[davidlee]

HELP!!

I have a 351/360hp crate motor prox 300 miles on it.I have a BAD stumble at approx 2100 rpm in 1st gear and the same in second but not as pronounced. The carb is a Holley 750 dbl pumper with mechanical secondaries. I have checked the fuel pressure {6 lbs} checked the float levels{spills out when you shake the car} Increased the jets from the stock 71s to 74s in the front have not messed with the rears. I checked the vacuum 16.5-17.5 at idle prox 20 at on load running on the highway. I have not changed the power valve and assume it is 6.5 from the factory.
This is a consistant stumble and will happen every time I hit prox that rpm level in the lower gears. If I short shift{ stay below 2000} no problem. The timming is set at 38 total. The plugs look like the fuel mixture is ok.
This stumble is sooo bad that my young son has bumped his head on the rear deck several times
I have tried disconnecting the vacuum advance on the dist but it made no differance. The accelator pump is set to squirt fuel as soon as you start to move the throtle.
I need help, this problem is embarassing as people think I am trying to race them every time I take off.
David