5. No Lube For Pressed Pins
Jon Kaase, Jon Kaase Racing Engines
"An error that many guys can miss involves street engines with pressed pins. These are assembled by heating the rod when putting it together, and they are dry. When you assemble one of those engines without enough oil on the piston and pin, the minute you crank that thing up it screeches to a stop. I've seen them where you couldn't get the engine apart because you couldn't rotate it. Every one of them was locked up like they were welded together."

6. Bad Cleaning Job
Jon Kaase, Jon Kaase Racing Engines
"An easy mistake to make involves cleaning the block. There may be a plug in the engine at the end of a blind hole that will collect trash that is missed when the engine is cleaned. If you don't take all the plugs out of the engine it sure is hard to clean it. This gets worse yet if the engine is cleaned by baking and shot tumbling; if you don't have all of the plugs out you'll find so much junk in there it is unreal."

7. Upside-Down Rings
Jon Kaase, Jon Kaase Racing Engines
"Attention to rings is an area that should not be neglected. An upside-down second ring will pump oil like you wouldn't believe. We once had a set of rings that were marked wrong on the second ring, so they went in upside down, and it smoked like crazy. Having the endgap too tight is another pitfall with rings; you can go overboard on that. On the second ring you may think you need a real close endgap when really the opposite seems to be true. The engine seems to run drier (less oil consumption) when it's bigger."

"On the second ring you may think you need a real close endgap when really the opposite seems to be true."-Jon Kaase

8. Small Cam Bearing Clearance
Jon Kaase, Jon Kaase Racing Engines
"Cam clearance is an often overlooked area that can bite you. If the cam doesn't have enough bearing clearance, it will lock up on you. Sometimes it happens even when you are trying to be careful; you know the housing bores are right and everything looks right, and you put it all together. The cam (journals) might be a little on the big side and the bearings are a little on the thick side, and it only has half a thousandth of clearance and it locks up."

9. More Cam-More Power?
Jud Massingill, School of Automotive Machinists
"The biggest mistake by far is too big of a camshaft. We don't have to have the cams as big these days because the heads move so much air that you can get by with a much smaller cam. This tendency goes back since day one-people just equate a bigger cam with more power. In all the years I've been building engines, I've seen two guys come back asking for a bigger cam for 200 guys that say, I think you were right, that smaller cam would have been better."

10. Bad Math Skills
Jud Massingill, School of Automotive Machinists
"A common problem is the builder just not knowing the compression ratio. For example, a guy might buy pistons that he believes are 10:1 or 11:1 pistons, but fails to consider the combustion chamber size. A piston may have 10:1 with a 64cc chamber, but it sure won't with a 76cc chamber. We get many guys with compression too low, and just as many with compression too high, and the builder really had no idea where it was when the engine was built. You have to measure the compression ratio or get someone to do it for you if you can't."