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Hilborn Primary By-Pass Valve - Brass
 
 
 
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Hilborn Primary By-Pass Valve - BrassHilborn Primary By-Pass Valve - BrassHilborn Primary By-Pass Valve - Brass

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Screw together brass secondary bypass, set at approximately 40 psi. AN 6. Used for main mixture (idle pressure) control. It consists of a body, cap, poppet, spring, jet and seal. It is usually installed in the line that originates at the fuel pump discharge and terminates at the fuel tank. The poppet acts as a check valve to hold pressure for starting and idle.

AN Thread Sizing Guide

 

A .016 wires spring is the most commonly used, however, .020 and .024 are also available. Using a thicker wire spring will give more spring tension, resulting in a richer fuel mixture at idle and low rpm operation. 

The jet (pill) controls the amount of fuel the engine will receive at all rpm ranges. The larger the jet size, the more fuel is allowed to return to the tank, therefore leaning out the mixture. To richen the mixture, use a smaller jet size. To lean the mixtrue, use a larger jet size. 

Drop the jet into the valve so the number is visible to you. This side of the hole has been champfered and is the side that fuel enters. 

Reviews for Item #: 385F510S
Price: $45.99
BRASS HILBORN BYPASS, 40 PSI
Item #:
385F510S
Price:
EA
$45.99

IN STOCK
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