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Jack E/NJ · 12-26-2011, 10:22 AM

Paul>>>So my question is why don't the two marks align with each other?>>>

In theory, both the combustion & exhaust stroke TDC pulley marks should align. In practice, due to 'play' as you suggest and the difficulty in discerning vertical piston movement near TDC, the midpoint between the two marks is 'assumed' to be the true TDC.

Jack E/NJ

12-26-2011, 10:22 AM	#2
Jack E/NJ Senior Member Join Date: May 2010 Posts: 2,272	Re: layman question about TDC Paul>>>So my question is why don't the two marks align with each other?>>> In theory, both the combustion & exhaust stroke TDC pulley marks should align. In practice, due to 'play' as you suggest and the difficulty in discerning vertical piston movement near TDC, the midpoint between the two marks is 'assumed' to be the true TDC. Jack E/NJ