1926 Carburetor Mixture Adjustment

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Model T Ford Forum: Forum 2017: 1926 Carburetor Mixture Adjustment
Top of pagePrevious messageNext messageBottom of page Link to this message  By Randy Roberson on Wednesday, May 31, 2017 - 03:34 pm:

Hi, I am new to the Model T world so I have a question: does the mixture adjustment have limits at each direction of rotation, or will it just continue to turn in one direction?
My car seems to require more and more fiddling with the mixture adjustment to keep it running. I plan to dismantle and clean the carb up, thinking that it may have dirt or varnish from a lot of sitting around.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Wednesday, May 31, 2017 - 03:43 pm:

Turning clockwise leans the mixture. It will usually misfire and/or stop running before the mixture knob is all the way in, but be careful not to force the needle. You can damage the needle if you turn it down too tight. In fact, that could be why you have to keep "fiddling". The needle is cone shaped and when it becomes worn, it gets a groove in it and will then be hard to get the best adjustment.

Turning counter clockwise richens the mixture. It will usually begin to lope and run rough maybe even blow some black smoke as you enrichen the mixture. The best place to run the engine is half way between too lean and too rich where it runs the smoothest.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brad Marble on Wednesday, May 31, 2017 - 03:47 pm:

Randy; If you turn it counterclockwise it will come right out of the carburetor,however the linkage used on the 1926 T will only let you turn it about 1/2 a turn in ether direction. Normally 1 and 1/2 turns open when cold and a 1/4 turn less when warm works well. Brad.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry Davis Houston TX on Wednesday, May 31, 2017 - 03:57 pm:

From an entirely closed position, I back off, counter clockwise 1-1/2 turns and that becomes my starting position. Usually only a quarter turn in either direction set's the engine running smoothly. Once it's set, it's set. Maybe a tweak every now and then but..... Let it warm up before becoming too twisty.... My thoughts only for what it's worth.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, May 31, 2017 - 04:09 pm:

Yes, the needle one to 1 turns out is a good place to start. When you set it between too rich and too lean, I would do it while cruising down the road. That's where you want it to run best.

If you find the needle is grooved as Norm described, here's how to fix it:

https://www.youtube.com/watch?v=uTiStUTU9IE


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Smith, Lomita, California on Thursday, June 01, 2017 - 11:00 am:

I realize the mixture must be adjusted to the area where you live, but once I set mine, I leave it alone. I don't fiddle with it all the time.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, June 01, 2017 - 12:07 pm:

Me too. I suppose if I was running farm machinery powered by the car, or driving at a considerably higher elevation, I'd want to reset it for those running conditions. But in normal driving, once it's set I don't see any need to mess with it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Friday, June 02, 2017 - 06:57 am:

The only time I had to open up a quarter turn when using a NH was when it was freezing cold outside, but you really don't want to drive an open T when it's so cold..

You may also have problem with fuel flow - open the drain under the float bowl with a bucket under and check if you have free flow that lasts. Problems can be caused by rust in the tank, low on fuel or a cap without a venting hole.


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