Nope I use a ball point pen. Sounds kind of stupid but I've seen a 15-20 cfm gain by positioning the pen in different parts of the port to show obstructions or deflections, then make the corrections needed. I did this on the 344/349 engine and those heads flow 212 @ .400 lift on the intake and 198 on the exhaust with 1.78 and 1.60 valves. But because of the cam design the engine will think that the heads are flowing near 300 cfm's. These heads flow 190 @ .300 lift on the intake side. The cam is only .473/.492 lift but the duration @ .050 is 274/270 with a 106 CL. The lobe looks almost square like a roller but it's a hyd. cam. The way this cam works is that a few degrees past TDC the valve opens .150 and stays there for about a 1/4 of the duration then it opens to full lift for a short period and then drops back down to .150 then closes and fires. Dang I must have misplaced the specs..