Some basic carb cleaning and rebuild info

[Pawstruck]

Awesome! Thank you!

[dlb]

When you delve into the world of rebuilding carbs you need to INVEST in some Bendix Speedy Clean, cleaning carbs with spray carb cleaner is a real poor method to clean carb parts. speedy clean is an acid that does clean all the small orfices ---air passages--- this product is rather pricey, but WORKS, will remove paint, carbon from anything -------Will REMOVE SKIN FROM YOUR BODY ALSO---- if you rebuild carbs this product is manditory . Larry

Larry, I searched online for Bendix Speedy Clean but couldn't find anything that matches that. Can you post a link to the stuff? I'm very interested.

[NWMO]

Hey David,

Larry hasn’t been on the site in nearly six months unfortunately. I have used Berryman Chen Dip in the past and found it to work well. Again, if you’re “kitting” the carb, it tears down so that everything is available to spray, etc.

https://www.autozone.com/fuel-and-engin ... lsrc=aw.ds

Don’t forget the tools for cleaning/clearing the small holes, etc.

https://www.acehardware.com/departments ... lsrc=aw.ds

Chris

[dlb]

Nice, thanks Chris. I'll look into those.

I know Larry hasn't been on the site in a bit but I thought by quoting him he might get a notification and come check in. Your info is just as helpful though.

[Paul]

The power valve/piston deserves close attention. The main source of fuel to the primary ventury is the primary main jet. Ideally, this jet supplies enough fuel at cruising speed for proper air/fuel mixture, with a little extra for correction by the EBCV air bleeds. As we squeeze the pedal, more fuel is required. This is where the power valve begins to open, making more fuel available to that same primary ventury.
Make sure the piston and it's bore are clean. Install the retaining washer with the curved portion hanging over into the float bowl side as pictured in the FSM... it should just catch the edge of the piston and allow it to sit flush with gasket side of the air horn. This is the "active" position of the power piston, where the piston rod contacts and opens the power valve below. High manifold vacuum during idle and cruising pulls the piston up against spring pressure - into the "inactve" position where the power valve below is closed. Pretty basic for the experienced, but critical wisdom for those new to carb tinkering.

powerpiston.jpg

Here's something to think about. For awhile I've been having trouble with rough part throttle operation. I rebuilt the carb, looked for and corrected small vacuum leaks, verified vacuum line routing, and checked for leaky diaphragms. Every time I thought I found something, I would put it back together and have that same rough running experience. I finally hooked a meter to the oxygen sensor (new), and could see the lean condition. As I studied the carb circuit diagram, I kept thinking about the power valve. I opened the carb again and pulled out the piston and spring. Maybe the spring is tired out after 30 plus years of action? I carefully stretched the spring to help force the piston into the "active" position more often. When i put it back together, the difference was significant. The rough running was almost eliminated, and the oxgen sensor voltage finally showed better readings into the rich range as the throttle was opened under load. The next thing to try (if i can find it) is a new power piston spring, part number 21734.

[NWMO]

Thank you for sharing.

Chrid