Plumbers56

I'm running a stock 4.8 with a new 625 cfm street demon carb, looks like a old thermoquad. I can't get this thing to loose the flat/spot, hesitation when I floor it. It doesn't take off right away, a pause then it go's. Also when I go to start it up after being warm it idles at 500 rpm then sits at normal 750 rpm. Fuel pressure? Set at 4.5 psi, bad carb choice? Need help alittle puzzled

ZONES89RS

iTrader: (25)

I would run 6 psi minimum. Otherwise, you probably need a bigger charge of fuel when you stab it. A 31 squirter is doing great on my 86 TA with a cammed 5.3. On my 94 gmc 4.8, stock, I had hesitation, I did not have a larger squirter but did have a 50cc accelerator pump, it worked as well.

newschool72

iTrader: (12)

I think it probably was a bad carb choice, unless you can really step up the tip in fuel charge. LS motors love to injest air (thats why they run so hard) and need a big pump shot when you slam it to the floor.