As you stated Daniel, yes it looks like you have two jets (little triangle
hanging over the edges of both throats) with the DGV having the
secondary opening closed off.
The caveat here is this is not the jet. This is only the orifice that aims
the gas at the carb throats. The pump jet is the 'bolt' that holds this little
triangle in place....and yes... it's rather easy to ream it out to size.
Quite a few carb manufacturers (as well as other tool makers)
make drills and pin gauges for adjusting (drilling/reaming out) jets
to precise sizes. Normally you' simply buy two jets. Drill one out step by step
testing each size. When you realize you've gone past the right size
you simply ream/drill the second to the last size that worked right
before the performance drop.
Although not specifically for the LBC world, two articles
http://dimequarterly.tierranet.com/articles/tech_carb_tuning_guide.html
and
http://dimequarterly.tierranet.com/articles/tech_weber_tuning.html
give very good directions and information concerning tuning downdraft Weber
carbs
for engines very near our sizes
A more generalized but also reputable source
http://www.racetep.com/weberadj.html
And one more reference showing a variety of DG pump and bleed jets in use
http://www.efn.org/~msayer/weboem.html
Paul Tegler wizardz@toad.net http://www.teglerizer.com
----- Original Message -----
From <Daniel1312 at aol.com>
To: <ptegler@cablespeed.com>; <MartyWit@aol.com>; <spridgets@autox.team.net>
Sent: Tuesday, October 31, 2000 2:35 PM
Subject: Re: Weber DGV jet selection
Paul,
Well Ok I am strictly speaking wrong. However, my Haynes book on Weber ISBN
1 850 10 061 6 is obviously different from yours. Also my Weber book
published by Weber lists only one part number for the accelerator pump jet
and this is: 76226
More than one variant of DGV carb was made and I have known people modify the
pump jet from one carb to fit another - by using a jet from the DFAV, & DGAS.
But because these carbs are synchronised opening rather than staged like the
DGV you need to find a way of blanking off one of the jet holes (if you look
at the DGV you see that while it appears to have 2 jet holes one is in fact
solid). If you use the 2 hole jet one jet sprays fuel against a closed
(secondary) butterfly.
It is also possible to drill any given Weber jet (I think Weber made the
drill bits) to increase the size of the hole.
In any event I doubt very much if a stumble from idle is going to be cured by
an increase in acceleration jet unless Marty is mashing the throttle to the
floor from idle. The DGV will be fuelling from the progression holes at idle
until the primary butterfly opens the idle jet fuels, revs climb and
STUMBLES. Only with further throttle opening the main jet circuit (still all
on the primary butterfly opening) fuels with assistance from the pump jet
circuit. If the carb is running right everywhere aside from idle I don't
think the problem is going to lay with the accelerator pump.
Of course I can't be sure about this because Marty hasn't answered the
questions I posed earlier.
1312
In a message dated 31/10/00 17:38:52 GMT Standard Time,
ptegler@cablespeed.com writes:
<< WHat? Yes it is! So is the pump discharge blanking needle!
Accel pump jets are avail in sizes from
.30 to .65 ( I have .30 .35 .40 .50's in front of me in hand)
accel pump back bleed (called a pump discharge blanking needle
in a DGV) .40 .45 .50 .65 .70
and I'm sure other exist, I just don't (haven't used) have them in front of
me.
check Haynes Texhbook Weber Carb Manual ISBN# 1 56392 157 x
page A1-2 (part 5 Appendix 1) lists some of the variations used for
different
vehicles as OEM equipment. (amoung other listings avail. throughout the
book.)
Paul Tegler wizardz@toad.net www.teglerizer.com
>>
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