Would a standard port set of tampered and round sandpaper rolls be suffice for this type of job? I believe they are typically 80-100 grit. Plus a short and long mandrel extension.
Before you wreak havoc with a 6" carbide, keep in mind a few things. Most people cut an inch from the shank and observe a careful rule about keeping it's speed and pressure very low as they whip about and jump when they grab material. The slightest deflection coupled with a high rpm slip will bend one to failure and at a minimum wreck the tool, shake your hands pretty good and probably scare you forever from home porting...if you are lucky. For a limited tool investment, I'd skip the long tool entirely and get a couple short ones. Of the 50-60 carbides I have the long one is the least used and in the areas last cut (or never) with a mild port job. They are nice to have though.
I do use a stone grinder but they are hard to get around the valve guides. They don't grab and jump the same as carbide.
The stones are fantastic, esp. for blending where a carbide hogs. They leave a perfectly roughed finish as is. They are also easily dressed down to true up or custom shape. A flame or curved carbide shape with a handful of stones is a great way to go. I usually need two carbides to get around valve guides in most heads due to the guide not being the center of the port, Buick being a bit different though. If the carbide grabs two sides at once, they either stop or bounce harshly (air tool) or shatter and bend the shankwith an electric grinder.
You'll be lucky to remove casting buggers with sandpaper rolls! That kind of stuff is mainly if you want a better finish after using the carbide burs. With cast iron you'll want the burs with the diamond pattern on them because those aren't as grabby or jumpy. The continuous looking multi-blade style are more suited for aluminum. Don't let certain comments scare you, its really not that bad as that worst case scenario that was written. Make sure when you install a shank that it isn't installed bottomed out or it may loosen on you. Install it until it hits the bottom and pull it out slightly around an 1/8", this will allow the shank clearance to move down in the collet as its being tightened. Get the 6" cutter and install in your grinder and measure how long the installed length is, should be 5" to 5 1/2" long in grinder. Now measure how deep you want to cut in your ports and add around an 1/2" for safety margin, now remove the cutter and install a cut off wheel in your grinder and cut the 6" bur to that length and there you go. They go from 3" to 6" because you can cut to whatever length you need in between. If its only an extra 1/2" or so longer than you want to reach plus your safety margin then don't worry about it. Most of the material should be in a ways of the port opening where the pinch point is so you'll need more reach to open those areas more so than the entrance opening. In the entrance opening you'll mainly be taking the most material off of the roof of the port IIRC(its been a while) and further in off of the pinch point. For the opening area you'll want one of the 3" burs for doing the close to the surface work. GL If you have anymore questions, don't hesitate to ask. Derek
