Holley Carb problem

First, you need to understand that the idle mixture screws are just that - they only control the mixture at idle. Once the throttle blades are open off idle the idle circuit is out of the picture, so the drive-ability problems are not affected by the idle mixture screws.

Driving fuel mixture is controlled solely by the jets in the metering block, and is augmented by the power valve when required (you open the throttle, the vacuum drops and the power valve opens to richen the mixture).

Float level is also important and can have an effect on the driving mixture.

Your 3310 should be a vacuum secondary carb. Your part throttle hesitation will likely be one of three things - not enough or too much accelerator pump shot, secondaries opening too soon, or a power valve that is not opening.

Out of curiosity, what is your initial and total timing set at? It can have a big affect on drive-ability.

The black smoke during acceleration suggests an overly rich condition, likely the result of too much accelerator pump, or a power valve opening too early.

I would suggest the following;

1 - ensure that the front and rear float levels are set properly. The level should be just at the bottom of the hole in the fuel bowl (your holley will have either a sight glass or brass plug that you remove to check this). If you need instructions on how to set the level, ask and we will help you. Be careful checking it on a running engine as fuel leakage will likely occur and there are sparks going on in the distributor!

2 - ensure that the accelerator pump is working - with the car shut off look down the throat of the carb and open the throttle - there should be a good stream of fuel coming out of the pump discharge nozzle when you open the throttle.

3 - try disconnecting the vacuum pot from the secondaries (or wire them shut) and see if the hesitation goes away.


try these things and let us know what you find.