Was it running fine, then didn't anymore? Has this been the new normal since you "had the heads done" and reassembled the engine, including maybe removal and reinstallation of the distributor? Or something else?
Simple fouled plugs can cause a lot of grief and make it tough to figure out the condition of the ignition system, carb/carb tuning, proper timing, etc. foul or wet the plugs bad, like when it won't start for some reason & especially when the engine won't run long enough to heat the plugs until clean- and it's bad like a valve float that will occur at an ever lower rpm if you keep flogging the engine. What happens when you Change the plugs for dry ones- new, bead lasted, propane torched, whatever.- ?? Short drives or run periods in cool weather with an FE can be a quick path to fouled plugs.
a slipped balancer has nothing to do with the actual timing or phasing of the crankshaft to camshaft. It simply has marks to help externally indicate that phasing when it is in the proper assembled position. Check your static timing, approximate it by watching the valve action and compare it to the distributor (rotor position) and balancer (timing marks). Regardless, the position of the rotor/distributor in relation to the tdc of #1 trumps the marks on the balancer. Go from there.
Maybe the carb needs work. Maybe the gas is crap. Maybe they're both fine. Same with the vacuum advance, petronix. Maybe the dist cap rotor contacts (like inside an old cap) are all corroded and only allowing a weak spark so they need to be scraped clean and shiny again so the plugs won't foul quickly from a weak spark
Adequate spark, fuel & compression in proper timing. That's all there is. There's a lot of things that might be contributing to the problem(s)- alone or together- but it's hard to know unless the whole situation is clear.
When you don't know or it isn't making sense, Turn one screw or change one part at a time. When that action makes no difference, undo that action before moving on to the next part or screw.
1967 Galaxie 500 Red original Q code 428
1967 Galaxie 500 White with Black stripes 428PI clone- car is dead & long gone, sold near Oak Ridge TN 2000, would love to find it.....
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