Carburetor return spring? - Team Camaro Tech
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post #1 of 13 (permalink) Old Jun 17th, 14, 12:59 AM Thread Starter
Vick
 
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Carburetor return spring?

Why is it when we install the carburetor /Holley/, it needs a return spring, but when it's just sitting on our desk everything works just fine and it returns without hesitation?

I disconnected my throttle linkage and it still didn't return all the way. But when I took the carburetor off it worked perfectly. The guy at the shop said they all need a return spring. But what the heck? Installed or not, shouldn't make a difference with it returning. So, what changes when it's installed? Shouldn't it work properly without a return spring?
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post #2 of 13 (permalink) Old Jun 17th, 14, 01:57 AM
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George
 
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Re: Carburetor return spring?

When you torque your Carb down its probably twisting and binding the throttle shaft undo the 4 nuts and nip them up going opposite sides not too tight. or its touching somewhere as you tighten it.
Yes, run the return spring .
just imagine driving down the road getting on the throttle and it sticks flat out!!

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post #3 of 13 (permalink) Old Jun 17th, 14, 05:21 AM
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kevin
 
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Re: Carburetor return spring?

maybe I am paranoid, but I use 2 springs
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post #4 of 13 (permalink) Old Jun 17th, 14, 05:28 AM
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Re: Carburetor return spring?

Quote:
Originally Posted by flat tire View Post
maybe I am paranoid, but I use 2 springs
I don't think you're paranoid Kevin, you must just like to always have at least a plan A and a plan B and I get that

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post #5 of 13 (permalink) Old Jun 17th, 14, 06:09 AM
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Re: Carburetor return spring?

Definitely two springs. I like the one smaller one bigger that go inside each other. Summit makes some nice ones for cheap and in colors.
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post #6 of 13 (permalink) Old Jun 17th, 14, 06:11 AM
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Re: Carburetor return spring?

Quote:
Originally Posted by flat tire View Post
maybe I am paranoid, but I use 2 springs
X2

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post #7 of 13 (permalink) Old Jun 17th, 14, 06:45 AM
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Re: Carburetor return spring?

The reason why GM went to 2 springs was for safety, just incase 1 breaks. Without a spring the flaps could stay open but it won't return as fast without a spring.

Mark 70 Z28 M22 3.73 Z21 Z87 - Lunati 20120121 Roller Cam

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post #8 of 13 (permalink) Old Jun 17th, 14, 07:34 AM
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Mike
 
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Re: Carburetor return spring?

It could be the gasket (if your running a 4 hole gasket) barely touching one of the throttle blades. I always run two springs as well.

Mike


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post #9 of 13 (permalink) Old Jun 17th, 14, 08:52 AM
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Re: Carburetor return spring?

If the throttle won't return all the way when the carb is bolted to the manifold with or without the throttle arm attached, don't install a return spring to solve the problem. You've gotten some trouble shooting tips already, start by loosening the 4 mounting bolts a little. If that solves the return problem you most likely have a warped throttle plate but check the to see if the gasket between the manifold and carb base is interfering with the throttle blades.

The throttle return spring is a safety device. As you know the throttle will/should close by itself. Without the return spring the foot pedal is going to be very light under your foot and possibly cause erratic and sudden hard acceleration. As well the engine is a big air pump and without the return spring the air being pulled through the carb could cause the throttle to close slower than desired. Lastly the weight and leverage of the throttle linkage could also create more drag causing the throttle to not close as quickly as desired. As you can see that return spring is rather important but again it is not there to force the throttle closed when it won't on it's own!

To my knowledge the factory didn't use double springs on a 1st gen, it was just a single spring that ran back to the base of the coil mount. You don't want the spring so tight (strong) that it puts extra wear on the throttle shafts. A lot of aftermarket springs are designed to be used in pairs, I use a double spring but only because it's what was available when I replaced what was on the car when I got it.

Quote:
Originally Posted by vickcamaro68 View Post
Why is it when we install the carburetor /Holley/, it needs a return spring, but when it's just sitting on our desk everything works just fine and it returns without hesitation?

I disconnected my throttle linkage and it still didn't return all the way. But when I took the carburetor off it worked perfectly. The guy at the shop said they all need a return spring. But what the heck? Installed or not, shouldn't make a difference with it returning. So, what changes when it's installed? Shouldn't it work properly without a return spring?

...Dennis

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post #10 of 13 (permalink) Old Jun 17th, 14, 09:02 AM
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Re: Carburetor return spring?

If you have a choke make sure that the linkage is on right, I had mine on wrong and the car would not idle down.
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post #11 of 13 (permalink) Old Jun 17th, 14, 05:40 PM
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Re: Carburetor return spring?

Dennis sums everything up really well
2 springs is , well in this country a requirement to scrutineering specs on the track...safety thing.
And caution adding springs.. having strong springs causes excessive wear, and even worse, elliptical wear on the butterfly shaft bores.
Note how the carb springs circle the shaft, spins it, no sideways wear.....but the external spring is hooked as a lever....So if adding duel springs, if possible have them very light and pulling from opposite sides top and bottom.

My Spelling is not incorrect...it is creative

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post #12 of 13 (permalink) Old Jun 19th, 14, 12:07 AM Thread Starter
Vick
 
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Re: Carburetor return spring?

Thanks for all the replies. I checked the car again today. When the engine is off, the throttle returns nicely, no issues. When the engine is running, that's when I "run" into the problem of a sticky throttle. Will try to work on the car this weekend and will let you know what did I come up with :-) Thanks again
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post #13 of 13 (permalink) Old Jun 19th, 14, 08:29 AM
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Re: Carburetor return spring?

Quote:
Originally Posted by vickcamaro68 View Post
Thanks for all the replies. I checked the car again today. When the engine is off, the throttle returns nicely, no issues. When the engine is running, that's when I "run" into the problem of a sticky throttle. Will try to work on the car this weekend and will let you know what did I come up with :-) Thanks again
Now that you have clarified the problem I believe I can tell you what is happening because it sounds like I just had the same issue with a new Holley 650.

My issue was the throttle would not idle down completely, sometimes I could blip the throttle to get the throttle blades to close and bring the idle down. From under the hood you could physically see the linkage was not coming to rest on the idle adjustment screw...

The answer was to pull the carb, loosen the screws that secure the primary throttle blades to the throttle shaft, work the throttle a couple times and then re-tighten the screws. Problem solved, I had heard of this before but wasn't putting 2+2 together and just happened to read a thread where someone suggested the fix to another here and that set the bulb off in my head.

...Dennis

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