I have the gmpp 350/330 engine. which has vortec heads cam with lift .435\.460 and duration @ .050 of 212/222. I have the 4160 holley 600 vs. which has a mild stumble at throttle opening from a stop or from a roll. air fuel gauge shows around 14 @ idle, cruise, wot but leans out clear off the scale when you step on the gas (which should be normal) but it takes a while to recover. I have a .031 nozzle with a 30cc pump and the red pump cam. I ordered a .035 nozzle and a pump cam kit with plans of putting the blue cam in the #2 hole. I ordered the nozzle just in case i need it. they should arrive by the end of the week.
Any opinions on if i am heading in the right direction? should I need to go with a .035 nozzle on such a mild setup?





If it matters I have 3.73 gears, 700r4 with 2400 stall and shift kit

 

Assuming your primary jetting is okay, what you need is a higher number power valve.

 

That was the other thing i was wondering??? It has a 65 in it now. I know the engine has about 14" of vacum @idle but not sure what it has @cruise. I need to figure that out yet. The jetting seems fine. the plugs have a tan color to them. And the air fuel gauge is staying right around 14 to 13 @ idle cruise and wot. I have been told 14.7 for fuel economy and 13 for best power. so that should be fine.

 

changed the pump cam and it made a big difference. Then change to a .035 nozzle and bumped the timing up to 12 btdc and it REALLY liked that. I am looking at the power valve next. soon as it stops raining around here i am going to hook up a vacuum gauge and go drive