[Benson]

Quote:

My problem right now is that the engine knocks with very little advancment of the spark. I think my timing is just a little advanced to start with but I hand crank it and it doesn't kick back on me so it can't be real far off. Driving down the road at 30 or so if I advance more than a third down on the lever I get knocking. The car surges ahead as though it wants to be advanced that much but the knocking starts so I back it off. Seems like I'm not able to take advantage of my 5.5 head. I've tried 93 octane with no improvement.

Unquote:

1. When you say the car surges do you mean that it increases smoothly in speed?

2. Or do you mean that the speed changes by itself with the same throttle plate position, the classic definition of surging?

If the engine is surging that indicates a lean carburetor mixture.

Ford originally set up the Zenith jets to be a slightly lean mixture at sea level with the GAV set to the closed position. The idea was that if the car was run at higher altitude the GAV could be set closer to the closed position and if at sea level you could use 1/4 or a little more to get the correct mixture.

The GAV was never intended to be run at the closed position at sea level.

I have run about 50 carbs on an Exhaust Gas Analyzer and no two have the same air to fuel ratio.

But one thing that seems to prevail is that if the mixture is too lean the engine will knock sooner and more often.

If the engine is surging you might try opening the GAV 1/8th turn more than you normally do.

Carb could be plugged up or you might have a fuel line restriction at the sediment bowl or the carb. Or dirty filter in carb or sediment bowl.