Surging while cruising at steady speed. Idle and acceleration great, Help!
The surging doesn't seem to effect engine rpm at all, just feels like its missing basically but I really don't see how it could be ignition related because everything has been checked.
Timing and fuel mixture are a hand in glove relationship. For now, lets see about getting the fueling to go with the timing. If changes have no effect, then going to have to look at timing.
That makes sense about the idle circuit. My idle air bleeds are 70/70 according to my Quick fuel carb card. Not really sure what that means. .. so that probably means .070/.070 right which means I should try the .067's?
You got it. Unlike Holley Jet sizes which are numbered based on flow, air bleeds are numbered strictly on diameter. Yes I think .067 or .068" would be the next step to try. 069 is too similar to what you have. Or, if its quicker and easier, stick some wires in for now. Then depending on the results, buy a pair the sizes that are close and fine tune. If you're just tuning this one or two carbs, an assortant of sizes on hand rather than a lot of one seems to make more sense to me.
The air bleeds reduce the pressure difference driving the fuel. Fuel pressure in the bowl is bascially atmospheric, and fuel in the idle circuit flows toward the low pressure we describe as manifold vacuum. An air bleed reduces that pressure difference.
For idle circuit, its generally true that larger air bleed will make the fuel to both the idle port and transfer slot leaner, and taper off earlier.
Main circuit can not be so simply generalized, but if the fuel mix goes leaner or richer as the engine approaches redline, it generally relates to the air bleed sizes.
