distributor drive gear orientation
 

I am just about done my first rebuild a 12a that was pieced together out of two, when I went o finish off the assembly on the front of the eshaft in the front cover, I realized that neither of the distributor drive gears have the "f" mark that the haynes manual says to put forward, the only diffrence between the sides is that one is completely smooth and the other is brushed kinda like a freshly resurface (brake)rotor. when put side by side they look the same but when the key way is lined up there is a slight difference in where the gears sit. has anyone seen this before, or know which way to put it on with out the "F" mark?

With the front cover off, hold the dizzy in it's relative position and note the angle of the gears. Both the drive gear and the dizzy gear are helical cut gears. One way they mesh, the other way they don't. Iirc, the drive gear has a champer on the inner edge of one side. I 'think' that goes towards the engine.

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I didnt even notice the champer but its there, even with the front cover in place the gear seems to mesh up either way. the only difference is that oneway the gears are in a slightly different position.

I don't remember if the exploded assembly diagram in the FSM show the orientation of the chamfer of not. Most of the engines I've torn down do not have the F stamped on the gear.

No the fsm does not and I havent found any literature that does, does any body know which way it goes?
If i get no reply then I will likley put it towards the eng. like as trochoid seems to remember.
thanks for the help though.

Rotate engine to TDC (spin it clockwise) the first mark on the pulley that lines up with the pin on the font cover. Holding dizzy above the hole, rotate shaft until the flat side at the top is pointing forward or rearward. Or if the rotor is on it, the lower contacts point front and rear. Then stab it in. It will move a little because the dizzy gear teeth are slanted.

Note it is easier to static time with the rotor and aluminum cover removed. Observe the reluctor (little four-tipped thing down below). Again, make sure the flat part of the shaft is pointing forward or rearward. Let's just say forward to keep the description simple. Once the dizzy is fully seated, check that the tip of the reluctor (directly below the flat part in this case) is closest to the core of the forward-most pickup. This is the leading pickup. Note the other pickup on the rear side of the dizzy will be offset a few degrees. This is the trailing pickup and is the normal position for it. Also note that as the shaft rotates counterclockwise, which is the correct direction by the way, in a few degrees the other reluctor tip will pass the trailing pickup.

Adjust the dizzy housing until the forward pickup is closest to the front-facing reluctor tip. If you find the housing is really far in one direction or the other, you'll need to pull it back up, compensate by turning the shaft the distance of one tooth, and restab it. It should line up now. Notice the clean spot on the horizontal bracket should be right above the hole on the front cover. Install the 10mm bolt and snug it for now.

Fire it up and do your final timing adjustment with a timing light.

Sorry if the above seemed jumbled or out of order. I know this stuff forward and backward which makes it hard to lay it all out in a linear way in order to teach others.

Oh, I just realised something. If your main drive pulley is off, which can happen on 1st gens as all four bolts are 90° apart, it won't be in the right 'clock position' for you to static time it as described above. There is a procedure for correcting the pulley by finding TDC looking through the spark plug holes, but I won't get into that unless it's necessary.