Ignition or Carburetor

[TommyClocks]

I did some more troubleshooting tonight. I connected a fuel pressure gauge just before the fuel line goes into the carb. I conected a volt meter to the power source to the fuel pump. I set the meter on peak hold negative. The pressure gauge read 2 - 2.5 lbs while it ran, and didn't change when it stalled. The fuel filter still had plenty of fuel in it. How much fuel pressure do these cars like? Maybe 2.5 lbs is too low, I couldn't find specs in any of the books I have. There is a fuel regulator with a glass bowl before carb, I haven't tried to adjust that yet. The voltmeter connected to the fuel pump read 11.5 volts after the motor stalled.

I was able to reduce the ignition timing to 12 degrees BTDC while it was still idling. I noticed that the timing light went dark just before it stalled, still sounds like an ignition problem. I also noticed that the pointer on the crankshaft jumps erratically while the motor is idling, while shining the timing light at it. It seems to jump intemittantly about 10 degrees in either direction. I had a spare coil wire and tried it, but it didn't change the symtoms.

I'm not sure how to answer the question about compression. I don't know how to raise compression without tearing down the motor and freshening it up. I could try those oil additives to help seal the rings, but they seem to cause problems too.

This is a good one....time for a shot and a beer.......

[rasouth]

I just went through a similar problem after re-doing my head. I traced it to a loose wire coming from one of my points. As the motor vibrated or I adjusted the dist the wires would come loose, therefore stalling the engine or making it run rough. Check wire connections and ground connections.

[TommyClocks]

So far I have replaced the wiring from hot to coil, and from coil to points. I have even added a ground wire to the ditributor body in the off chance that I lose dist ground when the motor gets hot. I have a single point setup, the duals were removed before I bought the car, so it should be fairly simple. I have a timing belt and tensioning pulley on order. Ron and I found that the timing belt seemed loose when we compared it to the belt on his car.

[TommyClocks]

I am happy to report that I found the problem last night. I replaced the distributor cap and rotor. The motor started fine, warmed up and ran for more than 25 minutes. The idle was really smooth too, not a single miss. The distributor cap that caused the problem was only about 9 months old but md88plt called it right. That you for that advice, I may not have chosen the cap as a possibility because it was relatively new. The cap showed no cracks or any obvious problem but as it heated up, it failed.

I took the Spider out for a road test tonight and the car had more power than I remember it ever having. Imagine climbing a hill on the freeway and not having to downshift to 4th. Maybe the carb that I rebuilt helped the performance a little also. I received a new timing belt and pulley today, I think I may want to tackle that next weekend. This weekend I think I want to burn some dead dinosaurs and put some miles on the Spider. Anyone local who wants drop by for a timing belt party? I'll make sure I have gas in the BBQ grille.

Thanks to all who sent advice to help with this problem, this really is a great group and a very informative forum.

Tom