Resurfacing Exhaust Ports

[krw5927]

While drilling out an exhaust stud hole for a heli-coil/keensert repair (see earlier thread http://www.vansairforce.com/communit...ad.php?t=95294), I noticed that all four of my O-320's exhaust ports have a rough, uneven surface. Some are worse than others, of course, but all could use some attention. I'm afraid that their current condition is evidence of past exhaust leaks and really don't want to slam another gasket up with a brand new Vetterman exhaust just to have it leak as well.

I've done some reading about tools to grind or lap the exhaust port surface, but wondered if anyone had experience or advice on the process. Also is it possible to rent/borrow tools to do this? Spruce sells one such beast, but it's terribly expensive and requires purchase of a special mounting bracket as well for a total approaching $600

http://www.aircraftspruce.com/catalo...surfactool.php

Any and all advice is appreciated - thanks!

[aerhed]

I have done it with a file. That's the slowest way I know of. Faster is a die grinder with a fiber wheel that covers the whole port , but doesn't hit the fins. This works if you don't have to go deep. The challenge is staying square. Of course you have to pull studs first. Slip something in to guard the fins too.