Thanks for the information. I looked at Mother Truckers set up...I don’t think it would work for me based on the lack of clearance behind the exhaust and the block. The spring would not have the space needed...my exhaust is nearly touching the block.
I tired turning about the bell crank and running the spring back to the petcock....this did not work and the throttle would close appropriately
Grease Monkey, Moderator General Truck Talk & Greasy Spoon
It’s nothing special, just a spring like you show with another smaller spring inside it giving a little more pull.
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This is how the spring is supposed to be installed. Also, Your spring is not the right spring so it may not have the correct tension. You may also need an additional spring as I mentioned, on the vertical throttle rod. Fenton use to make linkage for their intakes that had the tab already welded, to assist with the upper linkage rod.
Others have mentioned a spring for each carb. That works but if you are using the straight unadjustable rod and tab style linkage (like the offy intakes use) the carbs have to be set exactly the same in terms of throttle arm opening/position or they may not close, especially if one carb is open a bit more then the other. You need some independent adjustment for each carb and a tiny bit of slop in the linkage. Also, it’s easier to synchronize the carbs if they can be independently adjusted.
IMO a properly engineered linkage only requires 1 spring near the bellcrank regardless of 2,3, or 5 carbs. If you need more you are trying to hide shortcomings and stressing out the throttle shafts. Anybody see a spring in my setup?
I don't have a picture of that area but there is nothing custom about it. Mine looks like the pictures posted by Phak...there's a tab on the vertical rod for one end of the spring and another tab on an oil pan bolt for the other end. Good luck.
This thread sure reminds me of the struggles I had trying to make a rigid linkage work. It kept me awake at night until the following criteria came to me when designing a solution.
My food for thought on this is specific to multiple rochesters on a Stovebolt and not other applications.
1. The accelerator return spring would ONLY have that function and have NO influence on the carburetors whatsoever.
2. The only pressure on the carbs idle stop screw would come from the internal pump spring and free from influence from an external spring, bolt, or other means. The linkage should lift it just as your finger would with no stress.
Accomplish these goals and it’s a zero maintenance item.