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Username Post: Carburetor return spring        (Topic#351960)
junky 
Valued Contributor
Posts: 2717

Loc: Northeast CT
Reg: 06-27-10
07-10-18 11:09 AM - Post#2739572    

The spring on my carburetor that pulls the throttle closed when you let your foot off the accelerator, isn't strong enough to pull it back fully. What is the correct spring for this application. 327 Cubic Inch engine 300 HP with a Carter AFB. I do have the throttle return check valve properly adjusted, however, it appears that the car needs a stronger spring.
One other thing about this AFB, is that when the engine is cold, the fast idle is what I believe to be too fast. Once it warms up, a quick tap of the accelerator will cause the engine to drop back to the normal idle. It is just the high idle that I can't find an adjustment for. The carburetor was rebuilt by a highly recommended rebuilder.

Never argue with an idiot. He'll drag you down to his level, then beat you with experience.


 




Mercedes 
Contributor
Posts: 189

Reg: 07-09-18
07-10-18 12:02 PM - Post#2739580    
    In response to junky

Disconnect the throttle and see if the throttle blades close on their own. The springs on the throttle shaft should keep things closed. The return spring is designed to give the throttle a bit of feel and return.

My guess is that the springs on the carburetor are not set correctly.



 
55Brodie 
Contributor
Posts: 220
55Brodie
Age: 66
Loc: Little River, SC
Reg: 12-26-15
07-10-18 01:02 PM - Post#2739595    
    In response to junky

The fasr idle screw is below the linkage on the driver's side and rides on the fast idle cam which is connected to the choke plate via a small round bent rod. The check valve is called a dashpot. How do you know it is adjusted correctly? Were the throttle shaft bores bushed during rebuild? They may need honing/reaming. Or maybe your return spring is just tired.



 
junky 
Valued Contributor
Posts: 2717

Loc: Northeast CT
Reg: 06-27-10
07-10-18 02:23 PM - Post#2739597    
    In response to 55Brodie

I set the "dashpot" per the manual. I remembered to look up the instructions, but my memory failed me on the correct nomenclature. I don't know if they bushed the shafts, and I will check to see. The throttle moves smoothly, and I am more inclined to believing that it is the spring is tired. Did Chevrolet use a single spring, or was it a spring inside of an outer spring? This is what I have been thinking of using.
I will also check the high idle cam tomorrow when the car is cold. thanks Junk

Never argue with an idiot. He'll drag you down to his level, then beat you with experience.


 
dgstarr 
"2nd Year" Silver Supporting Member
Posts: 99
dgstarr
Loc: Portland, OR
Reg: 04-16-13
07-10-18 02:42 PM - Post#2739600    
    In response to junky

Junky,

The'62 assy manual shows 3821966 as the part number for a 300 hp, powerglide car throttle return spring. The PG equipped car has a different pn than the manual shift car. Doc Rebuild has these springs on his website for sale.

Dave



 
1963er 
Contributor
Posts: 271
1963er
Age: 68
Loc: Joppa, Md.
Reg: 12-20-15
07-11-18 02:46 AM - Post#2739661    
    In response to dgstarr

I use a spring within another spring. Safety reasons....just saying



 
55Brodie 
Contributor
Posts: 220
55Brodie
Age: 66
Loc: Little River, SC
Reg: 12-26-15
07-11-18 08:50 AM - Post#2739696    
    In response to 1963er

I wear a belt with suspenders.



 
YOUNG57 
Frequent Contributor
Posts: 1071

Loc: Tennessee
Reg: 12-06-10
07-12-18 05:15 PM - Post#2739803    
    In response to 1963er

2X

If your spring is so weak as not to fully close the throttles it may be on the verge of failing or breaking.

The throttles are closed be the throttle return spring. A broken return spring can allow the engine to run uncontrolled at part or full throttle. Using dual springs (spring inside a spring) is just good sense.




 
models916 
Valued Contributor
Posts: 4785

Age: 67
Loc: Addison, IL
Reg: 05-28-10
07-13-18 04:03 AM - Post#2739824    
    In response to YOUNG57

Throttle return spring on the carb is broken. Little spring on the throttle shaft of the carb.



 
Mercedes 
Contributor
Posts: 189

Reg: 07-09-18
07-13-18 05:30 AM - Post#2739831    
    In response to models916

That was my original theory.



 




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