I"m gonna post this question on a coupla Forums. I know there are some really good carb guys out there. So heres the story. Holly 4000 teapot that stumbles off acceleration. I know these carbs really well (apparently not well enough) so I have addressed all the usual items. Float level is adjusted properly,fuel level is correct. It starts and runs with no problem. It goes like hell if you mash it to the floor. Its just got this off idle hesitation on normal gas pedal pressure. The pump shot is slow on accelearation. I have replaced the accelerator pump and rod assembly (twice). There is a pump discharge needle that I have discovered comes in some different lengths and weights. I have tried different pump discharge needles with no success. The pump link lever is positioned in the short hole allowing for an immeadent and longer pump shot. I have a good pump shot but its not immeadent enough. Could this be the butterflys opening before the pump shot? My question is "Is there anyway to hasten up the pump shot" ? Thanks to all. Oldmics
I'm no expert on the Holley teapot, but it seems like most carbs have some way to adjust things so that the pump has a bit more "preload". This would put the pump plunger slightly further down in the pump bore with the throttle plates closed at idle. Maybe try straightening the rod a little that connects the lever on the throttle shaft with the lever that moves the pump plunger. You may just have to study all the linkage involved to see how it works. Of course you don't want to over-adjust it to the point where it wants to bottom out the plunger in the pump bore. You mentioned the pump discharge needle but what about a ball or check valve used on the fuel inlet side of the accelerator pump? Is the check ball clean and smooth, the right size, is there a spring required to help seat the ball or check valve?
Sounds more like a tiny passage that is partially blocked did you blow them all out or run some tag wire through them when you went through it?
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