Ok, last night i raced a 94 Mustang V6. Needless to say i beat him, but not by nearly as much as I should have. I got maybe 2 carlengths but no more. My diagnosis is that the secondaries on my carburetor are not opening up. How do I determine when and under what load they will open? Can i do this when the car is parked?

I know i need the secondary spring kit from holley, but what is the exact procedure to determine which spring is correct for the application?

Also, that 4th biotch of a screw on the Holley carb, how does it come off? Thanks.

 

I hope you have the quick-change secondary spring conversion on your carb. Because what you want to do is put in a progressively lighter spring until it bogs when nailed to WOT, then put one spring heavier back in.

Get the quick-change conversion (if you don't already have it) and a spring assortment. Then go have some fun. I got the carb, conversion, and assortment in the same box from Summit, so I don't remember which part had the chart, but Holley has a table that shows what RPM you can expect the secondaries to start and complete opening based on spring used and engine size (approximate, of course).

If you have a 4160-model carb, you might want to get the 4150 conversion and jet assortment kit while you're at it.

BTW, the only way to do this while parked is if the car is "parked" on a chassis dyno.

 

I think this might actually have been my answer. I discovered it today when i changed my ignition wires.
right here