Vintage Oldsmobiles Curved Dash, Limited Touring, Models 40, 53, 66; Series 60, 70, 90

62 Starfire 4gc Carburetor Power Piston

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Old Mar 3, 2019 | 12:42 PM
  #1  
borgerding's Avatar
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From: New Orleans
62 Starfire 4gc Carburetor Power Piston

Hello all, I have a question regarding my 4gc carburetor on my 1962 Starfire.
My carburetor, a Rochester 4gc tag #7020955 incorporates a power piston #7011947 which includes a float assist spring assembly, (see attached image).
Like most power pistons, it also has a spring which inserts into the hole in the power piston end. My main question is if anyone knows the specs for this spring, and where to buy one? The part number I have for the spring is #7011957, but I havnt been able to find one anywhere.
In the attached image, I show a spring which I believe is the correct original one for this power piston, but Im not 100% sure. Im not fully sure because while in the process of rebuilding the carb, and removing the power piston assembly, the spring flew out and onto my shop floor. Coincidentally, I have a drawer full of springs right under my workbench, and over the years, there have been any number of loose springs dropped to the floor in this area. Therefore the power piston spring which flew away and onto the floor had many friends. I picked one up which looked to be the correct one but cant say for sure? This spring is 1.69" long x .19" dia x .013" wire dia.
I rebuilt the carb because Ive been trying to solve an off idle bog/stumble. To rule out the carb as the culprit, I obviously want to make sure its put together and adjusted properly.
Any help would be appreciated.


Old Mar 3, 2019 | 04:33 PM
  #2  
Tedd Thompson's Avatar
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From: Forest Ranch Ca.
You might give these guys a call. I use them for 4gc parts, mostly accelerator pump stuff. With all the numbers you have they should be able to get you the correct part. https://quadrajetparts.com/accelerat...c-104_109.html
Old Mar 3, 2019 | 05:01 PM
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borgerding's Avatar
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Thanks, Ill ck them out
Old Mar 3, 2019 | 06:01 PM
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Ozzie's Avatar
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From: S.E. Louisiana, so far still in U.S.A.
Originally Posted by borgerding
Hello all, I have a question regarding my 4gc carburetor on my 1962 Starfire.
My carburetor, a Rochester 4gc tag #7020955 incorporates a power piston #7011947 which includes a float assist spring assembly, (see attached image).
Like most power pistons, it also has a spring which inserts into the hole in the power piston end. My main question is if anyone knows the specs for this spring, and where to buy one? The part number I have for the spring is #7011957, but I havnt been able to find one anywhere.
In the attached image, I show a spring which I believe is the correct original one for this power piston, but Im not 100% sure. Im not fully sure because while in the process of rebuilding the carb, and removing the power piston assembly, the spring flew out and onto my shop floor. Coincidentally, I have a drawer full of springs right under my workbench, and over the years, there have been any number of loose springs dropped to the floor in this area. Therefore the power piston spring which flew away and onto the floor had many friends. I picked one up which looked to be the correct one but cant say for sure? This spring is 1.69" long x .19" dia x .013" wire dia.
I rebuilt the carb because Ive been trying to solve an off idle bog/stumble. To rule out the carb as the culprit, I obviously want to make sure its put together and adjusted properly.
Any help would be appreciated.
My carburetor book agrees with your part numbers. I'm assuming that the spring is not provided in standard carburetor kits for your carburetor. That off idle bog/stumble might be caused by the accelerator pump. Here's another possibility for parts: http://www.thecarburetorshop.com/PartsRochester.htm
Old Mar 4, 2019 | 01:58 PM
  #5  
borgerding's Avatar
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Posts: 42
From: New Orleans
Thanks,
"The Carburetor Shop" has the spring. Well see if it affects my bog off idle.
Also, I have a new accel. pump in the carb, and it appears to squirt beautifully. The thing that puzzles me about the bog is that it only occurs while driving, not while sitting?
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