tokinGLX

i recently put a holley 650cfm dp on, at first everything seemed fine, idle ok, started and ran no problem. but after driving for a chunk of minutes, it will sputter, usually when i get above 2500 rpm(tho not everytime, and occasionally well before). at this point, if i step on the gas pedal, the engine struggles to keep going, a constant sputtering.

if i am going down hill i can give it a very slight bit of gas and it will stabilize and return to normal function, usually i have to shift into neutral, when doing so it dies completely, then pop the clutch, it starts right up and off i go.

if im going uphill when it sputters out, i have to pull off the road, let it sit for a minute and it starts up like normal.

the previous carb on the car was an edelbrock 600 with an electric choke. the holley is a manual choke that i have not hooked up yet. i dont have a fuel pressure gauge. the fuel pump is a mechanical, do i maybe need to get an in tank pump as well¿

Grimace5.0

It went from good to bad just by changing the carb? Or have you changed other parts at the same time? Just trying to figure out the situation and try to help you.

1st I'd check the float level
2nd I'd check the fuel filter
3rd I'd check the fuel pressure

Let us know

vfast

I think it's the float..also that 650 dp is a big carb..also you might want to do some jet down sizing if you have a big cam then maybe you need a different power valve

86gt5.0HO

I'd put a smaller carb on it (500CFM). You will prolly like it, it will give better throttle response and low end torque. Also if you have the old carb check what jet size was used and put the same size in the new carb.

tokinGLX

thanks for all the input. first, yes, just the carb. the main reason i got this carb is that i plan on getting a new set of cylinder heads, soon after that either a turbo or blower. been going back and forth between the 2 for months.
its got a mild cam in it now

im reading how to check the float on the holley site (http://www.holley.com/data/TechServi...Carburetor.pdf) ...any other info or pointers¿

tokinGLX

i checked the float level on both sides, it is where it is supposed to be at, took the car out for a drive, and its still doing the same thing. should i just pay to take it to a shop and have them tune it¿ im a complete novice when it comes to this. if so, does anybody know of a decent shop in the denver area¿

5.0coupe

u might have some carbon build up also