1925 Model T Coupe

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Model T Ford Forum: Forum 2012: 1925 Model T Coupe
Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Bowman on Friday, July 06, 2012 - 02:28 am:

Guys, I have a 1925 model T coupe that quits firing on the rear cylinder if I coast too long. It seems to want to foul the plug as if it is running too rich. Which way do I turn the carb. adjusting rod, that is mounted inside the cab on the right side, in order to lean out the mixture.
The engine seems to smooth out when the adjustment is about 3/4 turn counterclockwise from full closed.
I think what is confusing me is: does the adjustment control the amount of air that picks up the fuel and permits the mixing of the fuel mix.....or does it control the amount of raw gasoline that is fed into the mix. It would help me to know ( without me pulling the carb off for analitical inspection, just what is happening with the turning of the control rod.
Thanks for any input. Tee


Top of pagePrevious messageNext messageBottom of page Link to this message  By Craig Anderson, central Wisconsin on Friday, July 06, 2012 - 02:43 am:

It's a fuel adjustment.......so open is.......open...... LOL
Your current setting seems about average.
Zoom zoom zoom wide open and turn the knob clockwise until the engine falters.
Open it till it smooths out......then just a little more.
Too lean will make it run hot and too much wastes fuel and causes popping when you let off the throttle when slowing down.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Friday, July 06, 2012 - 09:22 am:

I open my Holley NH about 1 1/2 turns counter-clockwise from fully closed for the initial setting and once it starts, do not have to adjust much from there. At just 3/4 of a turn, it sounds like you may have yours so lean that, not enough fuel is getting to the farthest cylinder. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Sosnoski on Friday, July 06, 2012 - 11:26 am:

Jack,

The throttle plate on the carb. adjusts how much air is being drawn into the carb. This is controlled buy the throttle lever on the steering column. The mixture adjustment regulates how much gas is being drawn into the air flow, thus regulating the air/fuel ratio. If you have to much fuel or to little fuel it will not run right. You want to run it towards the rich setting as running to lean may cause overheating problems.

Start the engine and run it at a fast idle. Turn the mixture adjustment clockwise until it starts to run rough (lean fuel mixture). Now turn it counter-clockwise until it starts to run rough again (rich mixture). Now turn it clockwise again until it smooths out. This is where you want to run it.

This setting may change depending on the temperature of the engine. A cold engine will require a richer mixture than a hot one. When you are first starting it you may need to richen the mixture 1/4 turn counter-clockwise. As it warms up you then need to lean it out (clockwise).

Hoe this helps.
Dave S.


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