<VV> Jet sizes

[Grant]

 "I've already noticed an improvement in drivability with .053 -.054 jets in some street applications. The engines need for fuel because of fewer BTU's available with ethanol. Sadly, this all means less MPG's"

I have been stalling one size over stock in my carbs for about 10 years now with good results. 1964 carbs need .053" jets because of the larger engine and absence of the enrichment circuits. Some 140 secondary carbs came with .046" jets, and that just doesn't work with the current fuels. .049" is probably the minimum you need in them. Same deal with YH carbs - should go up a size or two after 1963. 
Grant