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Author Topic: What are the crankshaft thread sizes on a 1972 HP .40 engi  (Read 1768 times)

Offline frank mccune

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What are the crankshaft thread sizes on a 1972 HP .40 engi
« on: May 22, 2015, 03:59:05 PM »
     Anybody know what these are?

                                                                                                                                                           Tia,

                                                                                                                                                           Frank McCune
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Online Robert Zambelli

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Re: What are the crankshaft thread sizes on a 1972 HP .40 engi
« Reply #1 on: May 22, 2015, 04:26:00 PM »
I have one from the early 70s (not too sure exactly what year) and it has a 1/4-28 UNF thread.

  Bob Z.
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Offline frank mccune

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Re: What are the crankshaft thread sizes on a 1972 HP .40 engi
« Reply #2 on: May 22, 2015, 06:29:25 PM »
      Hi Bob:

      The crankshafts that I am attempting to find nuts for are from circa 1972.  They are not 1/4-28!  They are close to M6X1 but not quite!  Perhaps my metric tap and die set was made poorly.

                                                                                                                                                                              Thanks for the reply,

                                                                                                                                                                              Frank
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Online RandySmith

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Re: What are the crankshaft thread sizes on a 1972 HP .40 engi
« Reply #3 on: May 22, 2015, 09:27:43 PM »
HP 40 cranks  are 6mm

Randy
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Offline frank mccune

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Re: What are the crankshaft thread sizes on a 1972 HP .40 engi
« Reply #4 on: May 23, 2015, 06:42:54 PM »
     Hi Randy:

     I can not get a 6x1 tap or die to work with either the prop nut or the threads on the crankshaft.  They will go on for about three threads and then get too tight to turn.  It feels like the pitch is incorrect.

     The  6x.75 t&d  will not begin to fit either the nut or the crankshaft.  My thread pitch gage tells me that the pitch is indeed a 1 pitch on the crankshaft.

     Like I have stated, perhaps my t&d are poor quality.

     Perhaps these threads are not SAE or Metric.

     Suggestions?

                                                                                                                                                         Stay well,

                                                                                                                                                         Frank
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Offline frank mccune

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Re: What are the crankshaft thread sizes on a 1972 HP .40 engi
« Reply #5 on: May 24, 2015, 05:14:43 PM »
     Hi:

     I bought a package of 6x1 metric nuts today and guess what? My tap will not enter the nuts despite being marked 6x1!  The nuts fit very well on the HP engine.  Conclusion, my tap is incorrect!  I will bet that the 6x1 die is also faulty as it will not thread on to the crankshaft threads despite being marked 6x1. Now I am suspect of the entire die plate!

     It is off to the store to see if I can find a new tap and die. Lol

                                                                                                                                    Stay well,

                                                                                                                                    Frank

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Online RandySmith

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Re: What are the crankshaft thread sizes on a 1972 HP .40 engi
« Reply #6 on: May 24, 2015, 09:32:17 PM »
Quote from: frank mccune on May 23, 2015, 06:42:54 PM
     Hi Randy:

     I can not get a 6x1 tap or die to work with either the prop nut or the threads on the crankshaft.  They will go on for about three threads and then get too tight to turn.  It feels like the pitch is incorrect.

     The  6x.75 t&d  will not begin to fit either the nut or the crankshaft.  My thread pitch gage tells me that the pitch is indeed a 1 pitch on the crankshaft.

     Like I have stated, perhaps my t&d are poor quality.

     Perhaps these threads are not SAE or Metric.

     Suggestions?

                                                                                                                                                         Stay well,

                                                                                                                                                         Frank


No they are  a  6mm  metric  thread, is your crank threads  messed up?

Randy
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Offline frank mccune

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Re: What are the crankshaft thread sizes on a 1972 HP .40 engi
« Reply #7 on: May 25, 2015, 05:31:23 AM »
      Hi Randy:

       Good to hear from you.

       No, the threads are not messed up.  The engines that I am speaking of are the ones that you just reworked.

       I do think that both my tap and die will not work. The problem may lie with the t&d being incorrectly made.  The only way that I can think of checking my t&d is to try another t&d and see if the new ones work.  I have never had a bad tap or die but there is a first time for everything.


                                                                                              Stay well my friend,

                                                                                              Frank
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Offline frank mccune

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Re: What are the crankshaft thread sizes on a 1972 HP .40 engi
« Reply #8 on: June 08, 2015, 07:15:41 AM »
     Hi All:

     Good news! My tap and die each had a "burr" on them.  After forcing them to cut on a 6 X1 screw and nut, the burr had broken away and now they each work very well.   I have ever seen  bad t&d before but I guess that nowadays due to what seems to be low quality of just about every product, why would I not be surprised?

                                                                                                                                               All is well again,

                                                                                                                                               Frank
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Online RandySmith

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Re: What are the crankshaft thread sizes on a 1972 HP .40 engi
« Reply #9 on: June 08, 2015, 09:49:36 AM »
Quote from: frank mccune on May 25, 2015, 05:31:23 AM
      Hi Randy:

       Good to hear from you.

       No, the threads are not messed up.  The engines that I am speaking of are the ones that you just reworked.

       I do think that both my tap and die will not work. The problem may lie with the t&d being incorrectly made.  The only way that I can think of checking my t&d is to try another t&d and see if the new ones work.  I have never had a bad tap or die but there is a first time for everything.


                                                                                              Stay well my friend,

                                                                                              Frank

ok those two are good, i put the correct metric nut on them, they both have good threads,
and yes  today i see many  bad taps and dies

Randy
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