View Full Version : Schebler H airvalve tension

T. Cotten
04-16-2008, 08:14 AM
Tommo and others have cited 5 ounces of tension for the airvalve, and this is easily accomplished with a new spring on a 1 1/4" model.

However, the 1" and 3/4" models have a weaker spring.
Can anyone tell me the proper tension for these smaller carbs?

Thanks in advance,

Rod K
04-17-2008, 10:32 PM
Cotton: I have been watching your post with interest. I need the spring tension info for a 3/4" Schebler, on a 1912 HD. I copied a picture of your devise, to measure spring tension.
There must be someone out there who knows................Rod

04-18-2008, 03:27 PM
This will be of no help but I have a Schebler book that goes from 1921 back. Regarding the spring tension as stated in the book: "The air valve spring does not werar out but they do get out of shape. There is no set rule about using new springs. On factory repairs we always use a new one to be sure of getting the best results. If a new one (spring) is used be sure to get the proper one as shown in the equipment list. Set the spring with the large end against the air valve disc and screw the retainer nut onto the stem until it is the exact distance you measured before it was dorn down.

I told you it would be of no help. I guess Schebler was protecting their proprietary secrets because they state in a number of places not to use "Pirate Parts" as they called them.

T. Cotten
04-18-2008, 10:11 PM
My 'pirate' replacement springs were made by Fickau Prototypes to produce the same tension as NOS originals.

(I have a bag of fifty of both sizes; Will trade for other Schebler hardware!)

Thank Gawd they are adjustable.


05-10-2008, 11:07 PM
I am rebuilding an HX181 and have never run one. I am under the impression we need to be able to adjust the tension to tune the carb to the motor? More tension keeps the valve seated longer, and so more air is brought through the bottom air passage. Adjusting the tension is another piece of the mixuture equation?

05-11-2008, 12:06 PM
Hello: I too have been watching this thread with interest. In atmospheric intake engines doesn't the intake spring pressure have a bearing on the flapper spring pressure? In 3/4 inch
Schebler bastard applications such as Shaw its trial and error. Also the engine has to be retuned after it warms up. There have been times I've unscrewed the whole flapper off the carb and stuck it in my pocket after I got the engine warm. Sometimes it works, sometimes not. There was an article done years ago by a club founder titled "How a poor man can adjust a rich carb" or something like that. Really helpful. I've got a photo copy around here somewhere. Great fun.
John Hasty