79 310 cutting out

[datx]

Hello, I have a 79 310 that I have been working on-and-off for over a year. Thought I had everything running good but now it cuts out when I go above 45 mph. It is not consistent. Sometimes it will run good a little longer than others. Drop the speed back and it runs fine after a little recovery time at the lower speed. I replaced the fuel filter and even thought it may be a vacuum issue in the gas tank but I tried running with no gas cap (thinking that may help) but it does not. Any recommendations would be appreciated. I am no mechanic this car is my first automotive project. Is there an adjustment I should try on the carb? thanks

[metalmonkey47]

What engine is it?

 

You might be having a problem with the vac controlled secondaries.

[datzenmike]

Running out of gas by the sound of it. 45 wouldn't be fast enough for the secondaries I would think. You have changed the filter which is the most likely cause. Check the sight glass on the front of the carb when running, is it near the mark on the glass? If not showing the float may need to be adjusted up to raise the fuel level.

 

OR:

 

Lets assume the level is good, so take for a drive somewhere where it's safe to pull over to the side. Drive it hard until it starts to cut out and shut it off quickly and get it out of gear immediately and I mean as soon as you can. Carefully pull off the road and check the fuel level in the sight glass. I'm betting it will be empty.