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Old 12-05-2011, 12:31 AM
charlief1 charlief1 is offline
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Default Re: Rochester Carb Adjustment

That's a 2GC carb and they're pretty easy to work on. If fuel is coming out of the top then the float and or needle are needing replacemment. My guess is that it's a 225 or 231 oddfire engine. The 231 was made of about 3 years as an oddfire then changed to even fire in 77 & 1/2. Does it have points or electronic ignition?

As far as the adjustments, my guess is that it has a heat pipe going to the choke. If that's the case you can replace the plastic choke thermostat with an electric one. It will work much better than the original one and they aren't that expensive.

To adjust the idle speed/mixture you need to have the engine at operating temp first. Then see what idle speed you have. If you have to reduce spring pressure on the choke thermostat do it. Then adjust the timing first. Then on the side of the carb adjust the idle speed. Once you get the speed to about 600 RPM then you need to adjust the mixture screws. A tach is the best way to do it. You're watching for a change in the RPM level, either up or down. You want the speed to go up as high as you can get it as you screw the screws out, then look for about a 50 to 100 RPM drop. Do one first and then the other. At this point I usually go sniff the tail pipe and see if it smells rich or clean. If it's rich screw the adjusters in very slightly on both sides and check the tail pipe again.

If this is clear as mud, sorry, but this is the basic procedure to do it.
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