spark, working, not working

[davehdicus]

my 1969 F-250 390cid. Runs good till it warms a little then no spark . wait an hour starts drive to store drive around town parkiy. go out next morn fires right up, idles a few min. than dies, check no spark. new coil, dist. parts. voltage reg, start relay. the only thing I havent changed is the alt. have a new one just havent tried it yet. nww wirs from ign. switch. , perplexed???

[duaneo]

I don't have any firm advice, but my ignition issues were due to the condenser grounding out. I am visualizing a situation where a wire changing in shape a little when it changes in temperature. Take a look under your distributor cap to make sure nothing is shorting out and effectively causing the points to be bypassed.

Also, for what it was worth, I was turning my engine over in the dark, which made it easy to see the spark, or lack thereof when I pulled a plug wire loose.

Cheers,
Duane

[fordman]

Check power going to coil when this happens. Could be loose ignition switch too.