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lean at 4k under light load


ray_

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I customized my emulsion tubes by soldering up some of the holes.  I will try to find the post.   On some random Alpha website, you can order customer emulsion tubes. 

 

If memory serves, take out the emulsion tube,  turn it upside down.  From the top down represents the rev range where you want to fatten or lean it up. 

 

Mine was lean at 4K and above.  I covered the two top holes (opposite of each other), and it helped pull it into the 14's.

 

Sorry Ray if you already were aware of this. 

 

Regards

 

 

 

 

 

 

 

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"Goosed" 1975 BMW 2002

 

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52 minutes ago, Dudeland said:

I customized my emulsion tubes by soldering up some of the holes.  I will try to find the post.   On some random Alpha website, you can order customer emulsion tubes. 

 

If memory serves, take out the emulsion tube,  turn it upside down.  From the top down represents the rev range where you want to fatten or lean it up. 

 

Mine was lean at 4K and above.  I covered the two top holes (opposite of each other), and it helped pull it into the 14's.

 

Sorry Ray if you already were aware of this. 

 

Regards

 

 

 

 

 

 

 

 

Thanks, that's very cool.  And Zinz's youtube link. I  didn't know that but I suspected e-tubes and  expect that's where I'll find a/the solution.

 

Cheers,

 

Ray

Stop reading this! Don't you have anything better to do?? :P
Two running things. Two broken things.

 

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There is no real guide to Weber emulsion tubes. That I can find none of them really step from one to the next. I think I'm running F56's in mine and it's OK. I'd like a little richer at cruise though....

-Nathan
'76 2002 in Malaga (110k Original, 2nd Owner, sat for 20 years and now a toy)
'86 Chevy K20 (6.2 Turbo Diesel build) & '46 Chevy 2 Ton Dump Truck
'74 Suzuki TS185, '68 BSA A65 Lightning (garage find), '74 BMW R90S US Spec #2

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What kind of carb? If it is leaning out at that rpm under light load it could also be the idle jet running out of gas before the mains take over and you have a lean gap between the 2 circuits.  So either get your mains in sooner (larger main or smaller air corrector or smaller choke-depends on severity of change required) or a larger idle jet. What AFR does it idle at and WOT at?

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Idle is 12-ish. Cruise is generally 14.5-ish. I am going rich under moderate load, maybe 12 or less at times so that could stand some fiddling. WOT is 12-13 and also maybe richer at times.  The lean window is pretty narrow; JimK may be right, with  no AFR gauge I may not have made this post! 

 

Your proposed correct above would get me richer in other areas I would think. And that's not really where I need to head. I do believe you are correct about the issue occurring at transition.

 

Oh, cam is a Shrick 284.

 

Thanks,

Edited by ray_

Ray

Stop reading this! Don't you have anything better to do?? :P
Two running things. Two broken things.

 

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Has anyone ever changed where the transition happens by 'adjusting' the linkage?

 

Could it be advantageous to bring the secondary side in sooner?

 

(not sync-linking)

 

 

     DISCLAIMER -- I now disagree with much of the timing advice I have given in the past.  I misinterpreted the distributor curves in the Blue Book as timing maps for our engines.  I've also switched from using ported-vacuum to manifold, with better results.  I apologize for spreading misinformation. 

(3-28-2024)  

 

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Wouldn't it be strange for the idle jet to main jet transition at Ray's 4000-4200 rpm to be causing the lean spot?  A poor idle jet match is really apparent coming off idle and if fixed at off idle condition, should be ok at a much higher rpm.  It's the air velocity thru the venturi that makes the changeover happen.

A radiator shop is a good place to take a leak.

 

I have no idea what I'm doing but I know I'm really good at it.

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Yeah. We're talking 70mph so that's like 40% throttle on that car. And a previous small idle jet produced that transition stumble where you'd expect.

 

Which way would you go with the venturi?

 

Cheers,

Ray

Stop reading this! Don't you have anything better to do?? :P
Two running things. Two broken things.

 

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