Hi All,

I am about ready to drive my truck off a cliff...that is if the damn thing would run. The truck is a 68 f100 with a 351w c6 automatic. It has a duraspark 2 ignition on it. This all started when I was mid disc brake swap. I was waiting on parts and decided to knock some of the grease off of the engine. I sprayed the engine down with degreaser, let it sit for a while, then hosed everything off. Flash forward a few days, I finish the brakes up and I am ready for the test drive. The truck wouldn't start. Knowing that the truck was running fine before, I figured that i had gotten some water in the distributor. I pulled the cap off and sure enough there was some moisture in there. I dried it out, but still no luck.

So since then I have replaced the pickup coil in the distributor, the ignition module, and the distributor cap. The truck started and ran good enough to go to the end of the street and back. I brought it back and got my timing light out to check the timing. According to the marks on the damper the timing was nowhere near 10* BTDC and it was way advanced. I have tried adjusting the timing (vacuum advance disconnected and line plugged) but it has been all downhill. Now the truck will not idle. I can get it started and it will run at 2000rpm, but if I try to idle the engine down it starts backfiring and dies.

My thinking is that it will run at the high RPM because the mechanical advance in the distributor is advancing the timing enough to keep it alive, then as the engine speed drops the timing is mechanically retarded to the point where the engine won't run.

Overall the timing just seems to be inconsistent. I have never had this much trouble getting an engine to run correctly. If the distributor had points it would be easy enough to turn the engine by had and see when the #1 plug fires, then I would know exactly where the static timing was set. I am not sure how to do that with the duraspark though.

Any advice or tips would be greatly appreciated.

 

Can you elaborate on this? The way you have worded this, it raises a concern that you may have retarded it the amount you thought it should be advanced. Your symptoms seem to be consistent with this.

Reminder: unhook and plug the vacuum advance source while you check timing.

Edit: Also make sure you are on #1 cylinder.

 

Edit out my comments misread the thread?

 

I had just a few minutes to mess with the truck today. When I was checking the timing I did have the vacuum advance disconnected with the vacuum line plugged. I was on the #1 cylinder. The first cylinder on the passenger side.

I pulled the spark plugs out and bumped the starter until I felt pressure on the #1 cylinder. That way I knew I was coming up on compression. I then turned the engine by hand while looking through the sparkplug hole and found TDC. The timing mark on the balancer lined up correctly. The rotor button in the distributor was pointing at the #1 terminal. All good so far.

Now is where things get questionable. I took my old distributor cap and cut a hole in it so that I could watch the rotor as it comes past #1. I hooked the timing light back up and shined it through the "window" in the distributor cap while I was cranking the engine over. When the timing light flashed the rotor was way past the #1 terminal. This makes me think that somehow the reluctor has gotten out of phase with the rotor.

Hopefully I will get a chance to mess with it some more tomorrow.

 

You can set the static timing the same way it's done with points. But wear thick rubber gloves and good rubber soled shoes and make sure the floor's not wet or damp. Ditto for your skin.

 

You were spot on. I worked on the truck a little this afternoon and had no luck at all. It got to the point that it wouldn't even start. I eventually ran the battery down so I put the charger on it and came in for supper. I went out to take the charger off and close up for the night and decided to give it one more shot. I managed to get the engine started and running just enough to where I could turn the distributor both ways to see if it could get it to smooth out. When the truck wouldn't start originally I marked the position of the distributor with a permanent marker. This was the position where the truck last ran, so I was using it as my baseline. I guess when I changed the magnetic pickup in the distributor it shifted the timing quite a bit.

Long story short the timing marks now look correct when I put the timing light on them. I set the timing to ~11 degrees btdc. The truck starts and idles well now. Thanks for the help!

 

Good to hear.