I am building an engine for gn racing. I had a problem with valve to piston clearance on the exhaust side. I advanced the crank sprocket 4 degrees and the clearances came into acceptable at .110 on exhaust side and .070 on intake. cam is an Isky 747d 288 292 @.050 on 107 lobe center. My question is: Is this an acceptable fix or is performance going to suffer. The cam already has 3 degrees of advance built in and I just added 2 more for total of 5 degrees advanced.