I have a Tecumseh ovrm 120 6 h.p. and I am trying to set the valves on it. I have looked at the Tecumseh web page and the specs. call for .004, the question I have is it BTDC or TDC?
Setting valve lash
Gene Wissink
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I have a Tecumseh ovrm 120 6 h.p. and I am trying to set the valves on it. I have looked at the Tecumseh web page and the specs. call for .004, the question I have is it BTDC or TDC?
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Well I really didn't know that it mattered if it was BTDC or TDC, I would believe it would be setting the gap when the valve is closed all the way, measured on the valve stem to rocker or tappet, which ever the case is. I would figure that there would be two different gaps, one for intake and a larger gap for the exhaust. But I am guessing.
TDC, .004 on both the intake and exhuast G W. :fing32:
Tony
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How can you tell if the valves are closed? This stuff is new to me, the last valves I adjusted was on a chevy and I did that when it was running.
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Hey Walt, I do it every year on a couple of Chevys, one is a four and one is a six
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You are right. but you have to have a starting point after replacing a valve.
1 is Intake Stroke
2 is Compression Stroke
FIRE!!
3 is POWER Stroke
4 Is Exhaust Stroke.
you have to look, the tappets will be at the lowest point, and the valves will be closed, you have to be able to see the tappets or rockers to adjust the valve lash.
The valves should be closed on any 4 cycle engine, every other rev when the piston is at it's highest point in the cylinder, that is TDC on the compression stroke, at the point that a non spark-advanced engine fires.
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BTDC= Before Top Dead Center.
If it were BTDC, youwould need an additional dimension stating HOW MUCH BEFORE.
Briggs OHV engines adjust with the piston 1/4" down ATDC. After TDC.
Note the 1/4" dimension, which is how much after.
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