fuel pump

[kdxkrazy]

I have just rebuilt my 400 sbc and it runs good when its warmed up but when its cold it will idle rough.It seems like its not getting enough gas.ive got a new holley truck avenger on it and the choke opens fully. someone told me it was the fuel pump not supplying enough gas. Ive got a see through filter between the carb and the pump.When I start it, after its set for a while I can see a bubble in the filter that gradually gets smaller and disappears the longer the engine runs. does this sound like he is right or could it be something else?

[roundedline]

A carb motor only needs 5-7lbs of pressure, well within reason for a stock pump.  It isn't getting enough gas because the choke is open when it is cold and it is getting flooded with cold dense air.  The choke should be shut until the engine warms up.  It the choke working properly?

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

[kdxkrazy]

yea, the choke is closed when its cold and opens as the engine warms.

[kdxkrazy]

Ive got an edelbrock performer intake and it does not have the hot exhaust crossover under the carb. Could that be the problem?

[roundedline]

Is it an electric choke or a thermal activated choke?  It sounds like it is working properly.  Unless the motor is warmed up it won't operate properly.

Chris Lucas
www.73-87chevytrucks.com
www.captkaoscustoms.com
Project Su
Jimmy 2WD Project

[kdxkrazy]

its an electric choke.

[RSBAD454]

maybe you need to adjust carb better......plus, does it have a fast idle setting? it will idle like crap until it's warmed up unless a high idle setting is on carb. I don't have a fast idle setting on my holley(my foot is my high idle), the engine won't run well until warmup.

Toys are my game