Re: Rick S,Thanks for answering my questions,i have a couple more for you.

Mark,

I run 92 pump gas for the most part...that's as good as it gets around here. I had a barrel of 100 unleaded in the shop and it always seemed to run a little better with a couple gallons mixed in. I can't say that I have experienced any of the 'choppy sounds' you mentioned. I bought my carb on the Bay from a guy who had it on a pretty ratty Mopar 440 very briefly. He explained something similar you have mentioned and he never got it running very well. The carb is a custom job intended for his application but it seems to work pretty well on my 521, maybe it's my smallish cam. I am no carb expert, but I feel Dave McLain has nailed it as a transitional problem. It would be nice to have it on the dyno and see where your A/F ratio is at between 1800-2500rpm. Give his idea a try, at least you are not changing the carb permanently and it will give you an idea of if you are too rich or lean in the transition.

Rick