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TDC

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R

RonR

Jedi Trainee
Offline
Folks,

I am helping a friend with his 12275, 12CC/Da Sprite/Midget engine.

The previous owner removed the original crankshaft pulley and replaced it with an aluminum pulley.
The aluminum pulley does not appear to have any indicator for Top Dead Center.

Short of removing the timing chain cover and aligning the marks on the timing gears, what is the best process to accurately get the No. 1 piston at TDC?

I am posting this thread in the Triumph Forum as well.

Thanks.
Ron
 
First, get the number one cylinder on the compression stroke. Remove the valve cover and the number one spark plug. Rotate the crank until the number one piston is at/near TDC. It will be on the compression stroke if both rocker arms are loose - both valves are closed.

Fashion a stop that keeps the piston from reaching top dead center. Rotate the crank until the piston hits the stop. Mark the pulley. Rotate the engine in the other direction until the piston hits the stop again. Mark the pulley. TDC is half way in between the two marks.
 
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