Changing position of the distributor - illustrated

[Jerome74911S]

In the photos below the cinch bolt of the distributor is all the way to the left in the adjusting slot.

I tried to rotate the distributor by one tooth, because previously the bolt was all the way to the right. I wanted the bolt somewhere in the middle, so that adjustment would be easier.

The crank is in the correct position. The engine is a '75 S.

Questions:

1) How much rotation of the distributor would one tooth provide? I tried it many times, but am I moving more than one tooth?

2) The "contact" tip of the rotor should point at the notch in the edge of the dizzy. But what part of that tip? It is the better part of 1 cm wide. Leading edge, middle, trailing edge?

3) What am I missing?

[Walter_Middie]

Jerome,

1.) Just move it one tooth and see how much more adjustment that gives you. Remember that the distributor rotates as you insert it, so be sure to compensate for that when you position it for installation.

2.) It doesn’t matter what part of the rotor points to the mark – just get it close. Start the car and adjust with a timing light at idle initially, then at 6,000 RPM for the correct position. Then if you need more adjustment, remove the dist and move one more tooth. It doesn't have to be in the middle - it only has to be able to adjust to where you want it at 6,000 RPM.

3.) What am I missing? Are you are thinking that the final position is the one that you chose to install at? It’s not. Just install it close enough to be able to start the engine and set with a timing light.

[Flat6pac]

There is 12 teeth on the bottom of the dist. the dist. turns one time to the engine 2 revolutions so there is 60 degrees between teeth.
Bruce

[Jerome74911S]

Originally Posted by Flat6pac

There is 12 teeth on the bottom of the dist. the dist. turns one time to the engine 2 revolutions so there is 60 degrees between teeth.
Bruce

Thanks, Bruce. I don't quite get it, though. If the dist rotates 180 degrees for each 360 by the engine, and there are 12 teeth, then 180 divided by 12 = 15 degrees per tooth. Is this wrong?

[Walter_Middie]

Jerome,

When the engine has rotated once, 360 deg, the dist has only moved 6 teeth, or 60 deg engine rotation per tooth.

[Jerome74911S]

Originally Posted by Walter_Middie

Jerome,

When the engine has rotated once, 360 deg, the dist has only moved 6 teeth, or 60 deg engine rotation per tooth.

Thanks, Walter, and Bruce. You guys must be right, but I still need to puzzle over it. It looks to me as if the range of adjustment is maybe 30 degrees (the size of the adjusting slot), so I'll have to scratch my head a bit more as I do more fiddling.

[Walter_Middie]

30 deg of distributor rotation. 60 deg of engine rotation.

[911pcars]

Originally Posted by Walter_Middie

30 deg of distributor rotation. 60 deg of engine rotation.

So as to not confuse, +1 on Walter's statement.

Try to position the hold down stud in the middle of the housing slot w/rotor tip pointed at no. 1 spark plug terminal on the cap. That should provide plenty of advance/retard range for static and 6000 rpm timing.

Sherwood

[Jerome74911S]

Yes, I'll give it a shot. Finally this is seeping through my thick skull, a few degrees at a time.