Slight high speed miss

[Standing Elk]

Ok, so my 30 coupe starts very easily and runs smooth until I reach road speed, about 45 mph. At that time it seems to develop a slight miss.I have the more modern points set up installed, timing is set with a light, point gap is set with a dial indicator, spark plug gap is correct and the plugs look good. What should I be checking next? Thanks

 

[Patrick L.]

How does it change with changes in fuel adjustment or spark lever settings ?

 

[Tom Endy]

If you have a modern wireless lower plate installed in the distributor check to see if there is a burn mark on the slider at the position you have the spark advance set to when traveling at 45 mph.

Tom Endy

 

[Standing Elk]

The GAV nor the spark lever position seem to have any effect on it. When I say "slight" miss I mean you really have to pay attention to notice it but it is there.

 

[Standing Elk]

Thanks I will have a look for that. What would cause the burn mark if it is there?

 

[Big hammer]

Loosen your gas cap and go for a drive. I had a slight miss at or above 55, I removed the cap and then no miss, even up to 70, the cruise control then said SO DOWN ! Guess who that was

 

[Patrick L.]

Thanks I will have a look for that. What would cause the burn mark if it is there?

Tom made a great point. The wireless plates are kinda famous for that. They tend to lose contact. A wired plate or adding a wire will correct that.

 

[eagle]

Put some marvel mystery oil in the gas. ATF works too.

 

[30 Closed Cab PU]

Tom made a great point. The wireless plates are kinda famous for that. They tend to lose contact. A wired plate or adding a wire will correct that.

X2. Personal experience, had Nu Rex wireless plates, after a while had some odd issues including the original poster's issue. Spent weeks tracking it down. Tried a jumper for troubleshooting which cured the issues. Went back to non wireless, no more problems.

 

[GRutter]

Check your points. Open them up slightly.

 

[Jacksonlll]

Check ferrule at end of fuel line. Must right at end of tube. Tube hits screen and restricts flow.

 

[chap52]

"Slight high speed miss", same thing my cardiologist told me... HUH!
Couldn't resist... Chap

 

[Jim Brierley]

Close the plug gap slightly, say to .025", and go for a test drive. This will tell you if it a weak spark, or not. I sincerely doubt it is a fuel problem. Good luck!