Holley and MSD experts....HELP!!

Hey,

Have some kind of misfire/fuel feed problem on the racecar....

Specs: MSD 6T box and billet distributor. 15 years old. Holley 390 cfm dbl pumper. Holley electric pump 5 psi fuel feed. Plug wires: all measure 5 to 9 k ohms. Header temps: All over the map from 300 to 500 degrees 3/4" off the flange.

Car won't idle and sounds like it is running on 6 or 7.

Any tips are appreciated.

Thanks in Advance,

Rog

Check the float levels - they may have sunk if they are old enough causing a rich condition. After you've verified that, make sure your plugs are OK. Does that carb have a power valve? Not sure.

What is the base vacuum at idle when running properly?

Take that number and divide it by 2.

Remember that number as XX.

Go to parts store servicing Holley carburetors and say "I need a XX power valve, please. And give me one higher and lower as well"

Ignition: Check the distributor reluctor wheel and, more importantly, the pick up assembly. They tend to corrode--especially with applications that spend time parked, like race cars. Replacement pickup assemblies are readily available and easy to swap. Carburetor: If the gaskets are 15 years old, they have served you well. Time for a rebuild kit. Metering block gaskets, for example, can corrode. The resultant cross passage leaks lead to mystery problems such as the ones you describe.

Hey Steve,

Thanks for the input. Still scratching my head... The reluctor assembly resistance is right where it should be: 590 ohms.

Swapped in the OLD points distributor, car still acts like a major miss on the ignition side.

I'll dig into the carb tomorrow.

Thanks,

Rog

Folks,

Thanlks for all the tips. Problem was a blocked air bleed on one of the primary idle circuits. (One cylinder bank was running too rich to idle.)

BTW: The guys at the Holley tech line diagnosed it on the first try.

Thanks again.

Rog