I have a 1970 455 rebuilt to w30 automatic specs, with quadrajet etc TH400 and 3.91 posi 10.25CR pistons rebuilt everything.. running 100 octane race gas..

I have checked carb, timing, advance, compression, temp, etc all look good.

Thought it might be water in the gas do to sitting now and then, put in 4 cans of Heat, filled gas tank and ran heck out of it.

overall runs well at all speeds. BUT


when I run freeway speed 65mph about every 2 miles I'll get one misfire, blip, ? for a millisecond then OK go another 2 miles one misfire again.

ideas of what might cause this? annoying

 

loose wire moves at highway speeds, possibly a bad ground. intermentint problems are always the worst.