Thread: Common Engine Building Mistakes

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Robot, you are the man. Thank you for creating this most sorely needed thread. And thanks Glenn for pitching in.

My first contribution will be lack of knowledge about what you're doing in the first place. I know little or nothing about the workings of a computer, so for me to sit down and try to build a mother board without reading and researching how to do it would be ludicrous. Yet, every day, I find myself lining out the basics for some newbie and trying to fix what he screwed up. Not that I mind doing it, I don't, but if the guy had just done some reading before starting off or had asked some questions before choosing parts that won't work together, he wouldn't be facing wasted money, wasted time and wasted effort.

Secondly, it must be because there is some romaticism surrounding the camshaft that causes newbies to buy the cam first, before they have any clue about anything else in the motor. As Robot said, you need to sit down and line out everything as a COMBINATION based on the intended purpose of the vehicle, the weight of the vehicle, the rear gear, the suspension systems front and rear, the transmission, the converter (if auto), the piston crown volume and combustion chamber volumes, gasket volumes, piston deck height, block deck height, compression height of the pistons, etc., etc. so that you can calculate the static compression ratio. You CANNOT intelligently choose a cam without knowing the static compression ratio of the motor. The cam should be the next to last purchase, with the converter being the last.

This one is important enough to repeat from Robot's list....
"Buying used parts without verifying what they are. Again, how many times have we seen someone post "I need to identify this cam that I bought really cheap at the swap meet." Why did he buy something that he had not already identified? Buying used parts is risky enough but buying unknown used parts is a poor use of money."
NOW HEAR THIS FELLOWS: A used flat tappet hydraulic or flat tappet solid camshaft has only one valid use....AS A DOOR STOP!!@!!! A roller cam can be re-used in the same block or in another block, but not a flat tappet cam. Once you take it out of the motor, it must either be re-installed in the same block or used as a door stop. It will not work in another block because of the variances in machining at the factory when the blocks were manufactured. Once in a while, if you're using bone stock worn out valve springs, you can get by with it if you use new lifters. But 99% of the time, you'll re-use it with stiffer springs and find yourself having to tear the motor down to clean the shrapnel out of the oil galleys so you can build it again with the proper parts. Wasted money, wasted time and wasted effort.