53' F-100 with a 239 flat head 8. When I first got the truck a year ago, a guy came over and showed me how to set the points. We set the points gap at .015 and the timing. The truck fired up.

Later another guy came with a dwell meter. We set the idle speed and set the dwell as close to 28 degrees as we could get & adjusted the timing. I've been running with that but over the weekend...

Found the points gap to be less than .005. Also discovered (through reading past posts) the relationship between the gap and dwell.

I went ahead and set the gap back to .015 and reset the timing. That sent the dwell down to 14 degrees.

The truck runs fine with both settings. I'll see 'bout the mpg after these adjustments.

Which should I trust. The meter or the feeler?

Howie

 

My understanding on the matter is the recommended point gap is approximately what you would have with the corect dwell angle being set. Theroetically, both numbers will be within spec at the same time. That assumes one is operating the feeler gauge properly and your meter is functioning correctly. To have the points closed that far tells me your meter isn't right, if you're working the feeler correctly. ;-)

 

On my old dwell meter, you have to double the readings for either 4 or 8 cylinders, I don't remember which, but that would make the 14 deg = 28, right? Suspicious. I would want the 0.015" gap for sure, otherwise it will really arc a lot. Are you using a good points lube on the cam? Any chance the rubbing block wore that much to reduce gap to 0.005"?

 

I think Ross got it right. I learned at an early age to apply point grease, otherwise the rubbing block will wear rapidly and soon you will have too little gap which equates to too much dwell.

I think dwell is more accurate as you can see a number. Gap is kind of a feel thing and is subjective.

 

Thanks much for the advice. I did put lube on but don't know the history of the distributor prior to getting the truck.

Howie

 

I asked my local NAPA parts guy if he had any special points grease. He told me to just use regular grease. Is he right, or do they make a special grease for the points?

 

used to be a special grease.. didn't pick up dust

sam

 

It is special; it's high temperature, very waxy. Filko makes the most popular. AutoZone sells little packets at the counter, called "bulb grease", that appears to be something very similar. I've heard it is getting very hard to find. Regular chassis grease will get thrown onto the points.