15 PLUS Most common mistakes We get lots of phone calls and emails everyday, Here are the most common mistakes done by builders and machinists. Number one is valve guide clearance too tight, the new stainless valves require .002-.003 on intakes and .0025- .0035 on exhaust valves or you will have serious problems. Number two, trying to install hardened seats and ruining the heads, Buick's don't need them. Number  three is leaving out the oil galley plug in front of the distributor on the end of the oil galley that stops inside the block, loosing oil pressure. Number four is bolting the flywheel/flexplate on wrong causing the engine to be out of balance, ALL Buick's are externally balanced, line up the index hole. Number five is buying a cam designed for a Chevy engine,all the camshaft companies just want to sell what they have in stock, you could easily loose 100hp!. Number six, not degreeing a H.P. cam in, ALL custom camshaft grinds must be degreed. Number seven, using F-E-L-P-R-O head gaskets that always cause oil leaks. Number eight, using intake spacers (15 HP loss) and or Offy intakes (75 HP Loss), costing torque and HP. Number nine, Modifying the heads for non-Buick type springs, that will put the spring in the push rod hole, distroying push rods.. Number ten, installing any distributor in without re-curving it correctly, especially the MSD units! Number eleven, not tightening the balancer bolt on the crank to 220 lbs, damaging the crank and cracking the balancer. Number twelve, listening to Chevy builders and using too small of a carburetor,. Number thirteen, mixing up 1953-55 and 56 and later lifters and push rods. Number fourteen, using gaskets on the exhaust manifold to head, causing manifold cracks, Buick did not use them. Number fifteen, mixing up water pumps with the wrong timing covers, three different gasket surface shapes.