[eschaider]

You want to be careful about using reduced fuel pressure to tune the engine, Al. The reduced fuel pressure will have no effect until the engine is at peak power where the reduced fuel pressure will be inadequate to properly fill the float bowls.

To produce a lean effect the float bowl fuel level will need to fall below the office your main jet which will produce a sharp reduction in fuel at peak engine power. This type of unmanageable stoppage in fuel delivery at peak engine power does permanent damage to pistons and rings. It would be decidedly to your advantage to have the engine tuned under controlled conditions like you can produce on a chassis dyne.

Although some people may use dyne sessions to optimize peak engine power, you are generally better served using them to maintain a consistent air fuel ratio across your engine's operating range. While you can do this with a Wideband oxygen sensor and street tuning it is both not as good nor as repeatable as the steady state environment you can produce on a chassis dyne.

All carbs have changeable jets and power valves. Depending on how closely matched to your engine's appetite the carb is out of the box you might need to change emulsion tubes and air bleeds to match the fuel delivery to the engine's appetite for fuel. When you are finished you will be quite pleased with the engine's driving personality.

Parting thought; Modern pump gas with a 10% ethanol adder does not have a stoichiometric ratio of 14.7, the addition of the ethanol moves the stoic point to 14.08 for a 10% ethanol blend. The actual ethanol in pump fuels can move around a bit so always assume you have at least 10% and tune to the 14.08 Stoich point. Your engine will be safer and run better.

BTW the old saw lean is mean is just foolish. Lean will cost you parts. Properly fueled will produce repeatable, dependable engine performance.


Ed