Weber 32/36DGV verses the Weber 38DGES

yodta
(pooh bah)
Sat Mar 12 2005
01:35 PM
Sarge
(carpal tunnel)
Sun Mar 13 2005
01:40 AM
response goes away . When these things are dead-on, it's like efi...
Sarge
Re: Weber 32/36DGV verses the Weber 38DGES
by lean air jet you mean larger in size, correct?
my sec. still felt lean at
75/70
135/145
175/180
so I went to
75/70
140/150
175/180
the prim. feels kinda heavy at 2800 unless I put my foot in it and take it up to the limit of the primary.
the secondary feels a little sloppy, too. do you think going to 180/185 on the airs, possibly backing the prim. main back to 135?
on the ramflo -- are you supposed to oil the foam?
also, at which point do you really need increased airflow that a standard filter cannot provide?
is it really that much more beneficial to have the air flowing directly downward as opposed to in and around a 90* like with
conventional stack filters?
about the "let up a bit & it's better" -- I read that that's due to a lean condition, not rich. the opposite of what you're saying.
Re: Weber 32/36DGV verses the Weber 38DGES
The "let up and it's better" can apply either way, just depends upon throttle position, rpm and velocity. I was referring to wot in the
primary, hence recommending it be leaner on it's air jet (larger #).
"The primary feels heavy at 2800 unless I put my foot in it"
That statement says a lot , at that rpm the velocity is not that high and the air jet is not affecting the circuit all that much. Dropping
the main would help that response a bit , but in turn the air jet may have to come down a bit with it since you describe "take it to
the limit of the primary" as helping it out . That also says the air jet in the primary is very close to correct with the current ratio. So,
I would take the primary to this step since you are very close:
Idle:75
Main:135
Air: 170
If this change exhibits a sluggish or flat spot at 1/3 throttle then the main cannot be dropped any farther. The trick here is to make
a happy enough medium between the idle/transition stage and main cruise. Since your idle is already at 75, I doubt it will accept
the change but it's worth a try. Also note that at this point float settings wil greatly alter the way the main circuit works when jetting
is this close. Too low a float and you push the main circuit's timing up higher since it doesn't have the fuel available to mix into the
emulsion tubes. You could run it a tad on the lean side and use an F6 tube to bring the curve down lower and richer, but then the
upper end has be adjusted to match it . Some F6 combo's run best with a 155 air jet since the upper range is not mixed with air
the same way. Amazing how little difference in those drilled holes make , you wouldn't believe it . Same diff with engines that pull
too hard/rich in the mains, switching out to F15's will take care of the problem.
The secondary "feels a little sloppy", I assume this means a lack of response unless you hit wot in that throat. Again, since the
velocity at the point of cracking the secondary open is so high you may just try backing the secondary idle jet down just a bit . Try
to stay one notch above the "flat spotting" that shows up with too small a jet. One notch past that point keeps the mix more
managable to make the transition. Remember, as that second barrel is opened the overall velocity drops more unitl the point of
the engine at full song. Most motors will not make full velocity speeds in the carb's throat unless they breathe an exponential
amount of air . Most cams are not timed this way, they bridge the gap between gaining power and air velocity with rpm's and low
end torque. Most of the Jap cams actuall do breathe better with rpm's right almost up to redline, these are the types that benefit
the most from flat jetting curves. The one you have does not, so you must jet according to velocity values instead. Therefore,
secondary jetting really needs to lean out a lot at wot in the second throat . Bigger air jets and basically small mains should work .
Try this , and carefully note throttle position and it's effect at different rpm's...
Idle:65
Main:150
Air:185
I hope you are keeping notes on jetting changes, it can get confusing and is easy to get lost . Careful notes about changes with
notes added to driving response helps a lot , it's almost like homework all over again. Too bad we all can't afford a dyno and
sniffer, it would make this so easy.
Ramflo
The filters really do not need to be oiled like the K&N's. The whole idea of these filters is to allow the carb to breathe straight into
the throats as the carb was designed to work. If you want any clue as to any difference, run without a filter once in a clean area
free of dust. Most Webers run awesome without a filter, in fact a lot of the SCCA guys used to do just that as well as remove the
choke blades. Some even went as far as to cut the choke housing's casting off and taper the top of the carb , much like modern
day Dominators. The K&N's design of having to go "up and over" that choke housing kills the carb's efficiency pretty fast. The
biggest effect is wot , but some driveability issues also show up as well as overall economy. Some guys have done comparison
tests with the K&N and Ramflo side-by-side on twin sidedraft carbs. The Ramflo's two cylinders ran much cleaner on the plugs
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