theory

so the back ground is carb operation

they are mfg with tolerances to compensate for metal expansion and shrinking--not rocket science

they were designed based on a fuel that has been made to use fuel that evaporated much slower than what is available today

therefore, would it make sense that tolerances approaching the former mid to max limits would now not be acceptable to operate

my guess is that a fuel that evaporates quicker must be lighter and or thinner, which would magnify the allowable tolerances

and yes i am still jacking with the 300 6---i think i will say that carter yf and yfa carbs are my nemesis--gonna build the holley 1940--looks like the roch 2gc problem has been the power valve and i found a good place to buy individual carb parts instead of buying a whole kit--i bookmarked so many--i'll compile them later

please add your fuel knowledge

No doubt fuel has been reformulated but not sure on the evaporation rate. When it's dried out there is a lot more gooey shit left than the old days so I'm thinking there is also more heavys in with the lights. YFs are great until you have to fiddle weith them and then they never work right again. The powervalve/accelerator pump design is pure evil. Ifn it was me, I'd try a rochester 1 barrel from a 250 or a 292. If I get time to mess with my 300, the 390 Holley is out and probably a 2100 in it's place.

i found a kit locally for 20 bucks at autozone for the older of the 2gc's i have, so gotta get started on that

holley 1920's are now wall hangers--no floats available--how 2 make a float????

1 more try and the van becomes permanent storage or hideout room

mostly i was thinking about the throttle shaft clearances being affected by the thinner fuels--i have found some confirmations of the much faster evap rate on current gasolines

i would say go with the 2gc on your 6 JB--seems like the parts availability is better and they are easy to find on ebay--the direction is right for throttle linkage adaptation, too--i let one pass that was a fresh pull--went for 51.00

If its got the brass float, I think ya can fix those if your really good with resoldering.

just would have to make sure ya didnt add weight to the float. Maybe use a gram weight scale to take a before and after weight.

Im sure you could ask a local kid if their dealer were willing to let you borrow one for a little while. LOL

Just use the scale at the Post office. Less chance of getting shot