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Old 09-11-2007, 12:48 PM   #1
1sicklx
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Join Date: Feb 2005
Location: Lake View, AL
Posts: 2,577
"Dot to Dot" Valvetrain Tech

Pulled from Flowtech Induction.

Quote:
Originally Posted by Ed Curtis
“I installed it dot to dot.”

This is one of the most popular comments I hear after less than ideal results are seen when a camshaft installation is completed. Just the mentioning of this sends chills down my spine.

The proper installation of a camshaft and its peripheral valvetrain is one of the most important jobs an installer must do when maximizing the performance of any engine combination. Any short cuts or miscues in this regard, and the overall success of the project, and its ulimate performance, will definitely suffer.

How can something so simple be so problematic?

Let’s start with the basic premise that everyone can have a bad day at work. Who’s to say the crankshaft keyway was machined absolutely “dead on” when the machinist set it up? I mean, even a slight error of a degree or two is no big deal considering the thousands and thousands of engines out in the world. They run, don't they? Maybe it wasn’t even a bad day but something that is machined off the mean number but still within manufacturing tolerances. What's a degree or two among friends?

Now we have the next piece of the tolerance puzzle, the timing set. There are a series of variables that can occur with this component. The relationship of the keyway to the crankshaft sprocket teeth, the location of the cam dowel hole to the cam sprocket teeth and then there’s always the possibility of “both” items being off. Why worry? Well, if each facet is off in the same direction, it is a cummulative error that will change the engine's dynamics. That's why verifying the intake ceterline as it relates to top dead center is very important.

When you're installing these two pieces to the engine, who’s to say they are so perfect, there’s no reason to check them?

Nothing is further from the truth. You'll never hear a professional engine builder say this. At least not one that knows the hows and whys of valvetrain importance. This is the type of attention to detail that separates the engine assemblers from the engine builders.

No camshaft should be just installed “dot to dot” if the installer is a professional!

Now the novice or the weekend mechanic might be able to justify doing a camshaft installation in this manner just because the tools required are not something a newbie has put the investment in. It's "almost" forgivable when this is spoken. However, when I hear his “dot to dot” comment from a shop that just charged a customer a lot of money to do the install, well, it definitely crosses the line and takes them off the referral list.

Take your time and verify everything. If you don't have the time, tools or talent to do it yourself, find a professional to do it for you. It's worth the effort!
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