I am not sure what exactly you are looking for but I can speak of how mine has worked.
A lawn mower recoil spring is basically a long spring. I have been extremely happy with the feel. Having said that, with the MG I had a lousy feel to the Lokar throttle linkage. Once I changed to a heavier cable it all felt so much better so a good cable is important too.
Mine is not as elegant as others or even as elegant as it could be but it is extremely functional. Bolting to the actual carbs the way I did had another purpose. This is the Ford 400 engine which is a Cleveland with an extra inch of deck height. The heads were further apart. I used a Hal intake but I cut a center section out and split the intake. The spring plate was just an added stabilized support for the Webers. I probably don't need it but I did it that way because I could.
So a question...Maybe PD can answer this, if you track a car typically don't they require more then one return spring?
