I know the 390s are the recommended carbs for the inlines. Is there a specfic model number when buying one?
What trans were you running with the 6?That carb works perfectly on the aftermarket aluminum intakes (Clifford and Offy). I ran one on my Offy for many years. It's better if the carb is mounted sideways as Offy designed it. The two active barrels are parallel to the intake ports instead of two primaries in line with the number 3 intake port, and the secondaries in line with the number 4 intake port.
Here's my L6 that I sold last year with the 4bbl induction. I used to get 18 mpg on the freeway.
Uh, maybe because they all are the same external size? A 390 can look just like a 650, that looks just like a 750, 850, 950, 570, 670, 770............and so on.2 diff buddies said it looks way bigger than a 390cfm