jg1000

So I just purchased an 84 GSL from a member on here who purchased it from another member on here. It has a half bridge ported 4port 13b with down draft weber 48mm ida carbies. it has racing beat header and muffler 2.5" exhaust . So I haven't had a chance to put a wide band on it but has a real lean spot on transition off of the idle circuit. I thought that maybe the float adjustment might be the cause but I pulled the jets out and I have a

135 air corrector jet
F8 emulsion tube
185 main jet
10/55 idle jet

According to racing beat http://www.racingbeat.com/manuals/16602%20Weber.pdf

they have the main jet around 230. Their site doesn't have my exact setup but 185-230 is a large difference. However after the transition lean stumble the car runs smooth to redline.

j9fd3s

iTrader: (3)

typically there is a lean spot between the idle and main circuits, however with an F8 tube its possible to have a RICH spot there.

some things you can try:

the air corrector controls when the mains come on, you might try a smaller one (comes on sooner) or a larger one (comes on later, start with richer first). it is perfectly valid to put a tooth pick in there, or remove it completely

second thing to try is a different idle jet.

for what its worth, i have a 12A P port, and my jetting is close to yours, i started with the RB jetting, and it doesn't run at all, i suspect that their open exhaust and my muffled exhaust make a huge difference...

jg1000

Great advise!

So you are saying I can just block off the air corrector jet and it will cause the main to come on much sooner ?

The idle jet Seems about right with 2 turns out on the adjustment.

j9fd3s

iTrader: (3)

2 turns out is ok, but the "ideal" is more like 1 turn

Re the air corrector if you look at a cross section of the main circuit it looks like a lower case "t" with only one side of the cross. at the bottom is the fuel jet, and at the side is the passage into the venturi, and then engine. at the top is the air corrector.

so the air passing through the Venturi puts a vacuum on the fuel passage and pulls the fuel up and over, and into the engine. the air corrector sits at the top, and mixes a little air in with the fuel, but it also acts as a vacuum leak on the engines signal.

so if you make the air corrector really big, the main will have a bigger leak, and come on later, really small has the opposite effect. its perfectly valid to just plug the air corrector (tooth pick), to see what it does.

jg1000

Ok so I got a wideband hooked up and I was correct. Right around 2000-2500 it goes way lean. If I plug the air corrector jet it seems to help some but runs way rich up top. Right now I am with a 55 idle jet. Should I go down to a 45? or even a 40?

j9fd3s

iTrader: (3)

with the idle jet, smaller number = smaller hole = less fuel, so if anything you'd want a 60.

if it goes lean @2000-2500rpm, than you either need to get the main circuit working sooner, or the idle/transition circuit to keep working longer. or a little of both.

the idle jet holder has an air hole, and off the top i think the default is a 120, getting a 100, or making yours a 100, will extend the idle circuit a little higher.

you can also drill a 3rd transition hole, if your carb doesn't have it already.

jg1000

3rd transition circuit? Do you have a link for this ? When I plugged the air corrector it still stumbled hard at the same rpm so I think my correction needs to be else where .