Lower distributor shaft issue.

[philcobill]

I am considering changing out the lower distributor shaft while putting the new cylinder head back on the engine. The top one in the second photo is the old shaft and the other one is a "new" shaft. The old shaft has some surface rust and pitting. Additionally, the slots are wider than the new ones. I compared the "new" one with the "old" one in the block and because of the width difference, the new one has less rotational play in it and feels tighter, and I would like to use it if I can. However, the slots on the ends of the old one is 90 degrees off (out of phase) from each other, and the slots on the ends of the new one are 180 degrees off (out of phase) from each other. I am not sure if this in intentional. I am imaging that this might cause problems when timing the distributor. Or will it? Is this a manufacturing error?

You can see what I am talking about by looking at the photos.

What is going on here? Is this something that I should be concerned about?

[Brentwood Bob]

That is the design so the distributor can be removed and installed in only one way, and the timing unique to the motor, will not change.
And yes, you will need to refit the replacement shaft.
Test fit so the shaft slots mesh, and the distributor does sit flush on the head. Compare the dimensions of the old shaft with the replacement. The block, and/or the head have probably been shaved/decked and a taller replacement shaft will cause you problems.

[aermotor]

Originally Posted by Brentwood Bob

That is the design so the distributor can be removed and installed in only one way, and the timing unique to the motor, will not change.
And yes, you will need to refit the replacement shaft.
Test fit so the shaft slots mesh, and the distributor does sit flush on the head. Compare the dimensions of the old shaft with the replacement. The block, and/or the head have probably been shaved/decked and a taller replacement shaft will cause you problems.

I have never seen this and don't really understand the above explanation. The original shafts have both ends with offset but on the same plain. Hence, time a spare distributor to your car, toss it under the seat and if you get caught with a failure just drop in the spare, you are timed and ready go on your way. I believe the one with the slots 90 degrees to the other one must be a manufacturing error or for a different engine, but that doesn't make sense because if the car was running it must have had a non- original distributor. The length to compensate for different head thickness has nothing to do with the slots.

John

[Patrick L.]

I really don't see a problem. Just make sure the shafts fit and the distributor[s] fits as it/they should. If you want 2 distributors to work [ one as a spare] just time both and they should be interchangeable. Thats what the adjustable/settable distributor points cam is for. At least thats my take on this if I understand the problem correctly.

[john charlton]

If you install the new shaft the engine will not run it will be out of time . This is what I would do fit the old shaft and the distributer you need not rotate the engine . Take a good look where the rotor is pointing at even take a pic with your phone . Fit the new shaft you will see it is pointing in a different direction loosen the big screw and rotate the rotor to the same position as you had with the old shaft . The motor is now timed as before and you are good to go !!!

John in Suffolk County England

[PC/SR]

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Adjusting and setting the points cam and rotor will self-correct any problem.

[PC/SR]

Adjusting and setting the points cam and rotor will correct any problem.

[Patrick L.]

6 responses saying the same thing.

[J Franklin]

I think the orientation was not considered as a factor in manufacturing as it doesn't matter and isn't necessary.