1967 W108 250SE Distributor query

[Tassie Tiger]

Hi all,
I am seeking some advice on how to correctly reinstall the distributor drive shaft segment. I have turned the crankshaft pulley so that the pointer is at 6 degrees BTDC and #1 piston is on its compression stroke. How do I need to insert the drive shaft segment so that when it meshes with the auxilliary shaft gear, it is the correct orientation for the distributor to be inserted?
Also there is a graduated scale at the base of the distributor that has the letters F and S at each end of the scale. What does this mean? I would appreciate your comments.

Regards,
Tassie Tiger

[t walgamuth]

i will try to help from memory.

the bottom of the dist is a multi toothed gear. right? and the teeth are twisted? so you have to by trial and error put it in so that when it seats it twists into the right position. that will be pointing at the number one cylinder spark lead.

the minor adjustment on the bottom is for retarding the spark when you traveled south in europe to africa back in the sixties and the gas was a lot lower octane back then. to eliminate ping.

good luck, sounds like a nice car.

tom w

[ctaylor738]

There is also a small vertical mark on the side of the distributor marking the position of #1, at which the rotor will point when you have the correct position.

[Arthur Dalton]

Your dist does not have a gear at the bottom of the shaft .. it has a slotted drive coupling and can only go one way..if you look close, you will see that the drive dogs of the coupling are slightly off-center from the shaft C/L.

The gear with the mating slot to fit the dist shaft is under a sping in the dist mount hole. It can be turned with a wide blade screwdriver [ clockwise] in 40 degree increments. As you turn it , it will rise from the helix of the timing gear and drop back down to the next position.
To determine the position, you want TDC on compression stroke and dist rotor to face the indicator index mark on the dist. housing circumference.

So , line up the rotor with dist out and see the approx angle you want the gears slot to be at to accept the dist , noting the off-set of the slot.
[ otherwise you will be 180 out]
When all is correct , you will have TDC at compression and rotor facing index mark on dist housing.

The actual timing tweaking is then done with a strobe light and dist rotation. The index marks at base of the dist. [ F and S] ..which are for Retard/Advance adjustment without using a timing light. Each increment is 2 degrees. That is for octane adjustments when traveling in Foreign countries
where you could change the timing and be able to reset it according to octane ratings . You do not need to be concened with this if you use the same gas all the time.
Remember to reinstall the little spring on top of the gear, as this keeps the gear tight on the main drive from rising due to helix force. Failure to put the spring back in will affect both gear wear and ignition timing.. I see many where this spring is missing.....it should be there.

[t walgamuth]

oh yeah. that slotted and offset drive is excellent!

couldnt remember which was which. i should have looked at the book.

tom w

[Tassie Tiger]

Thank you for your replies.
This is excellent advice and I will give it a go over the next weekend.
Regards,
Tassie Tiger