ok--specifics first. 1979 F-250 400ci C6 sat for a couple years before i picked it up. Has a Holley 4bbl carb (was told it was a double pumper because of the huge float bowls front and back) and supposedly an rv cam. Now, for the important part---

If it idles at 900 rpm, put my foot on the brake, goes to 700 rpm, and when i put it in gear, it drops to 450 rpm, that would indicate a vacuum problem, correct? I dont wanna crank my idle up to 1500rpm just so it dont die under load, so if its not a vacuum problem, is there an adjustment on the carb for this?

When running, the engine has a "pop" sound out of the drivers side bank. Everyone i talk to says sticky valve, my dad just said it sounds electrical. Sometimes it wil blow flames out whats left of the exhaust, sometimes just the popping. If it is a sticky valve, if I run seafoam thru the carb, would it clean the valve, or is that gonna require some tranny fluid in the oil?

How hard is it to rebuild a Holley 4-bbl carb? The truck runs, but has a hesitation, and-in my opinion-has the potential to run better with a cleaned out carb. What do I need to know when buying the kit? any numbers off it?

 

ok...so timing has its fingers in more than i thought....I played with the distributor and the popping went away and it didnt drop as many rpms as usual....crazy fords...

 

Sounds like a plug wire was arcing to another wire. May need a set of wires.

 

wires are brand new....like they have 10 minutes of run time on them....

 

Sounds like a burned exhaust valve. When it fires the fuel/air,it will shoot flames/backfire out the exhaust. Run a compression and leak down test on the engine.

 

still gotta get a compression tester...bought some seafoam, hoping it's just a stuck valve, but the timing is playing into this now, so i dont know.....

 

Dumping some seafoam down your carb or through the brake booster line (if it has power brakes) typically won't hurt anything and might help it run some better. You can put it in your oil too which might help some if you have a stuck valve, it can help free up lifters, etc. If you put it in your fuel, however, be aware that it can cause crud to break loose which will then float on down the line until they clog something up causing it to run worse. As such I really wouldn't do that just yet.

If you have any reason to believe that the timing is not set right, address that first. Seafoam is good stuff, but it can't set your timing, or adjust your carb for you.