I am probably going to get myself in trouble here. I dont usually post
to
subjects that I am not fairly sure I know something about. So right up
front let me say that I do not have a good handle on this whole subject
of exhaust size and jet size.
You're correct and your indications pretty well back it up. We all face
the dilemma of replacing worn out exhaust components as these things get
older, but actually, it's a two-fold problem. Reduced back pressure
does indeed require going to slightly richer jetting, I don't think
there's any arguments on this and the carb guys support this across the
board. Secondly, the oxygenated crap that called gas these days causes
carbureted engines to run lean. The Carb guys pretty much want you to
step up 2 jet sizes to accomodate this crap.
I was just about to pull the carb on my GMC when the news about
switching to yet another alternate fuel hit the headlines. Fuels with
MTBE additives are almost history now that 20% of the nations drinking
water is contaminated....oops, another story. Anyway, now it would be
smarter to wait and see what happens with whatever replaces the crap in
the pumps before rejetting. I'd hate to wind up with something that
won't pass emissions testing.
Off the soapbox,
Steve
to
subjects that I am not fairly sure I know something about. So right up
front let me say that I do not have a good handle on this whole subject
of exhaust size and jet size.
You're correct and your indications pretty well back it up. We all face
the dilemma of replacing worn out exhaust components as these things get
older, but actually, it's a two-fold problem. Reduced back pressure
does indeed require going to slightly richer jetting, I don't think
there's any arguments on this and the carb guys support this across the
board. Secondly, the oxygenated crap that called gas these days causes
carbureted engines to run lean. The Carb guys pretty much want you to
step up 2 jet sizes to accomodate this crap.
I was just about to pull the carb on my GMC when the news about
switching to yet another alternate fuel hit the headlines. Fuels with
MTBE additives are almost history now that 20% of the nations drinking
water is contaminated....oops, another story. Anyway, now it would be
smarter to wait and see what happens with whatever replaces the crap in
the pumps before rejetting. I'd hate to wind up with something that
won't pass emissions testing.
Off the soapbox,
Steve
