Yah bill I would start with the basics. Fuel pressure and float level plays a major deciding factor in a boosted application on your afr. And with you adding the vent tube extension there even more air or force in a direct path of the fuel bowl cavityI pushing down on the float. I can't believe you need more main jet im half tempted to send you my 650
On the 650 I have 72 main with 1/16 prvc and 82 with 1/16 prvc in the rear and it stayed pretty consistent at 11.0 into boost without vent tube extension
Bill next time you have the metering block off take a numbered drill bit and take note of the prvc size that has a direct relationship with main jet size when I'm building a carb I always open mine up to 1/16 inch to start with and I haven't had to go any bigger
Start there bill and if you want I can clean up the 650 and box it up and send to you just a thought
Spring is here even though the temps don't show it
Aaron
