Front mount Distributor Bushing tolerence.

i keep reading "If there is any play replace the bushings" But...What do you folks use as acceptable specs for bushing to distributor shaft tolerance for both front and back bushings?

I have a few distributors and trying to build a good back up unit before I monkey with my working one.
 
(quoted from post at 14:08:03 02/09/15) i keep reading "If there is any play replace the bushings" But...What do you folks use as acceptable specs for bushing to distributor shaft tolerance for both front and back bushings?

I have a few distributors and trying to build a good back up unit before I monkey with my working one.
ruce has all the specs on that, but for me, if forcing the shaft laterally with hand pressure doesn't change my point gap by more than about 1 or maybe even 2 thousands of an inch, I'm leaving it as is.
 
(quoted from post at 14:57:39 02/09/15)
(quoted from post at 14:08:03 02/09/15) i keep reading "If there is any play replace the bushings" But...What do you folks use as acceptable specs for bushing to distributor shaft tolerance for both front and back bushings?

I have a few distributors and trying to build a good back up unit before I monkey with my working one.
ruce has all the specs on that, but for me, if forcing the shaft laterally with hand pressure doesn't change my point gap by more than about 1 or maybe even 2 thousands of an inch, I'm leaving it as is.

Ok...Thats tighter than a gnats behind.!!!
Thought it may have been a bit more. But than again +/-.002 would give a range of .013 - .017 on a properly gapped point.

Now for a dumb question.
I ordered a few bushings but need to know what exactly are you using to ream out the bushings to fit your distributor shaft. There could be many different shaft widths due to wear so how many reamers do you need to have?

I'm thinking of using an expanding sand roller on the end of a drill press.
The press is a free standing 50 yr old commercial press weighs about 250lbs that has an extremely tight tolerance since I have replaced the bearings.

Thoughts???
 
You need TOH on that question, but I think a sandroll will follow the bushing & not 'true' up any geometry.
 

Yes that is what I am afraid of. I did just that on the front spindle bushings but the tolerance and exactness there is no where near as important.
 
So I have this same question now, as I just received front and rear bushings that I had intended to press fit in w/ a bench top press. Am I going to need to do something to make the rotor shaft fit properly? I had assumed everything was to the correct tolerances. The manual just says replace bushings if there's play.
 
Received the new front and rear bushings today and after pressing old ones out, new ones pressed right in.
Assembled the dist shaft, breaker plate and plate clip back together and gave it a finger spin test.

So just wondering what is considered acceptable resistance when spinning the shaft by hand. It will not free wheel rather I do feel a slight amount of drag but no binding.
 
(quoted from post at 23:53:20 02/11/15) Received the new front and rear bushings today and after pressing old ones out, new ones pressed right in.
Assembled the dist shaft, breaker plate and plate clip back together and gave it a finger spin test.

So just wondering what is considered acceptable resistance when spinning the shaft by hand. It will not free wheel rather I do feel a slight amount of drag but no binding.

Your shaft is a lubricated "running fit" in the bushing and ideally you should have .001/.002 diametric clearance. The Ford 120 Industrial Engine Manual has a whole section devoted to how Ford designed and specified their fits and tolerances and is recommended reading;-) The paragraph below is what it has to say about running fits.

TOH

Running%20Fit.jpg
 
(quoted from post at 14:12:33 02/09/15)
(quoted from post at 14:57:39 02/09/15)
(quoted from post at 14:08:03 02/09/15) i keep reading "If there is any play replace the bushings" But...What do you folks use as acceptable specs for bushing to distributor shaft tolerance for both front and back bushings?

I have a few distributors and trying to build a good back up unit before I monkey with my working one.
ruce has all the specs on that, but for me, if forcing the shaft laterally with hand pressure doesn't change my point gap by more than about 1 or maybe even 2 thousands of an inch, I'm leaving it as is.

Ok...Thats tighter than a gnats behind.!!!
Thought it may have been a bit more. But than again +/-.002 would give a range of .013 - .017 on a properly gapped point.

Now for a dumb question.
I ordered a few bushings but need to know what exactly are you using to ream out the bushings to fit your distributor shaft. There could be many different shaft widths due to wear so how many reamers do you need to have?

I'm thinking of using an expanding sand roller on the end of a drill press.
The press is a free standing 50 yr old commercial press weighs about 250lbs that has an extremely tight tolerance since I have replaced the bearings.

Thoughts???


The only bushing I know of that needs reamed or reduced is the oil pump bushing . If your distributor shaft is too loose you would replace it or make a custom bushing on a lathe .

If you pluck a hair from you head and measure it with a micrometer you will find it is between 3 - 4 thousandths / .003 - . 004
 

New bushings are in and not reamed. My question is what is considered too tight?
Or...
As long as the bushing was able to fit over the shaft than it is OK.

Dan, Thanks I am sure its good reading. Cant get to it from work due to firewall.
 
(quoted from post at 14:52:04 02/12/15)
New bushings are in and not reamed. My question is what is considered too tight?
Or...
As long as the bushing was able to fit over the shaft than it is OK.

Dan, Thanks I am sure its good reading. Cant get to it from work due to firewall.

Lubricate it with oil and it should turn with virtually zero resistance.

TOH
 

Actually that is exactly what I did and it did have much less resistance.
Thought that since these bushing are already impregnated with oil the initial resistance should be negligible.
Do not want to change bushings again if I don't have to.

TX Dan
 
(quoted from post at 15:06:33 02/12/15)
Actually that is exactly what I did and it did have much less resistance.
Thought that since these bushing are already impregnated with oil the initial resistance should be negligible.
Do not want to change bushings again if I don't have to.

TX Dan


The oil in impregnated bronze bearings is brought to the surface by pressure, capillary action, and frictional heat from the rotating shaft and returned to the pores via that same capillary action when the shaft is at rest.

TOH
 

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