Stumble off idle -

[decooney]

John,

Not knowing your cam and heads and flow, but...based on this info you may be lean on the primary and transition circuit chasing a less tunable situation with that particular carb until doing some additional work on it. I found a few references that indicate the 3310-11 came with 70 or 72 primary jets, a 6.5 power valve, and 76 secondary jets stock. Also, the transition circuit in that carb might be lean too. Some guys run a softer spring on the Vac Sec unit to get it to open quicker too. I ran my FE with 78/78 jets once with a 6.5 pv and it was still lean. I settled on 82/82 squared with 5.0 PVs in my Holley HP carb, and 80/80 is probably more spot on with my particular cam and heads-flow and exhaust setup. ERA sidepipes flow pretty decent. Ran mine 78/78 initially with my original ERA sidepipes until I changed them out for something even more freeflow. Had to jet up again after that.

Before its all said and done, you could end up trying all sorts of different changes with that particular 3310-11 carb and not totally cure the lean spot 100% without some drilling and changes to the metering blocks along with jetting changes, etc. I tried a non-HP standard Holley 750 on my motor once for 15 minutes and it did not run as well as my current Holley HP 830 reconfigured some. Sort of guessing without knowing more about your cam/heads setup. This just based on several other single Holley / FE 428+ setups I've seen guys run.

Do you know anyone near you with a Quick Fuel or Holley HP 830 or HP 850 you could pop on there real quick and try it out before making several changes on your carb?