Originally Posted by
1QwkSport2.5r
If you use crankcase pressure, I think you need a regulator or check valve or something to prevent the negative pressure pulse from creating a momentary vacuum in the tank, I think?
Most were on the bottom under the crankshaft port. The port would be open only when the crankcase was under pressure. This produced a lot more pressure than muffler pressure. Most were used for control line and so for wide open throttle only the needle was required, no regulator.