Inliners International Forums General Discussion Engines 261 fouling plugs

I finally got my 261 running, but it fouls plugs after only a few miles. It seems to be dry fouling the plugs (black puffy soot on the plugs). I change the plugs and the engine runs fine until they foul again.

Where do I start looking to fix the problem? What all could it be?

You are running too rich with your carburetor - check to make sure your float level is not too high or that your idle mixture screw is not backed out too far. Jets might also be too big. Some carburetors need a vent to manifold vacuum through the base and in many cases the gasket is not properly cut to provide that vent.

Bottom line - too much fuel and it is going to take some sleuthing to figure it out at the carb.

I thought it might have something to do with the carb, but was not sure where to start. I can handle the mixture screw, but how do I check/adjust the float level? The carb is a 1bbl Roch.

To add to what Ken said, I haven't found a Rochester B yet that didn't have a hangup with the power piston somehow, either a warped casting making the piston sticky or carbon in the bore. Make sure it slides freely and that the ball seats when it retracts. A sticky power valve will make the engine run rich all the time. When the throttle is closed with the engine running vacuum draws it up leaning out the mixture.

A 261 should have a #57 or 58 main jet, if you have a B from a 250 it will be a #62 or 63 which will be too rich.

Dear H-49;

There's no white smoke comming out the tailpipe, right! Just a little black??

John M...

there is some white smoke right when the truck fires up but then it clears up. I think I have decided to change carbs and go with a Holley/Webber two barrel.