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Throttle return springs


pleadingbark

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Everything should be free to rotate, especially your linkage. With only the return spring from each carbs, mine are going back off easily.

In addition, I've got an extra spring going from the stock lever arm to the hood lock area.

Other solution I have seen was an extra lever arm on the rod and a spring going to the cam cover with a custom made bracket (a plate with 2 holes - one for the bolt to attach it to the cover, the other one for the spring)

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I've been wondering about this recently. I'm rebuilding a set of 40's right now. The first carb I took apart didn't have the internal return spring, and the second had a broken one binding the movement of the throttle plates. From what I've read online, these breaking and binding things up is not an uncommon problem. Should I bother installing internal springs or go to a pure external setup?

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EVERY CARB NEEDS IT'S INTERNAL RETURN SPRING!

 

You pop off a linkage and have one or two carbs stick at WOT and you will see the importance of this!

 

Lazeum is correct, your linkage from Nissan is an over-center design that uses weight to help return the pedal and linkage to the closed position. The springs in the carbs are your SECONDARY SAFETY to close the carbs should a linkage break.

 

Adding a third spring may be required by some bodies in racing because they don't consider the carb springs adequate as a safety. Really all it does is make the pedal heavier.

 

If you have it set up right, they close fine with just the internal springs, and possibly the crossbar on the linkage connected with the manifold. Internal, crossbar, and overcenter design should be more than enough. Remove one, and you're asking for tragedy IMO.

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