2 x 4 Initial Adjustment

[Joe Fisher]

I just rebuilt the carburetors for a 61 set up. Does anybody know what a good starting point would be good for the throttle plate opening? I set them at one turn apiece. Should they be the same? I am talkig about the idle speed adjusting screw.
Thanks.

[Ed Jennings NCRS #1550]

Re: 2 x 4 Initial Adjustment

A little confusing. You refer to "them", implying plural. There is only one idle speed adjusting screw, on the rear carb. That is, of course, unless you have the 56-57E models with the adjusting screws in the base plates. In that case, screw both of these in tight. They were a mistake that was corrected with a service bulletin at first, followed by deletion in later models. The rear screw will probably need to be out a couple of turns, but it is real quick and easy to adjust. If you are refering to the idle mixture screws, they should be open about 1-1/2 turns on both carbs, but you will very possibly end up almost closing them on the front carb.

[Ed Jennings NCRS #1550]

Re: 2 x 4 Initial Adjustment

A little confusing. You refer to "them", implying plural. There is only one idle speed adjusting screw, on the rear carb. That is, of course, unless you have the 56-57E models with the adjusting screws in the base plates. In that case, screw both of these in tight. They were a mistake that was corrected with a service bulletin at first, followed by deletion in later models. The rear screw will probably need to be out a couple of turns, but it is real quick and easy to adjust. If you are refering to the idle mixture screws, they should be open about 1-1/2 turns on both carbs, but you will very possibly end up almost closing them on the front carb.

[Joe Fisher]

Re: 2 x 4 Initial Adjustment

Ed,
I was talking about the screws for the throttle plate openning, which controls the idle speed, not the mixture screws.
I looked throught the ST-12 and the 61 shop manual, but thee is no reference to this setting.
The reason I have to reset them is there are a couple of adjustments that you have to back off the screw to allow the throttle plate to close completely.
Thanks

[Joe Fisher]

Re: 2 x 4 Initial Adjustment

Ed,
I was talking about the screws for the throttle plate openning, which controls the idle speed, not the mixture screws.
I looked throught the ST-12 and the 61 shop manual, but thee is no reference to this setting.
The reason I have to reset them is there are a couple of adjustments that you have to back off the screw to allow the throttle plate to close completely.
Thanks

[Ed Jennings NCRS #1550]

Re: 2 x 4 Initial Adjustment

You are still in plural mode. Only the rear carb has an idle idle adjusting screw, if my memory serves. I would screw it in 2 or 3 turns just to get the engine started. you can adjust it by ear after the engine is running and the fast idle comes off. Once you get it reasonably well adjusted, you can reset the idle with a tach.

[Ed Jennings NCRS #1550]

Re: 2 x 4 Initial Adjustment

You are still in plural mode. Only the rear carb has an idle idle adjusting screw, if my memory serves. I would screw it in 2 or 3 turns just to get the engine started. you can adjust it by ear after the engine is running and the fast idle comes off. Once you get it reasonably well adjusted, you can reset the idle with a tach.