EXHAUST & DONUTS

You are looking at the CHUCK end of my lathe. The piece in the lathe is the stator from a customer's alternator. The brass colored thingies are called "slip rings". The brushes in the alternator rub continuously against these slip rings and after about a jillion miles, wear grooves in the slip rings. Using this lathe set-up, I carefully cut the slip rings to a smooth surface without the grooves.
This doesn't have a darn thing to do with exhaust systems or donuts, but the lathe is a pretty color, yes? Well....

The deal with a lathe is to make a number of VERY light cuts. Getting heavy handed here can gouge [and ruin] the slip ring. That makes junk out of the whole alternator stator. Not good. A lathe is a great tool, when you know how to use it correctly.

NOW we can talk about exhaust systems and "donuts". On a Saab/Ford V4 engine, the donut fits against the exhaust manifold gasket. I open up the exhaust PORTS to gasket size, so the donut has to be opened up to an inside diameter just a wee bit larger than the gasket. This is the lathe set-up, showing the donut mounted in a special holding tool that I built.

Once again, I make a number of light cuts until I get the inside diameter that I want. You can see a previously cut donut laying on the lathe platform [yellow painted area], right behind the lathe carriage.

You are looking at the RIGHT side of a freshly rebuilt, high performance Saab V4 engine. I'm holding the opened-up donut in my left hand, and the end of an exhaust header pipe and pipe securing flange in my right. You can see that the dount is actually larger--by quite a bit--than the header pipe. This engine will get larger diameter header pipes, part of a big bore high performance exhaust system.