Static distributor timing

I pulled out my distributor to replace the O-ring while I was adjusting my valves. I did not make any marks because I assumed I could use the ones that were already there. I also did not make any measurements of the previous dwell and timing before I took it apart. Now I need some help setting the static timing.

I've turned the engine over to #1 TDC (double-checked that it is indeed #1 using a compression guage). My Bosch distributor has a mark on the body for the #1 cylinder. The distributor mounting flange has marks from where it has been tightened down all these years.

If I keep the distributor turned so that the marks on the mounting flange line up with the bolt, the rotor is either halfway between #1 and #5, or just past #1 on its way to #6, depending on which way I engage the gears.

If the rotor is moving clockwise, I assume you would want the leading edge of the rotor just on the #1 mark, and the bolt in the middle of the mounting flange to give you adjustablility either way.

Is there a more precise way to set this up? Is there a big danger if you get it wrong one way or the other?

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Greg
72 911S

Greg I am doing this from memory while sitting in my office. I have a 72 911E with MFI. Make sure the #1 cylinder (looking at the engine on the left side closest to the rear of car) is on the compression stroke. Line up the pulley marks until you are on TDC. (If you were turning the pulley counter clockwise TDC is the second of the two hash marks in the FIRST set of marks you would come to. The second set of marks is for checking the timing advance.) The distributor has offset gears so to get it to line up with the #1 plug wire (which on my distributor is in the 5 o'clock position) you have to start with the rotor pointed at about the 3 o'clock position. To make sure you have it right just mark where the rotor is pointing and pop the distributor cap on to see if you are pointed at #1. On my car the bolt is only about 1/2" away from the right side of end of adjustment on the mounting flange. If you set the distributor wrong the worst that can happen is the car will not start or just run really bad. Hope this helps.

Kurt V
72 911E

Thanks for the reply Kurt, but I don't think you would ever want to turn the pully counter clockwise.

I just found a photo in the valve adjustment tech article which shows what my distributor position looks like:
http://www.pelicanparts.com/techarticles/911_valve_adjust/911_valve_adjust_pic16.jpg

My engine is at the Z1 TDC mark for cyl #1 (checked w/ compression guage) and the rotor's trailing edge is aligned with the mark on the distributor body. As the engine turns clockwise, the distributor turns clockwise. I would have thought the leading edge would have lined up instead.

Anybody know for sure? Is this picture correct?



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Greg
72 911S

I should have said "imagine you are turning the pulley counter clockwise" just for purposes of determining what set of marks to look for. As for the picture that is definitely the correct position although my distributor is rotated such that there is less of a gap between the bolt and the right edge of the mounting flange. If yours is set up like this you will be close enough to get the car started and be able to finalize the timing.

KurtV
911 E

I kinda thought that's what you meant. :-)

Thanks for the feedback. It must be the right way. If I change the position by one gear tooth either way, it will be far away from the mark.

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Greg
72 911S

Greg,

I believe that pic is of an SC distributor, and they turn counterclockwise, so the leading edge is what you thought was the trailing edge ... in the pic!

It sounds to me like you would want to 'pick' the distributor gear engagement that puts the leaading edge of your rotor between # 5 and #1, and then rotate the body until the leading edge is 'near' the TDC #1 mark on the body. Of course, you will want to verify that the sparkplug lead to #1 is, indeed, in the position marked for #1 in the cap! I have not found that the adjustment clamping bolt is typically in the exact center of the adjustment range, when the timing is correctly set. If you happen to get the timing off badly, when you attempt to start the engine it will either not start or will run very rough and sound 'not normal' ... so you will know immediately if you are close, or not! Have your timing light setup and ready to use when you attempt restart, and the vacuum line hooked up to the retard diaphram. Immediately after starting, assuming it sounds normal, set idle timing at 1000 rpm at 5 degrees After TDC, then let the engine warm up for 10 minutes or so, or until oil temp is 180 before attempting to check and adjust the vacuum 'hose off' timing at 6000 rpm. Run VERY briefly at 6000 rpm, only long enough to see the timing light freeze the mark at the required position, reposition distributor as necessary, then back off the throttle immediately. Good luck!

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Warren Hall
1973 911S Targa