dfev screw question

[timspider]

ok, working on learning to tune a weber dfev 32/36. It's about 6 months old with maybe 3000 miles on it.
Going through weber literature and a detail page at redline.
http://www.redlineweber.com/html/Tech/c ... _best_.htm

have identified 3 screws so far:
idle stop screw
idle speed screw
mixture screw
I took out the mixture screw and sprayed it with carb cleaner- it was mostly black but the stuff rinsed right off.
my question is about 2 other gold screws, situated high in the body, neither of which have a spring and both just seem to screw all the way in until fully seated. One of these was pretty dirty when I pulled it. the other one towards the engine block, was not.
In the picture, it is the gold screw near the top- this one is facing the drives wheel well. there is another one on the opposite side- questions: what are they? should they have springs and be adjusted or are they ok springless and screwed all the way in tight?
If I have this right, the one on the bottom of this picture is the mixture screw whose baseline is 1.5 to 2 turns out.
thanks much

[kilrwail]

The screw at the bottom of your picture, with the spring, is the idle mixture adjustment. Any screws without springs or lock nuts are either attaching pieces together or are just plugs, like the one in your picture.

[carl]

The screw you refer to, just above and to the right of the accel pump housing in your picture, it the jet holder for the idle jet. As noted, there is one on each side, as each venturi has it's own idle jet. There is nothing to adjust, the screw just holds the jet in place.

[kilrwail]

The screw you refer to, just above and to the right of the accel pump housing in your picture, it the jet holder for the idle jet. As noted, there is one on each side, as each venturi has it's own idle jet. There is nothing to adjust, the screw just holds the jet in place.

Quite right - my mistake.

[phaetn]

Yes -- the gold screw at the top is just the holder for the primary circuit idle jet. On the other side it's for the secondary circuit. Weber specs for the primary idle is .60 and .50 for the secondary, though lots of people here mention using slightly smaller for primary (.57 or .55 even). YMMV.

To access the mains, air correctors, and emulsion tubes you have to take off the air filter and top of the carb.

Cheers,
phaetn

[timspider]

thank you Canadian friends. that helps me to understand what is what. I think I got it cleaned up pretty well. Now to get the tuning part right. she seems a little fuel starved or stuttery when under load. I have a lot of hills around here so she has to run well under a little load. Just grateful to have her back to drive for the last few days.

[phaetn]

thank you Canadian friends. that helps me to understand what is what. I think I got it cleaned up pretty well. Now to get the tuning part right. she seems a little fuel starved or stuttery when under load. I have a lot of hills around here so she has to run well under a little load. Just grateful to have her back to drive for the last few days.

Lots of people have had a similar issue with the same carb. Might be the carb, might be something else (valve clearance, timing). I've just sort of learned to live with it and work around it. I sometimes just get a hesitation at a certain point with a balanced throttle, but flooring the throttle gets rid of it, so that's what I do. I haven't even been able to figure out if it's a lean or rich condition, as the plugs look good, and switching idle jets across a wide range hasn't seemed to help. Might be carb float height, too.

Perform a search on the forum and you'll see quite a bit of discussion about it. I think one fellow found a fix by shortening the variable linkage for when the mechanical secondary comes in (i.e. he made it come in earlier). I have yet to try it.