Is it a good practice to cross drill a crankshaft on a 455 to increase oiling efficiency to the bearings? Or does cross drilling in some way take away the strength of the cranshaft and make it vulnerable to breaking? Any feedback would be appreciated.
Philip, In the Guide to Buick Performance Engines they talk about it and explain how to do it. They also say another way is to use full groove bearings which I have heard is less desirable. I will cross drill my crank when the time comes. Royden
I go along with what Smokey Yunick has to say in his book, "Power Secrets." His thinking being the extra hole in the crank is just another place for the wedge of oil to drop into creating a thin oil film in that area which could lead to bearing problems. He also believes in a very light, just clean em up chamfer on the crank holes. It would be interesting to see what some of the very high rpm Formula car engines do in this area. Perhaps too, what the plain bearing road racing bikes run as far as cross-drilling the crank goes could be a good indicator about it truly being required. If you can find a good machine shop that does understand performance engines and what you're tyring to accomplish without simply pushing machine work as a profit making deal, consider yourself lucky.
The industry is currently getting away from cross drilled cranks these days. They are beginning to believe that cross drilling actually hurts the oil supply to the rod bearings. I currently lean towards 3/4 grooved mains at this point. Jim Burek
