weber mods anyone?

[jwetering]

Has anyone here ever done the weber float bowl modification that Bruce Anderson describes in his Performance Handbook? Specifically, he says to grind away the standoff around the fuel pick up in the bottom of the float bowl, making it so that fuel can be picked up off of the bottom of the bowl. Then he says to build a small dam (parallel to the bottom of the bowl) to keep the fuel from sloshing away from the fuel pick up.

I'm interested in doing this because I am experiencing what appears to be fuel pick up problem when autocrossing. I checked the float levels using a gauge I got from PMO and they're way up there at the top of the two lines...ie definitely not low, maybe too high?

Anyway...if anyone has done the mod according to BA's book I'd love to hear from you.

Thanks
Jasper

[jluetjen]

I just did a set of carbs that I have, but I haven't put them back together with the additional baffle yet. Even when I do I'm not planning on using them until some time in 2005 (unfortunately).

I didn't find any issues. I just used my handy mototool to do it.

[126coupe]

I did the standoff removel on my webers on my Racecar. It cured a slight gurgle I had at willow springs coming down the hill. I did not do the dam thing ( would like too purchase the dams though)Where?? The downside is you have a greater chance of dirt getting to the jets. This mod I recommend for race cars where the carbs are being taken apart all the time and cleaned. Street cars I would stick w the dam

[RoninLB]

maybe, if the carb fuel lines are set up as a dead end at each carb, it's a fuel supply weakness. Tyson has been setting the fuel supply lines in a full loop. From one carb to the next carb, to the return line with success.......Ron

[jwetering]

Thanks for the feedback guys. Here are my thoughts....

1) I'm making my own dams from .010" brass "shim stock". I'm just cutting them to fit using a pair of tin snips using the picture in BA's book as a guide.

2) I guess the question I have is about orientation. If the dams are exactly parallel with the bottom of the float bowl, then I don't see how they would be that effective in keeping a whole lot of fuel near the pickups. I could see if the dam is perpenducular to the wall of the float bowl, but the picture doesn't show it oriented that way. Has anyone seen these dams in real life?

3) If the dam is laying on the main jet channels, then you pretty much have to grind away the standoffs, otherwise the dam would block the fuel pick ups entirely. My gut feel is to leave the dams out and just grind open the fuel pick ups (I am planning to use a dremel). I'm not sure what kind of epoxy I would use to secure the dams in place. Any suggestions? I'm not *too* worried about dirt in the float bowls. They should be easy to flush out if you remove the main jets and just spray some cleaner into the floats. I'd do this at every oil change or something. By the way...Richard Parr at PMO said tha Gerry Woods will do the mod for you for $$. I'm guessing he'd sell you a set of dams too. Maybe I shoudl call him now that I think of it.

4) The idea to run a loop is interesting, I don't believe my fuel returns to the tank at all right now. The lines just dead end at each carb. hhmmm.

Thanks again guys.....I just need some basic tips on designing the dams from someone who has seen them.

[jluetjen]

From one carb to the next carb, to the return line with success

What return line? If there was a return line you'd need some sort of pressure regulator like the FI cars have to keep the fuel pressure up between the pump and the carbs. From what little I've heard of this idea it's left me more confused rather then enlightened. Does someone have a schematic of the layout described?

2) I guess the question I have is about orientation. If the dams are exactly parallel with the bottom of the float bowl, then I don't see how they would be that effective in keeping a whole lot of fuel near the pickups. I could see if the dam is perpenducular to the wall of the float bowl, but the picture doesn't show it oriented that way. Has anyone seen these dams in real life?

I've made a set myself and I'm going to just epoxy them parallel with the bottom of the float bowl lying on the channels. I believe that they should be butted up against the outside wall of the bowl. When the fuel sloshes towards the main jets, the dams will trap the fuel against the jets rather then let it ride up bowl wall. In a one G turn I'd expect the surface of the fuel to make a 45 degree angle to the bottom of the bowl. When the fuel sloshes away from the jet by turning in the opposite direction, rather then letting the jet becoming exposed, the fuel trapped by the dam will be like water trapped in an upside down glass that you lift out of a sink full of water. The dam will keep the some fuel trapped up next to the jet by suction. As a result the carb won't run lean.

[RoninLB]

Originally posted by jluetjen
What return line? If there was a return line you'd need some sort of pressure regulator like the FI cars have to keep the fuel pressure up between the pump and the carbs. From what little I've heard of this idea it's left me more confused rather then enlightened. Does someone have a schematic of the layout described?

to quote Tyson
"If you replace the the 2 forward banjo fittings on each carb with ones that have two outlets just like the rear banjo fittings, then you can run a hose from the left carb to the right carb so that the fuel will flow through the left carb's banjo fittings, then over the the right carb's, then back to the tank.

This way there is no restriction, so the high pressure CIS fuel pump can't build high pressure. Rather, you end up with low pressure and very high volume, as well as very cool fuel since it is constantly being recirculated back to the tank."

Tyson puts the regulator before the return line

[jluetjen]

Interesting...

Tyson puts the regulator before the return line

Just the stock CIS regulator? I'd be concerned that there would be too much pressure and flood the carbs.

I'm interested.

[RoninLB]

Originally posted by jluetjen


Just the stock CIS regulator?

a low pressure carb fuel regulator.

I'm doing the install now.. I should have more hard info soon

[Chuck Moreland]

I'm doing a similar setup using a 4 psi check valve as a regulator. I won't be using the CSI pump though. I'll report the results.