Throttle Return Spring Tension - Vintage Mustang Forums
 
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post #1 of 12 (permalink) Old 09-04-2019, 02:55 PM Thread Starter
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Throttle Return Spring Tension

Is there a spec?

Ive got several springs and Im wondering which one to use.

Ive got a set of the dual springs from Summit, one large and one small diameter that fit inside each other. Those have a lot of tension and it seems that your foot will get tired. I thought about using one of those.


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post #2 of 12 (permalink) Old 09-04-2019, 02:57 PM Thread Starter
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Im getting closer, intake, valve covers, carb, dizzy installed, waiting on the last of the AC pulleys, then I should have the engine side of my PS project complete.


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post #3 of 12 (permalink) Old 09-04-2019, 03:10 PM
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It is always a good idea to use two springs for safety. Just get the tension set to how you like it.
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post #4 of 12 (permalink) Old 09-04-2019, 03:26 PM
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I use 2 springs on my Holley and Edelbrock carbs like the dual springs you described, but only run a single spring on my Sniper EFI because it has a substantially stronger spring built into the throttle body.
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'66 GT Fastback, 302, Edelbrock Top End, Sniper EFI/Aeromotive, MSD, JBA Headers & 2.5" Exhaust, T5Z, Currie 3.55 Trac-Loc
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post #5 of 12 (permalink) Old 09-04-2019, 07:29 PM
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Quote:
Originally Posted by cmefly View Post
It is always a good idea to use two springs for safety. Just get the tension set to how you like it.
I never thought about 2 springs for safety. I currently have 1 spring. I'm going to make a note to change my setup to 2 springs. The safety point makes sense to me.
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post #6 of 12 (permalink) Old 09-04-2019, 07:35 PM
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Quote:
Originally Posted by bmcgc View Post
Is there a spec?
Well, in a way... there are part numbers for the 2 springs used in the factory installation as well as the applicable brackets and placement of same....

A lot depends on the carburetor and linkage being used. It isn't necessary to have a ton of tension... you really just need enough to close the throttle in case of failure of the linkage and to overcome anything that could cause "sticking".

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post #7 of 12 (permalink) Old 09-04-2019, 08:29 PM
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It was suggested to me that too much tension acting on only one side of the throttle plates can over time wear the throttle shaft or the cross shaft hole the throttle shaft sits in, inside the carb.
If you do two springs, it'd make sense then to have one spring acting on one side of the throttle linkage, say at the top and pulling to the front of the engine, like say the wire guide on a front valve cover bolt, and the other spring mounted to the bottom of the throttle shaft assembly and pulling to the rear of the engine. That way you get the benefit of two springs each acting to close the throttle ( in case one snaps or whatever), but not acting with twice the strength on only one side of the throttle shaft and risking wear in the throttle bore of the carb.

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post #8 of 12 (permalink) Old 09-05-2019, 09:40 AM
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In many original configurations the spring (singular) actually pulled on the rod between the throttle pedal and the carb, so there was no tension directly on the carburetor itself (but some thru the rod).
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post #9 of 12 (permalink) Old 09-05-2019, 10:16 AM
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When all else fails, revert back to the manufacturer's recommendations. I checked the instructions on numerous Holley carbs and found the same (or similar) solutions for each. The attached image is similar to those I found on nearly every carb they manufacture.
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post #10 of 12 (permalink) Old 09-05-2019, 12:15 PM
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i had the summit spring fir years, too much tension for me

i just took off the larger one and use the smaller one.
still stiff but much better.

or just go to any hardware store and try various springs

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post #11 of 12 (permalink) Old 09-05-2019, 12:16 PM
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Look up one of these:


Lokar SRK-4000 Stainless Steel Carburetor Bracket and Spring

I just ordered one to see how it works. I've dinked around with springs since I've had my car (25+ years) and have never been happy with the feel of the pedal. I took her for a drive over the weekend and I kinda got pissed and searched and found this item - it should be in sometime this week and I plan to install it this weekend. PM me if you want, or if I can remember I'll post back on this thread. This has both springs and attaches on the back drivers side mounting nut for the carb, or at least that is how I saw it connected. I have looked and looked for one that works, presently I have a single spring that attaches to a metal "keep" that is bolted to my intake manifold. I don't have too many places to mount on the intake, and finding a spring that works where I do has obviously been difficult. I think this Lokar thing might be the trick.
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post #12 of 12 (permalink) Old 09-05-2019, 12:19 PM
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Here is a diagram:


https://www.google.com/search?q=Loka...=firefox-b-1-e


Hopefully it works...
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