It may not make one hell of a differnce, but those tubes are supposed to exit WITHIN the air cleaner assembly in order to keep the air pressure on the vent side of the float bowl compensated to any change in resistance of the air cleaner assembly. (That's from Holley's carb book) For instance, if the tubes were outside the air cleaner, any restriction on the air cleaner would act like a choke and increase richness, as air pressure would drop within the air cleaner, but not equally balanced within the float bowl. The tubes being in the air cleaner, pressure drops equally on both the float bowl and above the venturi, and mixture is unchanged, despite air flow being impeded.

Just make them longer and move them away from the venturi opening so that when they spill gas, and they will when you are on a severe slope, it doesn't pour into the venturi and flood the motor. Where will it spill? Inside the air cleaner assembly I guess, and cause a fire hazard. Oh well, can't win when you run a float. Some carbs do seem to be better than others, and out of the box, the holleys work very poorly on hills.

Tim

Man, DUMP THE HOLLEY! unless it says PRO-JECTION!

I did just that on my AMC 360 2 barrel in my CJ 7. I threaded the vent tubes and installes barbed fittings and some hose. Work like a charm. Ain't fuel injection but better than before.

MAN, if u want to help support me gettin PRO-JECTION, then send the money to me, but for right now, i'm a junior at Texas A&M, so i have none, but i like the idea of the extended tubes, but i'm not sure on the pressure thing, because it's only a vent, i don't see how the floats would act different if it lets air in from outside the air filter

I made a tube that comes up out of the front vent, turns aft and then turns down into the back vent. I drilled a set of holes in the top, horizontal section of the tube to do the venting. You have to put a sideways kink in the horizontal section to miss the air cleaner center post.

Stay away from Holley Pro-jection, it'll leave you on the trail some day. We hauled a buddy off Fordyce Creek when his crapped out. he drove home to So-Cal on my carb (I towed my rig home).

fyi, i tried extending the vent tubes on my holley 4bbl (650cfm) and it didn't work so I went to MC2100