Lots of possibilities here, and really insufficient information to know what to suggest.
First, as others have suggested, if the adjustment being made is the idle control screw (a pointed screw held in place by a spring screwing into the throttle body [lower casting]) then it makes no change in the mixture at any engine RPM above idle. If the adjustment is a "T-handle" which screws into the bottom of the center section (bowl) at approximately a 45 degree angle, then this effects the mixture at higher RPM's. MOST type 228 carbs do NOT have this adjustment.
Issues could include ignition, fuel delivery, or as simple as the incorrect type 228 carburetor. If the carburetor was designed for a much larger engine (type 228 carbs were used on engines as large as 321 CID) the venturi would be too large, thus flooding the engine with air and a meter would show needing more fuel. The only solution to this issue would be a proper sized carb.
A fuel tank vent was was stopped up could cause the issue. If the tank cannot vent, fuel might trickle out, but in insufficient volume to run at load (up the hill).
A weak fuel pump, or a worn camshaft lobe could not supply sufficient fuel to the carb.
Suggestions:
(1) verify that the carb is the proper size for the engine, else replace the carb. If the carb is the wrong size, nothing is going to help other than the right size carb.
(2) test the fuel pump output (see your shop manual)
(3) replace the fuel filter
(4) try a test run without the fuel tank cap (will test the tank vent)
One other thing: do a compression test to determine the condition of the engine. A badly worn engine WILL lose power on a grade!
Jon.
Last edited by carbking; 10/23/2012 3:19 PM.
