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Old 12-15-2019, 10:52 AM   #1
Don/WI
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Default Distributor shaft screw size

What is the diameter and pitch for the distributor shaft screw? It does not seem to be anything standard. Thanks for any response. Don/WI
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Old 12-15-2019, 12:12 PM   #2
Jim Brierley
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Default Re: Distributor shaft screw size

If you are talking about the screw that holds the dist in the head, it is 3/8" N.F. thread.
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Old 12-15-2019, 12:25 PM   #3
David R.
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Default Re: Distributor shaft screw size

Are you talking about the cam screw? The one that goes in the top to lock the cam in place? I believe it is an odd size. The one that goes in block to lock the body down is 3/8-24.
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Old 12-15-2019, 12:34 PM   #4
Bob C
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Default Re: Distributor shaft screw size

The parts book show the distributor cam screw as A-20744 .325-30 U.S.F. x 25/64.


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Old 12-15-2019, 03:50 PM   #5
Benson
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Default Re: Distributor shaft screw size

don,


Something I learned the hard way ... pay attention to length of screw that Bob C posted!



If the screw is too long it will bottom out and cam will never get tight.


Originally Ford used a thin lock washer AND a thin flat washer.


If either one is missing, the screw will "bottom out" when using original Ford screw.


SOME of the recent Repro screws come with a THICK lockwasher (twice the thickness of Ford lockwasher and no thin flat washer.

Last edited by Benson; 12-24-2019 at 08:58 AM.
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Old 12-15-2019, 04:01 PM   #6
David R.
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Default Re: Distributor shaft screw size

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25/64” NF, good luck finding a tap for that at the box store! I had trouble pulling my distributor. I initially thought about fabricating a puller but the size of that thread gave me pause. I finally just kept tapping thin wedges alternately under each side while offering generous applications of penetrating oil.
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Old 12-15-2019, 04:36 PM   #7
Bob C
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Default Re: Distributor shaft screw size

25/64 is the length.
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Old 12-15-2019, 05:59 PM   #8
Don/WI
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Default Re: Distributor shaft screw size

Thanks guys, it was the distributor cam screw info that I was looking for. I should have been more explicit in my description. Don/WI
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Old 12-15-2019, 09:50 PM   #9
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Default Re: Distributor shaft screw size

That odd size screw is likely an old American Standard #20 extra fine thread. The American Standard system has been obsolete since 1949. The #20 major diameter is 0.321

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Old 10-17-2020, 07:03 PM   #10
walkerlakeprinter
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Default Re: Distributor shaft screw size

I discovered that my distributor cam screw was missing a washer. This might explain the problem I was having keeping the car in time. I installed a new cam and a thin washer that was on a spare distributor I had knocking around the shop. Is a lockwasher on top of the thin washer a good idea? Some suppliers carry them, and some don't.
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Old 10-17-2020, 09:31 PM   #11
Bob C
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Default Re: Distributor shaft screw size

The Ford parts book shows a washer and lock washer.
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Old 10-18-2020, 05:22 AM   #12
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Default Re: Distributor shaft screw size

.. and whilst we're on it why DID Ford originally put on a thin washer as well as a lock washer... does the washer serve any purpose? ( if it's to stop the screw bottoming out it surely it would have been cheaper $$ and quicker $$ to have a marginally shorter screw)

Last edited by johnbuckley; 10-18-2020 at 06:18 AM.
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Old 10-18-2020, 10:02 AM   #13
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Default Re: Distributor shaft screw size

Quote:
why DID Ford originally put on a thin washer as well as a lock washer
I would suspect that the thin flat washer is to protect the shaft from getting chewed up by the lockwasher.
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