Different Pipes need different needle settings:
Have you ever heard someone say?
"Wow I changed from my super duper pipe to the new roger Ramjet pipe and it must get better fuel mileage because I had to lean the engine!" Don't read a lot of meaning into this change, it is all relative to many things the biggest thing is the backpressure differences of the two pipes! More or less is not necessarily better JUST different! More Relative backpressure and you will have to lean or "reduce the orifice size" of the carb, because the extra-pressure will "push" more fuel through the same orifice setting but it may equal the same fuel volume. There are of course other factors, and that new Roger Ramjet pipe MIGHT indeed get better mileage but don't let the Pressure VS needle setting flow rate mislead you!
Good Racing,
-Ron
Rule of thumb:
Longer manifold = more bottom end torque. [At the expense of some rpm]
Shorter manifold = more top end rpm [at the expense of some torque]
BUT you can go to far with either direction causing the engine to run erratic or HOT!
You must keep it in the "sweet spot"
Bottom line: there is no set length for every engine or pipe, experiment with the length to suit your driving style or track needs.
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