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#1064631 - 01/01/20 02:13 AM throttle return spring  
Joined: Jan 2008
Posts: 1,200
FinallySS Offline
10+ Year
FinallySS  Offline
10+ Year
Member

Joined: Jan 2008
Posts: 1,200
Nice Sunny Hawaii
Aloha guys,

Recently, I have problem with my Eddy carb, namely return spring location.

I have idle compensator on my Eddy carb due to usage of my AC all year around and because of this, I have my return spring on the firewall side of the carb. Recently, I been having problem that butterfly not returning completely and whenever i come to stop, I need to blip my gas pedal for the idle to return. I have read on the net that I should have my return spring on the radiator side of the carb. Sound easy, right?

Well, as I mentioned before, I have idle compensator installed om my carb, so hooking up the spring on radiator side of the carb is bit tricky. See pictures below. Anybody have any good idea how I can hook up my spring? Help!

[Linked Image]
[Linked Image]


1986 Silver MCSS - Poly bushing and Hotchkis spring w/Bilstein, Posi w/3.73, MSD 6-AL, E-Brock 600cfm, Aluminum 2-row radiator.
1986 Black MCSS - R.I.P............Finally.
#1064637 - 01/01/20 05:23 PM Re: throttle return spring [Re: FinallySS]  
Joined: Dec 2002
Posts: 167
PETER86SS Offline
15+ Year
PETER86SS  Offline
15+ Year
Member

Joined: Dec 2002
Posts: 167
Cleveland, TN
Changing the spring position is treating a symptom and not fixing the problem.

If the setup you have has been working for years and this is a recent problem the spring position is only a minor part of the issue.

The throttle blade shaft or the bore in the throttle body that shaft goes through could be worn / dirty - the blades could be hanging up in the bore due to carbon buildup or debris - the throttle linkage on the carb may be hanging up due to dirt / corrosion - the throttle cable may also be causing this. If you can duplicate the symptom with engine off, air cleaner off, as you have it in your pictures, you'll be on the way to figuring this out. With engine off have a helper press the gas pedal, then release it while you are looking at the linkage to see what it does. This way you can see if the linkage fully returns to the curb idle screw. If it hangs up as you've described then disconnect the throttle cable and open the throttle by hand, then release it to see if it fully returns to curb idle screw. If it hangs up without the cable on it that takes the cable out of equation. There is not much external linkage on this carb, looks like accelerator pump only, so you could disconnect that to eliminate it from the mechanical action, then open and close the throttle to see if it still hangs up. If it seats to base idle screw you've found the cause - if it does not it's going to be the throttle shaft, throttle blades, or throttle body. There's no picture of the right side of the carb, if there is mechanical linkage to the secondaries on that side then that has to be looked at too for any binding issues. At this point you'll have to pull the carb off and disassemble it to inspect these the throttle shaft / throttle body for wear or carbon/dirt buildup.

If the throttle returns to the base idle screw with no problems with the engine off, and this symptom only occurs with the engine running then I'm thinking you definitely have a throttle shaft / throttle body wear issue. Manifold vacuum exerts force on the throttle blades when closed, vacuum is at it's highest when you lift throttle, and the throttle blade / shaft assy may be being pulled into a wear area - this will put the shaft off center and the butterflys (round throttle blades) will contact the airflow bore in the throttle body and hang up. When you blip the throttle manifold vacuum drops quickly, this would allow the throttle shaft to recenter and go to curb idle. Putting the return spring on the top of the throttle linkage pulls the throttle shaft forward which would take it out of the wear area - the spring in the stock position pulls the throttle shaft backwards. The bore in the throttle body that the throttle shaft goes through wears every time you open and close the throttle, so I believe your going to find your problem there. Looks like that carb will have to come off for a good inspection.

#1064639 - 01/02/20 02:09 AM Re: throttle return spring [Re: FinallySS]  
Joined: Dec 1999
Posts: 11,911
86ttop Offline
20+ Year
86ttop  Offline
20+ Year
Member

Joined: Dec 1999
Posts: 11,911
Brooksville, Fl
are you using a double spring, that looks like too short of a distance to get good return pull on the spring!


Leo Paugh
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POW*MIA
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#1064649 - 01/03/20 01:22 AM Re: throttle return spring [Re: 86ttop]  
Joined: Jan 2008
Posts: 1,200
FinallySS Offline
10+ Year
FinallySS  Offline
10+ Year
Member

Joined: Jan 2008
Posts: 1,200
Nice Sunny Hawaii
Originally Posted by 86ttop
are you using a double spring, that looks like too short of a distance to get good return pull on the spring!


Yeah, spring is double. Too short of distance? It feels pretty tight as of now, but then again, I may be used to that Fly-By-Wire throttle and gas pedal on my Lincoln LS, which is so light I always press it too hard after I drive my SS.

Peter86SS, I only remove the air filter to take pictures. It does it even when the engine is off. Ever so little, the butterfly does move. What I mean is I can move it with my fingers to original position. And carb is rebuild recently. And just to be clear, I also have Japanese crotch rocket and I do rebuild these carbs on my own. Believe me, it's a chore all by itself trying to rebuild four of these carbs and sync them.

Yeah, I may be old, but still enjoy riding the crotch rockets once in a while!


1986 Silver MCSS - Poly bushing and Hotchkis spring w/Bilstein, Posi w/3.73, MSD 6-AL, E-Brock 600cfm, Aluminum 2-row radiator.
1986 Black MCSS - R.I.P............Finally.

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