during a recent cam swap I noticed that the damper showed some degradation. Based on information you had posted here on the TDB, I decided to just buy the current GM part instead of trying to restore this one. The current GM part looks exactly like this one and cost about $40, as I recall.
                          Joe-----


                          The fact that it does not have the part number derivative (i.e. 6903) stamped on the face and it's configuration is pretty strong evidence that it's an original balancer (or, a GM SERVICE part of the original part number). Also, although I can't exactly de-code what is likely a date code, I expect the "7" refers to a 1967 manufacturing date..

                          Unfortunately, the GM #3896903 balancer is GM-discontinued without supercession.
                          In Appreciation of John Hinckley

                          Comment

                          • Timothy B.
                            Extremely Frequent Poster
                            • May 1, 1983
                            • 5173

                            #14
                            Re: 3817173 harmonic balancer/crank timing gear mating issues.

                            This is a picture of the damper on my 67 327/300 HP car. I believe it's original but I am not the original owner so I can't say for sure. This car is a September 66 build so I am not sure what the stampings mean..

                            Comment

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