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  • crank pulley thread

    I stripped the 3/8-24 thread on 1 of 3 retaining bolt holes....my helicoil kit only has 3/8 16. can I retap to that HC size and use a 3/8-16 bolt? Could I use a longer 3/8-24 bolt that would hold lock washer and nut on backside of balancer? Don't really have time to wait on amazon and can't locate locally (helicoil). Somebody please stop me from doing something stupid.400sbc ext balance . PowerTour in about 10 days, don't want to take the Challenger.
    Maybe I can clear this up.....I thought the cop was a prostitute.

  • #2
    I would just get another dampener


    Patrick & Tammy
    - Long Haulin' 2008, 2009, 2010, 2011, 2012, 2014...Addicting isn't it...??

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    • #3
      Thanks Patrick, but trying to use what I have....and not pull the dampener....and on the cheap.
      Maybe I can clear this up.....I thought the cop was a prostitute.

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      • #4
        if there's room for a nut on the backside I'd consider that and if it doesn't cause it to shake like a pig, keep it under 5k rpm? Balance is a higher rpm function the way I understand it.
        Flying south, with a flock of bird dogs.

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        • #5
          Originally posted by 173rdherd View Post
          Thanks Patrick, but trying to use what I have....and not pull the dampener....and on the cheap.
          . I can understand doing it in a frugal manner! However, balance is a very fickle mistress! I have seen cranks with minimal vibration last for years, but yet I have also seen them snap the end of the crank off which would be a catastrophic failure at the least! The choice is yours!
          Last edited by silver_bullet; June 3, 2022, 12:55 PM.
          Patrick & Tammy
          - Long Haulin' 2008, 2009, 2010, 2011, 2012, 2014...Addicting isn't it...??

          Comment


          • #6
            Thank you both....I am going to try a longer bolt of the same pitch and keep it very close in the back. I don't think the motor has seen 5k since i've owned it. To your point Patrick, if I sense any vibration on the shakedown I will swap it out.
            Maybe I can clear this up.....I thought the cop was a prostitute.

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            • #7
              sorry I am so late to the party. I don't think you would notice one being 3/8-16 and 2 being 3/8-24. The bigger issue for me would be remembering which was which. That might make me drill all three out and use 3/8-16 for all of them.

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              • #8
                If you do go with the through bolt solution you could always do all three with longer bolts, washers and nuts. I assume it is a fairly small bolt circle which will have less effect on balance and IF they are all the same (longer bolts) then I don't believe the balance will be changed at all. It typically is reciprocal balance so I don't believe adding a few extra grams concentrically is going to effect much of anything.

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                • #9
                  What the unknown was, could i retap for a helicoil of 3/8-16, as 3/8-24 is unavailable within my window.. I know that you could ruin a 3/8-24 hole with an air wrench and a 3/8-16 bolt, but if you could just retap the hole at 16, I don't know.
                  Maybe I can clear this up.....I thought the cop was a prostitute.

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                  • #10
                    Mike - trying to be sure I understand - you have in hand a 3/8-16 helicoil kit with drill, tap and helicoils?
                    IF so, then you should be able to drill out the 3/8-24 hole using the appropriate drill bit for the 3/8-16 helicoil and then cut the new helicoil threads - no issues.

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                    • #11
                      Originally posted by cstmwgn View Post
                      If you do go with the through bolt solution you could always do all three with longer bolts, washers and nuts. I assume it is a fairly small bolt circle which will have less effect on balance and IF they are all the same (longer bolts) then I don't believe the balance will be changed at all. It typically is reciprocal balance so I don't believe adding a few extra grams concentrically is going to effect much of anything.
                      I like this one.
                      Flying south, with a flock of bird dogs.

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                      • #12
                        no longer bolt, there isn't enough room behind the balancer - it will hit the pan... ask me how I know, I dare you... but don't you be whining about your virgin ears when I'm done.

                        why not tap to a larger bolt? OR, I've had several vehicles that were missing one of the three bolts.... OR, JB weld the bolt in place. The crank bolt is what holds the pulley in place, the bolts are just to keep it from rotating - point is, one would be sufficient.
                        Last edited by SuperBuickGuy; June 3, 2022, 10:19 PM.
                        Doing it all wrong since 1966

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                        • #13
                          Allen, you are correct, but after reading SBG input, the other two are locktited and as I suspected, they are only holding the pulley from rotating. I'm old, slow and running out of time. I will leave it as is, keep an eye on it and make a repair when time and money stars are aligned. Thanks again everyone!
                          Last edited by 173rdherd; June 4, 2022, 05:56 AM. Reason: because I can
                          Maybe I can clear this up.....I thought the cop was a prostitute.

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                          • #14
                            You still need the third bolt if you want to eliminate balance issues. I like the helicoil solution, then a dab of red paint or a nice centerpunch dimple would mark which hole is the -16 thread.
                            Ed, Mary, & 'Earl'
                            HRPT LongHaulers, 08, 09, 10, 11, 12, 13, 15, 16, 17, 18, 19.


                            Inside every old person is a young person wondering, "what the hell happened?"

                            The man at the top of the mountain didn't fall there. -Vince Lombardi

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                            • #15
                              Originally posted by oletrux4evr View Post
                              You still need the third bolt if you want to eliminate balance issues. I like the helicoil solution, then a dab of red paint or a nice centerpunch dimple would mark which hole is the -16 thread.
                              I have no proof of this - just decades of experience.... but I think that one small bolt near the center of the mass makes less difference to anything then anything. Start with balancing a stock crank - the imbalance allowed is greater then the weight of the bolt (2.41 oz or 46 grams). If we were talking a 8,000 plus rpm motor (even at 8,000 rpm, the 'mass' of that missing bolt is only 200 lbs at the edge of the balancer), sure, but a motor that redlines at 5k and lives at 2500 rpm - that little bit of imbalance won't make that much difference (and that's generous, I think it makes none at all).

                              to drill down further (yeah, a pun, so sue me)... imbalance of 1-2% is fine, 1-2% of 2550 grams (58 grams) and we're right to my point - that 46 grams won't make much, if any difference. Add to this that this is an externally balanced motor.... and I stand by my assertion that it makes no difference if it's there. Not in this case.
                              Doing it all wrong since 1966

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