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post #18 of Old 08-16-2012 Thread Starter
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Location: Derry, NH
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Now it starts and runs but won't idle

Huge progress today:

I advanced the rich/lean valve 1/4 turn toward RICH;

I finally understand the throttle linkage and it wasn't engaging the cam on the carb throttle at all; I turned the set screw all the way in and now the linkage just hits it when the throttle is at SLOW. When at START, the throttle is open about 1/4 turn.

At FULL choke it took off like a rocket and I was immediately decreasing the choke and throttle, more like I expected.

The water pump pees nicely and it ran at half throttle for over 10 minutes, so an awful lot of stuff has been qualified.

It won't idle, however. As I walk the throttle down, the engine eventually stalls before the linkage disengages the cam. I'm not sure what idle RPM is and have no way to measure it. It 'seems' like at idle the throttle linkage fully disengages the cam and the carb should maintain the idle on its own.

On a lot of carbs I've seen, there is a set screw the stops the throttle arm just before it hits bottom. There is no such arrangement here.

So, I'm looking at 2 options:

1. Tweak lean/rich (and troubleshoot) to get it to idle with the cam follower completely disengaged.

2. Find out why the throttle linkage disengages the cam so early.

Zen Again

1978 Bristol 29.9 #122

Testing a mother's love since 1962
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