Why exhaust valve is closed after TDC?

The exhaust valve closes after a few degrees of piston reaching the TDC, i.e. when the piston starts to move down the cylinder in the suction stroke. At this point, both the inlet & exhaust valves remain open for a very short period of time; causing an ‘overlap’.

How to adjust the clearance on a Cummins diesel engine?

NOTE: The clearance is correct when some resistance is “felt” when the feeler gauge is slipped between the valve stem and the rocker lever. Locate Top Dead Center (TDC) for Cylinder Number 1 Check/adjust the valves as indicated in the illustration (I = Intake, E = Exhaust).

When to set the engine to TDC on the exhaust stroke?

NOTE When setting the engine to TDC on the compression stroke for cylinder #1, you must realize that the crankshaft rotates twice for every single rotation of the camshaft. So, if you simply set the crankshaft to TDC without looking at the position of the camshaft, you may actually be at TDC on the exhaust stroke for cylinder #1.

Where is the 1 cylinder located at TDC?

It will appear in an opening in the bottom of the clutch housing near the starter. When the groove is centered in the opening the #1 cylinder is at TDC. Personally, I don’t care for this method because if the groove is not centered in the opening, the timing can be off ±1 tooth.

Where does the crankshaft go when setting to TDC?

So, if you simply set the crankshaft to TDC without looking at the position of the camshaft, you may actually be at TDC on the exhaust stroke for cylinder #1.

How are the valves adjusted on a Cummins Engine?

I know from past work on gas engines, this was critical – maybe I am over thinking this here. Cummins manual has diagrams to say which valves are adjusted first (both valves on cylinder #1 + others), and which ones are adjusted after a 360 degree crankshaft rotation.

What is the factory manual for a Cummins Engine?

I reviewed the Cummins factory manual I have on this engine – preparing to do the first 1000 hours valve adjustment. Manual describes how to use the pin to establish TDC, but does not say anything about any need to insure TDC is at top of compression stroke or top of exhaust stroke.

Where is the dead center on a Cummins diesel?

Locate Top Dead Center (TDC) for Cylinder Number 1 by barring engine slowly while pressing on the engine timing pin. The barring gear inserts into the flywheel housing and engages the flywheel ring gear.

Why exhaust valve is closed after TDC?