Technical GM dual throttle return spring question

What is the reason for the dual throttle return springs on the 60s and 70s GM engines? Where there is a large outer spring with a smaller inner spring. Is this just a safety feature in case one of the Springs breaks?

 

I think so.

Sent from my Trimline

 

I assume so, 2 return springs are required for many sanctioning bodies for racing as well.

 

I had a factory spring where one wire was folded in half, then the double strands were wound into the return spring.
Safety inspector tried to say it was not double. It removed it so he could see the two strands up close.

 

Just guessing but I'll bet it had more to do with spring rate , as the springs were different shapes & wire sizes ...

 

Backup spring, a very good asset.

 

I used to do safety inspections. It is written in our vehicle standards act. Yes for safety reasons in case one breaks. I'm sure other jurisdictions have different regulations though.

 

I was a inspecter for nsra and dual throttle springs were mandintory.

 

SCTA-BNI was the same. But some inspectors had a funny way of counting. You could have ten springs and count each one and some of them would want one more. By the way shaft springs never counted even if they were on each side....

 

Thought that was a D.O.T. thing, not sure what year it started.

 

I too was on a NSRA safety inspection team, that's something they look for, it is a safety feature if a spring was to brake the other will keep the throttle from going past center is what I remember as the reason for the 2 springs. HRP

 

Yep still in the book. One inspector was wearing a guy out about not having a spring one day.
Was able to show the lead inspector how recognize a GM throttle body. Late eighties vintage.

 

Cheap insurance.

 

Holleys have a primary spring that are wound up over the throttle shafts...

 

Not countable with racing organize ran with even though I’ve shown the inspectors that with all other springs removed and the throttle rod or cable attached or not, at wide open throttle held by hand, let go, the butterflies slam shut.... still a no go. 2 additional springs or go home.