Mercruiser 3.0 3(c) - Easier Way To Adjust Valves!!

Описание: In this video I describe how I adjust valves on any 4 stroke engine. This one happens to be a Mercruiser 3.0 4 cylinder. The concept is to adjust the valves when that cylinder is at TDC on its firing stroke. After you adjust that cylinder you rotate the engine through 180 degrees and adjust the next cylinder in the firing order. You continue rotating in 180 increments until you have gone through the entire firing order.

If the engine is a V8, you rotate through 90 degrees at each rotation and if it’s a V6 you rotate through 120 degrees.

To either side of TDC on any piston engine on the firing stroke , there is at least 90 degrees of closed valve travel. So you have a large error tolerance for positioning the engine for valve adjustment. In other words for each successive cylinder you don’t have to be right on TDC for that cylinder, you just have to be plus or minus 90 degrees from TDC on that cylinder, keeping the sum of the nominal rotation angles intact. This fact makes this method easy because it doesn’t require any precision when rotating the engine through the firing order. I’m not sure how much precision is needed using the factory method but I would be sure and get the engine dead on TDC.

In a previous video I adjusted the valves using the method from the factory service manual. I didn’t want to confuse my viewers using my method until they had a chance to understand the factory method. The factory method is in this video:

   • Mercruiser 3.0 1(h) - Cylinder Head/Valve ...  

Btw when rotating the 4 cylinder in-line engines by hand, don’t be alarmed that they get real tight to turn and then real lose. All 4 pistons are traveling through the middle of the cylinder at the same time where maximum friction occurs on all four at the same time. It’s normal on these engines.