[VintageMusclecar]

Jeff;

Several things could be causing your problem. The very first thing to check is your ignition timing. Once you've verified that's in spec, proceed to the carb.

Your carburetor should be set up as follows:

70 primary jets

76 secondary jets

8.5 power valves front & rear

White "218" pump cam (screw in the #1 hole should be fine)

.025 squirter

To adjust the accellerator pump arm, make sure the choke is completely "off" and the primary throttle shaft is resting on the curb idle speed screw. Tighten the adjusting screw just until there is some slack in the linkage, then loosen it just until the slack is taken up. The pump lever (underneath the float bowl) should start to move immediately as the throttle is opened.

Next, verify you're getting a good pump shot through the squirters by slightly opening the throttle (engine off of course) and watching for 2 steady streams of fuel coming from the squirter.

As far as the secondaries go, the secondary stop screw should be keeping them just barely open.

Lastly, check the primary throttle shaft for excessive play as Rick mentioned above. If it is excessively worn, it can cause a lean condition which can cause a tip-in stumble.

There are also a few other possibilities that lie inside the carburetor as well; if the main body is warped badly enough, it can cause a poor gasket seal at the accellerator pump transfer port (just above the power valve cavity) which can allow fuel to bleed out of the pump passage into the power valve cavity, or there may be a corrosion issue inside the pump cavity on the bottom of the float bowl.

If you can't pinpoint the issue, give me a call if you'd like and I'll try to help you through it.

Eric