Date: Thu, 12 Dec 1996 17:01:45 -0800 (PST) From: Mike West Subject: Port 'n Polish Notes These are just notes on the basic techniques and tools and so on and drivel. You are going to cut some chamfers and grind out some rough spots. Deburr and rough polish etc. Power tools: the 3/8 drill I used is a good choice, turns maybe a little slow. 1200 rpm. 1800 might have been a bit better. The burr, thats the cutting tool on the end of a shaft, was a 1/4" steel , 2" lg. wouldn't want a longer one, it has an eliptical end. Rotary file would be another name. To chamfer those sharp edges under the seat you have to reach down thru the valve seat at an angle. Mask the seat itself, I used masking tape but I think next time I'll cut some duct tape about 3/8" wide and use that. You're just roughing with this power tool. Get out of there as fast as you can. Let the burr pull you along, it's continually trying to rise out of the metal but if you use it the other way, against the rotation, it's going to grab and sink into the metal. Just a light firm pressure. Take light cuts, not too much pressure. You're not in a hurry, believe me. Don't stab it down in some corner where more than one side will be cutting, it'll grab, twist and may destoy your pretty new heads. After I scared myself a few times and had my rough cutting out of the way, I switched to a Dremel tool. My Dremel is adjustable speed and the best speed seemed to be around 3500rpm for working this aluminum. This has a lot less power than the drill and is a lot easier to control. You see guys in the trade using hi-speed air tools for this stuff. They're pro's. You as an amateur try that and you'll kill something. At first, to smooth up the roughing I'd just done and blend adjacent areas, I used small pink stones. Always as large as would go in the area. Too small a stone will give you a "ripple" or "washboard" affect. No one seems to know what the stones are made of so I'll take a guess that the pink ones are a garnet in a white matrix. Fairly soft and don't clog up with the aluminum too bad. For dressing or removing the aluminum from the pink stones, I just ran them over a grey stone which is harder. I guess the grey ones to be carborandum or aluminum oxide. Didn't use them but if I had, what would I dress them with? I used up a couple of the pink, so get at least two of the sizes you think you'll need. Now you need a couple "bobbins". A short one, with a reduced shaft that will fit in either the Dremel or the drill. 1/8" then it has a 1/4" shank and a tapered spiral that runs down to a 1/8 shank for the "bob" to slip on and screw itself up tight. Then you need a long one to reach way deep. It's six" long and no reduced shank, just 1/4' all the way to the bobbin part. It's too long to be used in the Dremel. The poor little dremel doesn't have bearings that will handle that kind of side load. Now let's talk about the "Bob". It's a sandpaper cartridge that slips on the bobbin of course! There are also "Cratex" bobs, rubber with an abrasive in it and have their own shank. Some are tapered and some are just rolls of sandpaper about 1/2 dia. The word sandpaper is a misnomer. They are garnet on a cloth backing. They come in at least three grits, coarse, medium and fine. I got the most use out of the medium with the coarse doing a fair task of cleaning out the exhaust ports. I used the drill with the long bobbin in the ports, intake and exhaust. Generally the "medium", after the coarse roughed the carbon etc out of the exhaust. The coarse never went into the intake. too rough. Later, I found some 3/8 bobs in the medium and they helped get closer into the corners and crannys. It would be nice to have some 1/4" but I was lucky to find the 3/8". The "fine" grade bob was useless. It immediately clogged with aluminum and did nothing but burnish. When working the combustion chambers, use the short bobbin in the dremel and put a set of used valves in to protect your seats. The corners and tight spots should only be worked by hand. Here's the Secret Relationship: Aluminum cuts with sandpaper just about the same as a good paint does. You will remove just about the same amount of material and achieve the same finish you would on paint. Just like sanding a car, the corners etc. are the hardest. In a head, the corners of the exhaust and combustion chamber should be the smoothest. These are the places where the carbon will have a chance to build up. Also just like a car, power tools are only good for so far, then you go to the hand tools. I finished the inside of my combustion chambers with a piece of 220 emery cloth and my fingers. Then I buffed some with a scotch-brite pad from the kitchen. They look real good. If you want shinier use some polishing compound on an old t-shirt. I draped a piece of emery over a popsicle stick to get inside under the valve seats and around the valve guides. Save the combustion chambers for last. By then you'll be so freaking bored, you won't be so eager to grind out pounds of metal. Don't forget about "CC'ing" them before you finish them. You really should practice on an old head, doing at least one of each inlets or exhaust and one chamber before you start on that new set of heads. west