[c.helleri]

Do any of you out there have any good info regarding which emulsion tubes to use in Weber IDA carbs? I'm having a difficult time getting the F11s to work in my 2276.

 

[Volks63]

F7

 

[c.helleri]

Thanks for the reply Volks63. Have you experimented with any other emulsion tubes? I also have F2s and F4s to fiddle with. Just wondering if there is any rhyme or reason you suggested the F7s.

 

[dragvw2180]

When I ran IDA's I used F2 tubes but only used for racing . It seemed to richen up at higher RPM's . Mike McCarthy

 

[c.helleri]

Thanks Mike. I have those on hand and believe I've tried them, I'll have to look back at my extensive list of jetting adjustments. My idle circuit seems to be happy with a 100 idle air and 65 idle fuel jets. I'm running into trouble with the transition from idle to main circuit. My wideband shows and I can feel the engine go way rich with a main stack of 180 air correction, F11 emulsion tube and 145 main jet. This is too the point of fouling the plugs until I get higher in the RPM range say about 4500RPM then it'll lean out to a desirable 12.5:1 AFR. I need to find an emulsion tube that isn't so aggressive in the progression...tips in a bit slower.

 

[Volks63]

emulsion tubes

Try 160 main, 180 air f-7 emulsions f10-60 idle 42 vents.

 

[c.helleri]

The crazy part of the equation.... when on Dave Kawell's dyno the engine lost power with the 40mm venturis, gained MUCH power with the 37mm vents... The heads are 42X37.5 DRD L6s. My CR is set at 9.6:1, so should be right for the Web 86B cam.

 

[Volks63]

jetting

With the F-11 try dropping the idle to 60 see what that does and if not try dropping the mains to 140. I was running a similar combo with f-7 and had a bad hesitation off idle and went to the f-11 and it took it out. If this doesn't work I would try the f-4 and would keep the 37 vents considering the lower compression and smaller camshaft. If you have to large idle jet it can mask the transition or can also cause an over rich when the mains come in. good luck.

 

[c.helleri]

Volks63, I have tried the 60 idle fuel jet with the 100 idle air. It runs lean at the top of the idle circuit. The wide band shows 14.7ish:1 with the 60f10 idle fuel. with the 65 idle fuel it's just about right. I have 135 mains then jump to 145s... I may order a set of 140s just to give it a try. I do have and can try the F4s. I agree that a big giant idle fuel jets can play havoc in the transition and when the mains come on. I can see it on the wideband. Thanks...It's all about timing the events and knowing which way to make it turn on/off.

 

[c.helleri]

So, I decided to start from scratch. I removed both carbs and reset the float height( the shop that I sent the carbs to for rebuild somehow overlooked this major detail but the carbs "ran GREAT!" on their test engine.) The floats were so far off, it was despicable. I also reset the needle and seat height to the specs in my Weber manual. With the idle jet stack the same (100/65) I started with 200 air correction/F2 emulsion/145 main. The AFRs were rich at the top end of the RPM band. I swapped the 200 air jet for a 210 and it didn't clean up much. I read that the F2s do tend to run rich at the top end. Now I'm waiting on a set of 140 mains. Otherwise I'm pleased with the outcome of the maintenance I did to the carbs.

 

[Fiatdude]