Dartin for Divorce

May I recommend you measure the deepest point into whatever you need to port (heads, manifolds, etc), then cut the excess off of your long-stem carbide burrs. I think you will find that there is probably 2-3" of excess stem you can cut. When you do this, you shorten the problem; the bit will be less likely to snag & bend. I modified practically every long-stem burr I ever bought to maximize physics.