OT - probably a stupid question about setting a carb float?

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Model T Ford Forum: Forum 2016: OT - probably a stupid question about setting a carb float?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Eastern Nebraska on Saturday, May 28, 2016 - 10:21 pm:

We have a Buffalo carb that when "dialed in" at speed or for aggressive acceleration, is too lean at idle. The carb has very little in the way of adjustments, just two "gasoline nozzles" that protrude up in the intake chamber, and a cone that when rotated, allows more air to be drawn through the intake. Where the float is set determines how high (close to the top) of these tubes the gas "sits." When the cone is rotated, the increasing draft draws and mixes the gas from the two nozzles.

I wonder if a lower float setting would mean less gas is drawn into the "gasoline nozzles" at idle? Maybe at speed the height of the gas is less critical to mixture because of increased vacuum?

This ad shows the outline of the intake chamber and nozzles. The ad also lists makers using the carburetor.

Maybe some other modification or adjustment would help?

Thanks for your suggestions or opinions,

Rob


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Rogahn - Davisburg, MI on Sunday, May 29, 2016 - 05:45 pm:

Rob,

I'll take a whack at it... since this carb has one circuit, it looks to me that one must balance the tune between idle and wide open throttle. This means you will have to adjust the cone and fuel adjustment needle to get the best if both but that also means it will not be at the "sweet spot" during WOT.

In pursuit of obtaining fuel enrichment at idle I wonder if you have an air leak of some sort that is more prominent with the throttle closed? If you know there are no leaks anywhere between the throttle blade and intake valves, then I would look at adding and idle circuit to the carb like newer up/side draft carbs have, like a Kingston or holly G.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Rogahn - Davisburg, MI on Sunday, May 29, 2016 - 05:50 pm:

Btw, it was good to see you and the K at the OCF last year. We met at the tavern, but didn't have much time to talk. I'm making sure to spend some time up close to your K to study it. I think they are fabulous cars.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Rogahn - Davisburg, MI on Sunday, May 29, 2016 - 06:55 pm:

Sorry for not answering your question during the first post. Is your theory that the higher fuel level gives slightly higher head pressure at the tip of the needle, thus requiring less pressure difference across the cone to draw fuel through the tubes? It's possible, but low fuel level doesn't usually affect idle as much as WOT.

I think that by closing off the air flow on the cone a little should increase the dP across the cone at idle and draw more fuel without the need for adjusting the fuel needle


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Eastern Nebraska on Monday, May 30, 2016 - 06:13 pm:

Aaron,
Thank you for the reply. My theory is, if the float level is lower, the level of gas in the tubes, noted in the diagram as "gas nozzles," will be lower, and thus leaner on idle (and vice versa with higher float setting).

Then, with higher rpm, would the float level be less important, as the increased suction from the revving engine draws more and more gas from the tubes, with less importance to how high or low the gas is in the tubes (nozzles).

I guess what I'm wondering is, otherwise, what difference would float level make on this carb, other than to keep the gas from running over if the float were set too high?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Rogahn - Davisburg, MI on Tuesday, May 31, 2016 - 08:38 pm:

Rob,

As an engineer, I am at a point where I'd opt to test the theory to see if a higher float level would help or not. I am a junkie for data and it always proves worth while. I hope you try it and let me know the results...

Regards


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Rogahn - Davisburg, MI on Tuesday, May 31, 2016 - 08:43 pm:

I'd love to study the guts of that buffalo carb and throw it on a flow bench as well, but I'm guessing they aren't that abundant.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rob Heyen - Eastern Nebraska on Tuesday, May 31, 2016 - 09:05 pm:

Aaron,

Actually.........

Between three K owners, we have three Buffalo carburetors, and two aren't presently on cars.

Where shall we send one?

:-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Rogahn - Davisburg, MI on Thursday, June 02, 2016 - 12:08 am:

Pm sent


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