carb question.

when i stomp the gas in my cutlass at a lower rpm, it stumbles and hesitates, but if i build up engine speed first,  then stomp it, it runs like a scalded dog. my question is do i need a bigger accelerator pump, or a spring kit to get my secondaries in sooner? or am i missing the mark completely and over looking a stupid solution? the carb is a vaccuum secondary 670 demon road demon on a 327, dart heads, .447/.222 cam, 10:1 compression, 4.10 gears, 5 speed manual tranny.  

does it stumble when you pull away from any stop?????

since the secondaries are opened by vacuum.. they should not be opening when you tromp on it.. until the vacuum comes up..

i am going to say...

bigger pump nozzles..

different pump cam setting or different pump cam...

both of these are easy to do.. without removing the float bowls.. easy to change back..

holley has a you tube site with videos that cover your exact problem..

why look at holley youtube.. its the same design carb.. just different manufacturers...  

a few links...

http://www.youtube.com/watch?v=k-Nx5HEzvlY


http://www.youtube.com/watch?v=k2-RY2JqWek  

thanks wayne, doesnt stumble from a stop, only when i floor it at a lower rpm. thanks for your help  

im going to fool around with different squirter sizes when i get a chance and let you know what i find.  

Try adjusting the accelerator pump.  



Professional Hi-performance engine builder

thats the plan, im going to follow that video wayne sent, and adjust the accelerator pump, and then play with the squirters, and acc. pump cams. thanks pman.  

I don't know much about Holleys but have lots of experience with other carbs and that sounds like a vacuum secondary adjustment is needed. The gulp its getting when you dump it is either too rich or too lean, or not on time. If the pump adjustment doesn't work, maybe look into that.  

will do junkman, thanks for the advice.  

went home over the weekend and fooled with the carb, i adjusted the acc pump, but at .015 like the video said when you snap the throttle it hesistates, you can hear the engine pull more air but just hesitates, when the pump arm clearance is tightened a little but more the response is snappy and doesnt bog. is my next step a larger numbered squiter?  

Olds, the plastic cam that actuates the the accelerator lever has several positions for the small screws to go in.,. try advancing the cam into the lever.
There are several different color cams you can get and each one has a different rate of actuating the pump.  
When The Flag Drops,,,



The Bull Chit Stops,,,

P. Engineer.,. Engine Builder

alright, ill try the #2 setting on the cam, i rewatched waynes video before posting and it said to try different squirters before cams, but i cant figure out which way to go bigger or small, both symptoms for lean or rich conditions are similar, plus they reference heavy v. light cars, i dont know what mine is considered, its probably about 3200 without me. thanks tuff by the way  

Your car would be considered light and you'll have experiment and keep tweaking, but do only one thing at a time or you'll get balled up.  
When The Flag Drops,,,



The Bull Chit Stops,,,

P. Engineer.,. Engine Builder

i figured it would be a middle weight car. i understand the step by step approach, but the question is where to start. should i follow waynes video or experiment with cams first  

Hi there Agent 85,
 You would be best suited to try the cams
 1st as the cam will slow or quicken the actuation
 of the fuel delivery..You might try wearing lighter
 shoes as well.          
skyeking