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Old 07-22-2019, 05:18 PM   #1
Humperhill
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Default Rotation play in distributor shaft

I recently picked up a speedster built on a '30 chassis and drive train. Working through issues and have found that the distributor shaft has a good 25 degrees of rotation/play in it. I can only surmise that this play would be from where it sets in the gear in the block? Any ideas/suggestions? How much rotation play is acceptable? Les Anderson book say some platy is okay. Some is pretty relative as you know. Thanks for your help. Eric
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Old 07-22-2019, 05:31 PM   #2
Brentwood Bob
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Default Re: Rotation play in distributor shaft

Sounds excessive. The lower end of the distributor shaft does fail. Originally the shaft is a 2 part shaft. If you go deeper, the driver teeth wear, and even the meshing gear on the cam.
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Old 07-22-2019, 06:19 PM   #3
Y-Blockhead
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Default Re: Rotation play in distributor shaft

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Originally Posted by Humperhill View Post
I recently picked up a speedster built on a '30 chassis and drive train. Working through issues and have found that the distributor shaft has a good 25 degrees of rotation/play in it. I can only surmise that this play would be from where it sets in the gear in the block? Any ideas/suggestions? How much rotation play is acceptable? Les Anderson book say some platy is okay. Some is pretty relative as you know. Thanks for your help. Eric
25 is alot. You could have a Phillips/Nu-Rex auto advance kit installed. It takes place of your lower shaft. It is set to advance your timing 30 BTDC. I have one in my Sedan and yes you can turn the distributor shaft ~15.

https://www.snydersantiqueauto.com/P...earchByKeyword

http://www.fordgarage.com/pages/nurexadvance.htm
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Old 07-22-2019, 06:54 PM   #4
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Default Re: Rotation play in distributor shaft

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Originally Posted by Y-Blockhead View Post
25 is alot. You could have a Phillips/Nu-Rex auto advance kit installed. It takes place of your lower shaft. It is set to advance your timing 30 BTDC. I have one in my Sedan and yes you can turn the distributor shaft ~15.
Possible, but if you have one it should (a) be obviously present when the valve cover is removed and (b) be spring-loaded, so the play should snap back when you let go. I also have one (they're great). If you have one and it isn't springing back, you should remove/replace it.
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Old 07-22-2019, 07:11 PM   #5
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Default Re: Rotation play in distributor shaft

I do have an auto advance but not the Nu-Rex type. The lower plate actually has centrifugal weights and spring loaded. While I do have that sprung movement with the rotor it snaps back. The above movement is in addition to this and does not snap back. I have not removed the valve cover as of yet.
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Old 07-22-2019, 11:08 PM   #6
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Default Re: Rotation play in distributor shaft

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Quote:
Originally Posted by alexiskai View Post
Possible, but if you have one it should (a) be obviously present when the valve cover is removed and (b) be spring-loaded, so the play should snap back when you let go. I also have one (they're great). If you have one and it isn't springing back, you should remove/replace it.
This is true, but as far as we know from post #1 the OP has not removed the valve cover... yet. Nor did he say it snapped back. I was just making a suggestion as to why he might have so much movement. https://youtu.be/_dnBoiVobO8

Quote:
Originally Posted by Humperhill View Post
I do have an auto advance but not the Nu-Rex type. The lower plate actually has centrifugal weights and spring loaded. While I do have that sprung movement with the rotor it snaps back. The above movement is in addition to this and does not snap back. I have not removed the valve cover as of yet.
Sounds like you may have a "B" distributor with centrifugal advance. A "B" distributor advances 8 (17 crank advance).

If you have 25 movement in addition to what the distributor advances I would venture to guess you have some serious wear problems...
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Old 07-23-2019, 06:43 AM   #7
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Default Re: Rotation play in distributor shaft

I just had the same problem,it turned out to be the base of the distributor shaft and also the intermediate shaft. Both ends on the intermediate shaft were worn badly as was the distributor drive area.
I machined up a Mallory to suit the 29 motor and made a new intermediate shaft,
Problem solved.
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Old 07-23-2019, 08:40 AM   #8
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Default Re: Rotation play in distributor shaft

B distributor..hook a timing light to it chalk mark your crank pulley and rev the engine,the mark should 'move'
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Old 07-23-2019, 03:40 PM   #9
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Default Re: Rotation play in distributor shaft

Well I have ordered a distributor rebuild lit from Synders and will tear into it this weekend to see where the slop is coming from. Thanks for all your input and help. Eric
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Old 07-23-2019, 03:43 PM   #10
Bob C
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Default Re: Rotation play in distributor shaft

Don't forget to check the distributor-oil pump drive gear.


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Old 07-23-2019, 08:23 PM   #11
barrelnose
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Default Re: Rotation play in distributor shaft

Just pull your distributor and with some fine nose pliers,pull the intermediate shaft.
Your distributor drive has a tang (offset)with a sleeve pinned over it to index the shaft and the shaft has a slot(offset) at each end .
You will see what’s worn straight away.
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Old 07-23-2019, 09:20 PM   #12
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Default Re: Rotation play in distributor shaft

Some vendors offer two oversize oil pump-distributor drive gears installed on the shaft. With one of these , all of the backlash can usually be removed .
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Old 07-24-2019, 09:53 AM   #13
Purdy Swoft
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Default Re: Rotation play in distributor shaft

The distributor shaft rides on the trailing side of the rotational play or backlash . Rotational backlash will cause no problem if the cam screw is tightened when rhe points cam is all the way back to the trailing side of the play or backlash after the cam screw is tightened .. In other words , NO backlash - rotational play should be allowed on the trailing edge of rotation of the distributor .
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Old 07-24-2019, 06:29 PM   #14
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Default Re: Rotation play in distributor shaft

Purdy Swoft, this was the logic I was thinking too since the gear is pulling the shaft/rotor. I will pull it all this weekend and will hopefully soon tell.
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