I have a 1965 F150 with a 300 cid straight six, manual 3 on the tree. I think I may have a carburetor problem, it is original and it looks like the previous owner fiddled with it (darn). Timing looks good, vacuum is near zero at idle but erratic when I hand manipulate the throttle. It starts and idles fine, but when I get it on the road it keeps stalling. I have to restart it several times, usually just after I take my foot off the gas.

Any troubleshooting suggestions?
Paul

 

Vacuum is near zero at idle? Where are you checking the vacuum? It should be ~20".

First thing I'd try is a new fuel filter.

 

Exactly, the book says 17-19". I took the line off near the carb where it comes out for vacuum advance.
I was thinking about the fuel filter. The original one that attaches to the carb is missing and the previous enthusiast goobered it up with JBweld (no filter) and a fitting that, of course, doesn't fit the NAPA replacement.

 

There is little or no vacuum on a timed vacuum port. One has to tap into a full manifold vacuum source.

 

Oops. Thanks, I'll put it on the base port and read it again.
Paul

 

Welcome to the forum, Plundy!

These engines do not like vacuum leaks! Check all vacuum lines [distributor, PCV valve and power brake booster]. Also, check the two nuts which hold the carburetor to the manifold as they tend to loosen due to engine vibration.

 

Thanks, when I first started on it the carb was squirting gas. I gently tightened the already mangled float housing screws to stop it. I'll go back and check the carb to manifold nuts. I'll look to see if there are any other vac leaks. I replaced the vac tubing to the vacuum advance since it was a bit cracked.
It looks like the only fuel filter is the one on top of the fuel pump. I'll pull it and visit the parts store. Not sure what number it is.
Paul

 

I changed the fuel filter, snugged the carb mounting bolts and tightened the vacuum advance connection which wiggled a bit before tightening. I took the vacuum reading straight off the intake manifold, and behold the vacuum was 18-19 inches at idle.
It is still stalling on the road.

 

Finally checked the timing... it was 14 degrees TDC! I put it back to 4 degrees and now it only stalls occasionally.

 

A 65 F150 would be a pretty rare truck since they didn't come out with the F150 for 10 more years,lol. Did you check the screws where the base of the carb attaches to the float bowl? I've seen those work loose.

 

Yep, pretty worn from the previous back yard mechanic.

 

if you're new to the '65, you may want to read this:
Classic Inlines Ford Six Load-O-Matic Distributor & Spark Control Valve

the stock configuration would have been a load-o-matic carb & distributor. lots of people don't aren't familiar enough to know that these pieces are a matched set- you can't change one without changing the other. make sure your setup isn't mis-matched.

 

Excellent article, I will try it using manifold vacuum and see what it does.