PA Dodger
Well-Known Member
I'll start this thread by saying-Yes I did search, and research this issue.
My 340 has a problem with the idle being overly rich at idle. The carb is a 650 cfm mech secondary Holley. The car runs really well but has always been rich at idle. I rebuilt the carb and still have the same problem.
The stats: timing is 20* at idle/car idles at 900 when warm/vacuum is 10ish at idle/PV is 6.5/idle mixture screws are 1 1/2 turns/primaries are set "square" on the transition slot/secondaries are set per the Holley rebuild specs/cam is .485" lift-220* [email protected] -266*duration-110-104 LSA.
I read where opening the secondary butterflies will help this condition. When I opened the secondaries a half turn I had to back the primaries down to get the idle back to normal. My primaries were already OK to the transition slot I should have been OK running off the idle circuit. It seemed to help the rich idle but I don't understand how. What I added to the secondaries I took away from the primaries. Is this the same thing as drilling the primary blades?
Any other suggestions? Vaccuum secondary carb? smaller carb?
My 340 has a problem with the idle being overly rich at idle. The carb is a 650 cfm mech secondary Holley. The car runs really well but has always been rich at idle. I rebuilt the carb and still have the same problem.
The stats: timing is 20* at idle/car idles at 900 when warm/vacuum is 10ish at idle/PV is 6.5/idle mixture screws are 1 1/2 turns/primaries are set "square" on the transition slot/secondaries are set per the Holley rebuild specs/cam is .485" lift-220* [email protected] -266*duration-110-104 LSA.
I read where opening the secondary butterflies will help this condition. When I opened the secondaries a half turn I had to back the primaries down to get the idle back to normal. My primaries were already OK to the transition slot I should have been OK running off the idle circuit. It seemed to help the rich idle but I don't understand how. What I added to the secondaries I took away from the primaries. Is this the same thing as drilling the primary blades?
Any other suggestions? Vaccuum secondary carb? smaller carb?