TDC Question
Stage I
Joined: Mar 2026
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From: PA
TDC Question
I've just noticed the same thing you're talking about. It's been my assumption, and I think correctly, that the timing marks lined up at TDCC. Maybe not so anymore. Although stated in Feuling instructions to line up the marks at rear TDCC, if the marks are lined up properly, the piston is PAST TDCC. A recent H-D service manual does not say anything about TDCC. It says cam keyway at the top, crank flat at the top, install the gears. My best guess is the marks are for timing the cams, and that's it. They do not have a relation to TDCC anymore. And I've never seen this until M8's, and I think I would have noticed this before.
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Joined: Dec 2005
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From: poway
I've just noticed the same thing you're talking about. It's been my assumption, and I think correctly, that the timing marks lined up at TDCC. Maybe not so anymore. Although stated in Feuling instructions to line up the marks at rear TDCC, if the marks are lined up properly, the piston is PAST TDCC. A recent H-D service manual does not say anything about TDCC. It says cam keyway at the top, crank flat at the top, install the gears. My best guess is the marks are for timing the cams, and that's it. They do not have a relation to TDCC anymore. And I've never seen this until M8's, and I think I would have noticed this before.
The flat lines up with the crank pin.
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