Distributor Shaft End Play

[KMBeers]

I have rebuilt the distributor for my 29 Tudor. The information in the Les Andrew’s book states there should be 0.005 endplay in the shaft. The rebuild kits come with an 0.015 thick steel shim and an .045 thick fiber washer that is supposed to go on the bottom just above the coupling. The gap that I was left with after assembly was 0.034. I bought extra 0.015 thick steel washers and installed one at the top and another one just above the coupling at the bottom. I left out the fiber washer. The end play is now 0.002 (the steel washers measured 0.016). I am thinking I am Ok to use this as is but I would love to hear some other’s thoughts on this who have more experience with the Model A engine.

[J Franklin]

Probably ok but you could have run the fiber washer a few strokes over some sandpaper to decrease its thickness.

[Bob Bidonde]

The end play, which allows vertical movement of the shaft, is not critical because of the height of the distributor cam. Also, the spring on the rotor contact puts a downward push on the shaft.

[KMBeers]

Thanks for the info. I was thinking that the distributor body would expand faster than the shaft (get hotter faster) and perhaps things might bind up or rub. Perhaps I will do the math and see what the temperature difference has to be to make the 0.002 go to zero and if that seems possible…. Thanks again for the help.

[KMBeers]

Ok, I ran the numbers and there needs to be 102DegF between the distributor body and the distributor shaft for things to bind up so I should be in good shape to use as is. Thanks everyone again for the help.

[J Franklin]

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102 degrees F is normal summer temps in some areas. I think you have something amiss.

[KMBeers]

Not sure I stated things as clearly as I could have. If the iron distributor body heated by the engine head gets to be 102F hotter than the shaft then the 0.002 clearance will go to zero. The chance of that happening is really low. Really has not much to do with the outside temperature other than the rate at which things get hot with the engine on or cool down after the engine is turned off.

[Y-Blockhead]

Originally Posted by KMBeers

Not sure I stated things as clearly as I could have. If the iron distributor body heated by the engine head gets to be 102F hotter than the shaft then the 0.002 clearance will go to zero. The chance of that happening is really low. Really has not much to do with the outside temperature other than the rate at which things get hot with the engine on or cool down after the engine is turned off.

I understood perfectly what you meant, I'm just not sure I woulsd have the gumption to figure it out, haha.

[Brentwood Bob]

So when I rebuilt the distributors I went snug, which should have been less snug. Bummer.
Guess the fiber washer gave me a little safety margin, and assembly lube would be a good idea. No returns yet. Guess that means no overheating going on.

[JayJay]

Originally Posted by Y-Blockhead

I understood perfectly what you meant, I'm just not sure I woulsd have the gumption to figure it out, haha.

Calcs are really not too difficult, I do them frequently when determining press fit dimensions.

[KMBeers]

I would really like to know what the basis was for the 0.005 clearance speced in the Les Andrew’s book. Some Ford engineer calculated that almost 100 years ago and it would be good to know what was the basis. Just a curiosity???

[Fullraceflathead]

It may have been a commonly used clearance and no real thought put behind it at the time.

[J Franklin]

Originally Posted by Fullraceflathead

It may have been a commonly used clearance and no real thought put behind it at the time.

I agree, just a measure of corporate safety.