Not Ranked
The tuning of the carb is based on a lot of factors. A good way to start is with the carb as it came from Holley. After your first start and cam break-in I usually set the float levels, idle speeds both the fast idle cam and the idle screws, then the idle mixture for max manifold vacuum. Take the vacuum in inches of mercury (in hg) and subtract approximately 2 from it and that is the number power valve you need (I run between 10.5 and 11 in hg so I use 8.5 power valves). However vacuum can vary significantly with your engine build, caused mostly by the cam, so it is very important that you take this measurement. The power valve selection has a big impact on and low rpm driveability/power.
I would install the power valve blowout preventer check valves at this time if your carbs don't have them.
The jet selection is a bit more subjective unless you have your exhaust gas measured during a Dyno run. I check plugs and exhaust pipe color and make changes accordingly.
Mine runs best with #58's in the front carb and #60's in the rear carb ( the front half of the engine runs a little cooler than the back half). If I lived in a cooler climate I would drop down another jet size or two but as I live in Alabama where 90 plus degree days are common it is safer to run on the slightly rich side.
Hope this helps, Keith
|