350 won't start...sometimes!

Other times it starts and runs perfectly.
First time I've posted, but have been helped many times by other threads. Thanks.
I have an '83 Chevy C with an '83 or later 350 V8.
For the last year it's had this intermittent problem, where sometimes it will not start, but I can go out the next day or the next week and it starts right up. Timing light shows no spark when cranking during the no-start times.

Have replaced ign. module, coil, cap & rotor without improving anything. Also checked ignition component wiring and cleaned all the connections. Nothing!
When it runs, it runs really well.
Any suggestions?

Thanks,
Greg

Possibly the ignition switch.

Is the coil housed in the cap on your veh. If yes aftermarket caps are crap and the way the coil makes connection inside is crucial to operation. if yours doesn't house coil I would suspect bad distributor internal coil and poss spark plug wires .you said you checked plug in wires to coil & distrib but did you check B+ feeds. those could be intermittent

Thanks for the replies.

About the ignition switch, I have checked plug going to BAT terminal on distributor cap, and it shows battery voltage when I turn the key. Does that rule out the ignition switch?

Coil is in the cap, but problem is the same with original and with replacement coil in new cap. Have not replaced plug wires.

Is there another B+ feed besides the BAT terminal on the cap?

Greg

Sounds like you have a regular HEI distributor (coil in cap). If you have batt voltage at the dist with the key in the "crank" position (and no start) I think you can rule out the ign sw.

ok the system you have is very reliable but tricky. check the spring activated piece that is suppost to make contact with rotor. if that piece broke or something happened to the spring contact. spark from coil will not reach spark plug wires. I was in advance auto today and happen to see a brand new complete distrib I believe it was $150. Thats a deal. But if you dont know how to pull yours out and reinstall it may be better to check your orig dist.