68 911L Ignition timing

[jfd]

Still struggling with engine ignition timing.
System consists of MSD ignition sys, with tac adapter, Pertronix, and Blaster coil, all 15 yrs old. Ran fine till recently. Thought it was the distributor, had it rebuilt but still have the problem.
Set static timing at 5deg. BTDC. Turn on engine, will idle (somewhat) around 1200 rpm. Based on 2 different timing lights, the timing signals a flash at approx. 30 degrees advance? Afraid to try setting timing at 6000 rpm.
Not sure what the symptoms are for MSD, Pertronix, and coil failure.

Any help is appreciated

[edmayo]

What happens when you turn the distributor with the engine running showing 30 * advance in a clockwise direction, that should retard the timing back to a lower number, depending on how far you turn it. Then you rev the engine to see if advances the timing.

[jfd]

Thanks for your reply Ed
When I turn the dist. cw the engine dies. When I turn it ccw the 32 deg mark on the crank is 1/2 inch left of TDC on the fan. At 2000 rpm the 32 deg mark is 1/2 inch left of tdc on the fan.

Is the age of my MSD and Pertronix a factor?

Any help is appreciated.

[edmayo]

I don't think you're in basic time, and if I'm guessing right you're loosening the clamp to the case instead of loosening the actual distributor clamp. You will have to start with basics. Remove the intake valve cover on the 1-2-3 side (reuse gasket) Rotate the engine until the TDC mark lines up to the case. Feel #1 intake valve, clearance? If so you're good, if not rotate engine 360* and try again. Now remove distributor cap, look around 5:00 area of distributor body top edge, you are looking for a little notch, that indicates where the rotor tip points when the engine is at TDC and cyl. *1 is going to fire. If the rotor tip is not basically pointing at that notch you are not in basic time. If not use a 13 mm wrench to remove the nut holding the clamp to the case, remove the distributor. Now with a 10mm wrench loosen the clamp around the distributor body, it should now turn freely. You must now install the distributor into the case so that the notch is roughly at 5:00 (when looking down at distributor) and the rotor tip will be pointed at the notch when the distributor is all the way down. Rotate the distributor body as needed to accomplish all this. Now tighten the 13mm wrench nut holding the clamp to the case. Now rotate distributor CW until points are closed, attach your ohm meter leads to both sides of points, you should get a circuit, rotate distributor CCW until the meter indicates open circuit. That is the instant the spark will occur. The rotor should still be pointing at the notch (give or take a couple degrees) Rotate engine until points are fully open, verify correct gap. Put everything back together, pull center coil wire from center of distributor cap, lay 1/8th" from ground, BACK crankshaft up half a turn, now turn crank clockwise slowly with ign. ON at about when TDC mark on pully gets to case mark you should get a spark. You are now in BASIC time. Run engine and use timing light to set timing, with the 10mm bolt clamp loose you can turn the distributor to set timing. Tighten clamp bolt when done.

[jfd]

Hi Ed
Thanks for the very detailed instructions, which I believe I have followed.

Checked to see that No 1 cyl is ready to fire and intake valve has clearance. Set distributor with rotor tip pointing at notch. Starts, idle at 1200 rpm, timing light flashes with 32 deg. mark at TDC. Advance throttle, 32 deg mark moves left of TDC. I am using 15 year old MSD, Tach adapter, Coil and Pertronix. What are the symptoms of these units with age? Should I choose something else to replace?

Thanks for your willingness to help those of us without the knowledge. 84 and I'm still trying to learn.
Any help is appreciated.

[edmayo]

I don't think there is anything I see yet that says your ignition components are bad. Afterall, the engine is running! I do find it interesting that your showing 32 * advance and the idle speed is only 1200. I would think for that much advance the idle speed should be higher. So it sounds like all you need to do now is loosen the 10mm wrench size bolt on the distributor clamp and turn the distributor CW (same way distributor rotates) which will retard your timing to something more correct such as 10* advance at 1000 RPM. As you retard the timing you likely will have to also increase your idle speed settings
so the engine will keep running. Right now it sounds like you are running at least 45* of advance which will kill the engine.
(you only have 3 years on me)

[jfd]

Thanks for the comments.
But... I am still missing something???

Set at 5*BTDC, rotor (tip) set at distrib notch. Start, will idle about 1200 timing light flashes at approx. 30 deg. BTDC . Afraid to try 6000rpm yet? Still with MSD, MSD coil (ohms), and Pertronix. Any help is appreciated.

[edmayo]

Might be your distributor advance springs are broken allowing the advance to easily go full advance. If you turn the rotor in a clockwise direction does it snap back counterclockwise ?

[edmayo]

Look at the I D plate on the distributor and see what you have, might be an S distributor that has a very fast advance curve.