Tuning Holley Carb for New Head

[200ci66]

66 Block with a 79 250 Granada head milled .060".The intake is milled down for the direct 2bbl mount (size of the hole on the intake is the size of the base of the carb) for my Holley 5200.

Had a problem concerning the size of the pushrods but got that fixed with spacers. Now I'm having trouble with throttle response. I assume that my car is either running rich or lean due to the fact that the carb is mounted differently. When changing the Holley 5200 from the adapter to directly mounted, would I put richer jets or leaner jets in assuming that I liked the jetting before I made the change? I would think that since it's directly mounted it's putting in more fuel, but could it be that the jets are too lean for how the carb is mounted? I don't know which direction to start in. Anyone have any suggestions on what size jets I should start with?

 

[bubba22349]

With the direct mount the carb should have a stronger signal but Without using an exhaust gas analyzer of some type you would need to put.a fresh set of plugs and tune it then drive it and read the color of the plugs to be able tell if you lean or rich. Also have you rechecked your float setting, looked for any vacuum leaks at carb base, and retuned the idle speed?

 

[200ci66]

I don't believe there any vacuum leaks. Floats alright.I have put in a fresh set of plugs and I can't tell. They dont appear especially dark or light. Any size jets anyone would recommend starting with and working from?

 

[170-3tree]

Figure out what jets you have then move down two sizes. Stronger signal for carb generally means it's richer. IIRC

Then there is the distributor curve issue if that hasn't been addressed yet, do it.