Throttle shaft

[Arronh]

Hello. I have a 68 200 (20hp). It’s dripping some gas from the throttle shaft. I took apart the carb. There’s no o-ring or anything to prevent fuel from leaking down the shaft, and there’s a bit of play in the shaft. How can I prevent fuel from leaking down there?

Also, I have this set to the lowest tilt lock position while working on it in my shop in a barrel of water. At this position it leans a bit forward. It runs well at idle, but when I shut it off, it drips a bit of fuel from the from of the carb body. I haven’t seen this from any of my other carbs.

Are the two issues related? The float valve seems to work as it passes the blow test. At low idle the gas seems to seep up from the tube in the middle. At high idle it starts to spray more.

Thanks

 

[Chris1956]

Both symptoms point to an overflowing carb. Make sure the carb float is set correctly. Replacement of the carb inlet needle valve and seat is a maintenance item, as is replacement of the float.

Also, the motors in the 70's had foam floats that dissolved in today's alcohol fuel mix. Those foam floats were replaced with hard plastic ones. Those can crack and leak fuel inside them.

 

[Arronh]

Thanks. I’ll order a needle valve and float.

Regardless of the overflow condition, should I be concerned at all that gas can even go down the throttle shaft, or is that normal?

 

[racerone]

Fuel cannot leak from that shaft when motor is running.----Normal to leak from throttle shaft right after motor is stopped.

 

[Arronh]

How much pressure should an inlet needle valve be able to hold? I have a pressure tester, so I might as well take a look.

 

[Arronh]

Also, I’m going to pressure test the lower unit. How much pressure should that hold and for how long? I’m just wanting to test as much as possible before loading the parts cannon

 

[Arronh]

I got a tachometer sensor today. Anyone know what the recommended low idle rpm is in addition to the previous questions I posted?

 

[Chris1956]

Once you synch the carb opening and ign timing, set the idle speed to whatever runs slow and smooth.