Marvel Air Valve Spring

30essex

I have another question about the 1930 Essex carburator, Marvel "V". The air valve spring appears to be about 1/4 in. too long and the air screw is about 4 turns further out than it should be for the car to run. According to the book this spring should be 1 1/16 in. and it is 1 5/16 in.



"Two types of springs have been used, one has a number of closed coils at the center and is zinc plated. The other type does not have closed coils at the center, but all coils are wound equally spaced. The type of spring having closed coils at the center should have a free length of 1½" while the other type should have a free length of 1-1/16". Air valve springs, for Marvel carburetors should never be stretched under any consideration. The spring is balanced to exert a certain tension at the different range positions of the air valve and distorting the spring in any manner whatsoever will upset this balance and make the correct operation of the carburetor impossible."

ESSEX 1925-1930 Motor Tune-Up & Specifications



Should I cut it shorter, leave it, or try to get a new one?

Geoff

I would go to a hardware store and get several springs of differing tensions, and experiment with the length. Sounds random I know, but wiht a bit of fiddling you will eventually get one that works. Generally speaking, a stronger spring will give a rich mixture, and a weak will cause popping back i9n the carburettor, and weak mixture, with too much air getting thourng. howeve,r it is a delicate balance. Good luck,

Geoff.

Unknown

30essex wrote:

I have another question about the 1930 Essex carburator, Marvel "V". The air valve spring appears to be about 1/4 in. too long and the air screw is about 4 turns further out than it should be for the car to run. According to the book this spring should be 1 1/16 in. and it is 1 5/16 in.



"Two types of springs have been used, one has a number of closed coils at the center and is zinc plated. The other type does not have closed coils at the center, but all coils are wound equally spaced. The type of spring having closed coils at the center should have a free length of 1½" while the other type should have a free length of 1-1/16". Air valve springs, for Marvel carburetors should never be stretched under any consideration. The spring is balanced to exert a certain tension at the different range positions of the air valve and distorting the spring in any manner whatsoever will upset this balance and make the correct operation of the carburetor impossible."

ESSEX 1925-1930 Motor Tune-Up & Specifications



Should I cut it shorter, leave it, or try to get a new one?

Try this guy for Marvel Carb. parts. Ron



http://www.classiccar.com/forums/showthread.php?t=14815&highlight=marvel+carb+parts

30essex

What happens if I cut 1/4 in. off. I'ts obviously been stretched but seems to have the right tension since the engine seems to run fine although it uses a lot of gas.

Geoff

You will most likely upset the balance of the spring by shortening it. If the engine runs fine, you need to pay attention to the float level and jet size, rather than the spring tension.

30essex

Thanks again, Geoff. I adjusted the float as you suggested. I don't know what to do to check the jet sizes. Do you have that information?

awca12a

I ran into a guy at Hershey that had a batch made-up so I bought what he had left. Haven't had a chance to try it out but it looks right and he said it solved his problem. Send me an e-mail offline if you need one.

erbpartners@gmail.com



David