Confused

[Countryboy432]

1985 Ford F250 460 stock holley/motorcraft 4180 carb.
Truck starts fine and idles fine.
Once I get up to freeway speeds the problems start and even remain after I get off freeway and am driving back roads. At cruise speed things seem ok. When I give it gas it hesitates and bogs down with a loss of power like its not getting enough fuel. However I have ruled out a fuel issue. Carb is getting plenty of fuel. Problem seems worse if truck warms up past the center line on the gauge also. I am wondering if its a timing issue and with the vacuum advance dropping out as I hit the throttle am I retarding the timing too much? Carb is old and has never been rebuilt so that could also be the issue .... perhaps needs a rebuild. But I don't wanna blame the carb without ruling out other issues first. HELP PLEASE

 

[Fellro]

I would be searching for vacuum leaks first and foremost. It may be one that is through one of the temperature vacuum switches.

 

[Dirky]

Your carb has a restriction somewhere, rust particle or other foreign debris.



You say that your carb has never been rebuilt? Dead give away, I rebuilt a 650 Holley with the same symptoms. It was DIRTY inside, as if it had been sitting behind a shed for a couple years.

Derek.

 

[Countryboy432]

You're probably right .... but I wanted to rule out everything else before blaming the carb. I also had to replace the water outlet (thermostat housing) and in the process I eliminated the top temp vac sensor that the vac advance for the distributor runs from. The stock setup had the sensor running off the manifold vacuum nipple on the intake manifold ... not even connected to the carb at all. So my quandary now is should I run the dizzy vac advance off the same manifold vac nipple or off the carb vac port that is actually set up for the vac advance? Not to start another big debate on ported vs manifold vacuum .... the nipple on the carb I speak of is located below the throttle plate right next to the PCV valve vac nipple. It is not full manifold vacuum like the nipple on the manifold however. It has no vac (or very very little) at idle and increases as the throttle opens. However it is what Holley indicates is supposed to be used for the dizzy vac advance. I should mention that I am in California so I have all that SMOG crap to deal with and YES its still stock on the truck. I also have the Holley/Motorcraft 4180c carb. Needless to say I am still a bit confused. I thought the port on the carb below the throttle plate was the same as manifold vacuum of the manifold nipple. So now where to hook up the vac advance. Once this is worked out I will order the carb rebuild kit and get to work on that part of the issue. Thanks in advance for any help you'all can give.