How do I find TCD on this 3800?

[fearnot]

EDIT: oops, I meant TDC... duh me

98 grand prix 3800 NA

Don't see any timing marks.
How do I locate TDC without putting a degree wheel on it?

Thanks.

Ian

[fearnot]

Originally Posted by GTP Dad

Remove the valve cover on number 1 cylinder and watch the valves. When both valves are closed rotate the engine until the exhaust starts to open. Once that happens back the engine off until the valve closes and you should be at TDC.

Thank you for your input.
With all due respect this can't possibly be right.

Your telling me to find the OPEN point of the exhaust vavle. The exhuast valve starts to open nearer to bottom dead center of the power stroke.

If what you meant was to find the exhuast valve CLOSE event that would put me just after TDC between exhaust and intake.... Then what I would do is rotate until the exhaust valve is open, continue to rotate until the intake valve starts to open, At this point both vavles are OPEN / OVERLAP, then continue to rotate until I find the exhaust valve CLOSE event then back off just a bit to find an approx TDC in the mid point of overlap of both valves being open.

This does not help me find TDC on Compression/Power stroke where both valve are closed for well over 90 degrees before and after TDC.

Any other thoughts that might help?

Ian

[richtazz]

Take out the #1 spark plug and hold your finger over the hole. Have an assistant roll the engine over by hand and as the piston comes up on the compressoin stroke, you will feel the compressed air pushing hard on your finger. Find a wire coat hanger or other small stiff wire and carefully put it down the cylinder until it touches the top of the piston. Continue to roll the engine over, and when the wire stops coming up, you're at TDC.