When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Switched the return springs for the throttle linkage on my 770 Holley Street Avenger that's on my '72 U code Supreme. I made the change for aethstetic reasons, and I noticed that the old upper spring pictured below was attached to some sort of secondary linkage. It didn't appear to have any purpose other than another place for a spring, but am I correct?
Before
..and after I made the swap
And here's a closer view of the mechanism in question...it's where the big upper spring attaches just above the and behind the smaller spring attached to the linkage.
As I said, removing that upper spring seemed to have had no affect on proper operation of the carb, because after the swap to the other springs and a
"shakedown" test drive, all was good.
It’s a secondary throttle return spring. Many times the smaller spring is routed inside the larger spring. Doesn’t really make a difference in operation.
The linkage the large spring is connected to is for Chrysler/Ford kickdown cables or linkage. It serves no purpose on a GM application.
Put the smaller spring thru the larger spring, then put them on the same mounting holes.
^^^THIS. The reason why there are two different diameter springs is that they are intended to be mounted concentrically. There are two as a backup in case one breaks. Your throttle will still close. And yes, the black spring below the carb in the second photo does the same thing, but again you should use two springs, not just one. I've found that those aftermarket concentric springs are a bit stiff. The OEM springs from a 1980s GM work a lot better in my opinion.
^^^THIS. The reason why there are two different diameter springs is that they are intended to be mounted concentrically. There are two as a backup in case one breaks. Your throttle will still close. And yes, the black spring below the carb in the second photo does the same thing, but again you should use two springs, not just one. I've found that those aftermarket concentric springs are a bit stiff. The OEM springs from a 1980s GM work a lot better in my opinion.
If you look closely, you'll see that there are actually 2 springs...is this what you mean by "concentric" springs Joe?
Yikes. We could really get into a gnarly old conversation (preferably over cocktails) with this type conversation. However, I want to be clear I do understand your logic and reasoning with regards to the CENTER of a circular object - by which you refer to radius as a function of mathematical distance. It is only because some choose to define radius as a construct of mathematics that we define radius as a function of "distance". This is why we are defining concentric very similarly but I choose to remove the inherently unreliable variable of distance. Objects 'spin' about an axis relative to each others radius regardless of their distances to one another. Any concentric object which spins or is defined as a planar concentric circle (object) must share the same radius; if they do not, they are not concentric. Thus again, radius is not a function of distance - radius is the description of a line (ray) from the axis outwards to a focus point on its circumference regardless of distance.
This is getting kinda picky and you make a valid point if you are to consider distance (as an expression of the diameter of a circle). However, in reality the radius of any circular object with a known center is called a line (segment) and has nothing to do with distance - that line is called the radius (from its axis to any focal point contained on its circumference). Again, the radius is a line - nothing more, nothing less - it's a line (it's a ray). Any concentric circle shares the same radius as all other circles contained within - regardless of the distance of the radius (as an expression of mathematics). And, that is why the "radius" is shared among all concentric circles. No circle can be considered concentric to any other circle unless they both share the same radius. It's the mathematical "distance" factor which is misleading here. You can define radius as a function of distance (if you like), but the radius of a circular object (especially a circular object rotating in space [as opposed to a planar circular object] is a line - nothing more, nothing less regardless of its distance.
So, no - each ring in a tree does not have a different radius - they all share the same radius - regardless of the distance of the radius. You are correct, they must share the same center (axis), but they must also share the same radius, if they do not, they are not concentric. An object is not considered concentric if it does not share the same radius as another object. It has nothing to do with distance - it has everything to do with the radius.
Sorry, Dave.
Last edited by Vintage Chief; July 8th, 2021 at 02:49 PM.
July 7th, 2021, 07:40 PM
