I have a 71 LS6 with a holley 750 double pumper on the stock dual plane 069 intake. All of the plugs that are fed from the low side of the intake are rich and the low side of the intake under the carb is wet. The high side of the intake is dry and the plugs are a perfect tan color. Should i jet the side of the carb(drivers side) with smaller jets to compensate for this rich condition. By upper and lower i am refering to the runners
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Re: Holly carb jetting on dual plane intakes
give it a shot,i would try 4 steps to start and see what the plugs look like. -
Re: Holly carb jetting on dual plane intakes
Jeff:
High side is 1,4,6,7--low side is 2,3,5,8. I would not rejet, because that will just be a "band aid". Your carb has a restriction somewhere. Check your bleeds on top of the air horn. Also make sure you have genuine Holley gaskets installed.
JoeComment
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Re: Holly carb jetting on dual plane intakes
JOE, I have the HP main body that has screw in bleeds and they are brand new as is the rest of the Proform main body (SAME AS HP SERIES, NO CHOKE)Comment
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Re: Holly carb jetting on dual plane intakes
It sounds like you have a Holley 4779C carb, or similar, installed. Go to www.holley.com for any information you may need. I am no expert here, but I am almost positive that the LS6 did not come factory equipped with this manual choke carb. There is no need to have different mainjets for 1,4,6,7----and 2,3,5,8---unless there is an underlying problem somewhere. Look for a vacuum leak, improper gasket (throttle housing-to-metering body), or blockage somewhere- especially in the main air bleed circuit.
JoeComment
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Re: Holly carb jetting on dual plane intakes
sounds like you need to go thru the whole carb and check all the jetting,air bleeds,which size IFR you have and make sure you have the proper throttle plate to main body gaskets.if you used DP holley carb metering bodies you may have to restrict the IFR size because DP carbs are race carbs and they are very rich at idle. you also may have to drill out the PVR to a larger size and go down on the jet size to get a better fuel curve for street drivingComment
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