Carb question
09-09-2003 | 09:21 PM
#1
Thread Starter
Senior Member
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Carb question
I've noticed that the low end needle adjustment screw lengthens or shortens the 'sleeve' when you look down inside the carb venturi.
I've also noticed that some engines (TT Pro .46) are tuned nicely when the sleeve does not cover the spraybar, while my GMS .47 looks like the spraybar continues all the way across the venturi opening..
Are these 2 different types of carbs?
How does that sleeve work when the spraybar is completely covered by it?
Is there a good website with the mechanics of this explained?
Thanks.
Dave
I've also noticed that some engines (TT Pro .46) are tuned nicely when the sleeve does not cover the spraybar, while my GMS .47 looks like the spraybar continues all the way across the venturi opening..
Are these 2 different types of carbs?
How does that sleeve work when the spraybar is completely covered by it?
Is there a good website with the mechanics of this explained?
Thanks.
Dave
09-10-2003 | 12:45 AM
#2
My Feedback: (16)
RE: Carb question
There are several different designs in carbs and this is what you are beginning to notice.
There is the kind that has a tube that's attached to the needle valve side of the carb. It extends half way accross the venturi. The low speed needle at full throttle stands away from this tube about 1/16". As you close the throttle, the low speed rod or needle will go inside the tube and restrict the fuel flow.
There's another kind That has the tube going all the way across the venturi. If you look up inside the carb from the bottom side, with the throttle wide open, you will see the low speed needle extends half way into a eyebrow type cut out in the bottom side of the tube.
There is a third kind that you rarely see but the tube is adjusted in and out by the low speed mixture screw and the little rod is fixed. This type has both the low speed and high speed mixture screws on the same side of the carb.
Then there are the air bleed carbs like on the Thunder Tiger GP series engines. On the front of the carb on the OS trainer type bushing engines there is a little hole. The idle mixture screw extends half way across this hole. This lets air into the carb at idle. This screw works backwards from the other types. To screw the screw in will richen the mixture and to screw it out will lean out the idle mixture.
Enjoy,
Jim
There is the kind that has a tube that's attached to the needle valve side of the carb. It extends half way accross the venturi. The low speed needle at full throttle stands away from this tube about 1/16". As you close the throttle, the low speed rod or needle will go inside the tube and restrict the fuel flow.
There's another kind That has the tube going all the way across the venturi. If you look up inside the carb from the bottom side, with the throttle wide open, you will see the low speed needle extends half way into a eyebrow type cut out in the bottom side of the tube.
There is a third kind that you rarely see but the tube is adjusted in and out by the low speed mixture screw and the little rod is fixed. This type has both the low speed and high speed mixture screws on the same side of the carb.
Then there are the air bleed carbs like on the Thunder Tiger GP series engines. On the front of the carb on the OS trainer type bushing engines there is a little hole. The idle mixture screw extends half way across this hole. This lets air into the carb at idle. This screw works backwards from the other types. To screw the screw in will richen the mixture and to screw it out will lean out the idle mixture.
Enjoy,
Jim
09-10-2003 | 11:58 AM
#3
RE: Carb question
Hi!
All glowengine carbs work the same! They have an idle adjustment (needle or brasstube)that governs the amount of fuel comming inte the carb.
There is one exception to this and this is the cheaper engines that uses the air-bleed type carb were the incomming air is controlled...not the fuel!
Regards!
Jan K
Sweden
All glowengine carbs work the same! They have an idle adjustment (needle or brasstube)that governs the amount of fuel comming inte the carb.
There is one exception to this and this is the cheaper engines that uses the air-bleed type carb were the incomming air is controlled...not the fuel!
Regards!
Jan K
Sweden
