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How to find TDC on the 1st cylinder on L16 engine?


faldecoa80

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But the timing mark align two times, one is rigth one isn´t the TDC

 

 

That's why you need to watch the actual piston rise on the compression stroke...

 

But it also rises on the exhaust stroke. Watching it rise up doesn't distinguish compression from exhaust, nor does the timing mark. As Joel says you have to be on the compression stroke first. To do this you can stick a finger in the plug hole and the compression will blow it out or look through the valve cover cap and see if both cam lobes are pointing at 10 and 2 oclock or take the valve cover off. If you know the timing is close take the distributor cap off and the rotor will be pointing close to the #1 plug wire on it. Two things.... Now look for the single notch on the crank pulley and bring it up to the ZERO on the timing scale. Some pulleys have 4 or 5 notches and a single timing pointer. For these type set the last notch, to one furthest counter clockwise, to the pointer, the other four marks are advance.

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This is a picture of a stock 1970 L-16 timing pointer, and pulley.

TDC.jpg

This engine is about one degree before TDC.  Notice the notch on the pulley the pointer is almost centered on is larger.  That is the TDC notch.

The notch to the left side of the big notch is 5 degrees AFTER TDC.  The other notches to the right are 5, 10, 15, and 20 degrees BEFORE TDC.  The engine rotates to the side of the pulley with the four notches.

 

Like it was mentioned, this engine could be either just finishing the exhaust stroke, or the compression stroke.  You have to look at the camshaft to be sure.   If a valve on Number 1 cylinder is stuck open, or is burnt bad, you will have a harder time feeling compression with your thumb, or finger over the spark plug hole, and even on the exhaust stroke you can still feel some pressure on your thumb.

 

So to Faldecoa80, I think the best way is to remove the valve cover, or look into the oil cap hole, and make sure the front two cam lobes are at the "10:00 and "2:00" position.  Then check the position of the engine on the timing marks, and pulley.

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Alright, should have mentioned the cam lobes in the first response... Sarcasm deserved, carry on :)

 

I will add that there are quite a few different timing markers and crank pulley combos out there. Unless you're sure the set you have are accurate, I'd still pull plug one just to confirm TDC. You never know what a previous owner has done or "fixed" ;)

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