valve clearence adjustment (Help)

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  #1  
Old 06-02-07, 04:29 PM
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Unhappy valve clearence adjustment (Help)

Engine: 26 HP OHV B&S
Model: 446777
Type: 0244-E-1

I'm putting the above engine back together, because a engine mech, due to his own fault, is unable to complete.

This is what he was supposed to do:
Replace the crankcase gasket, and he said the governor gear was broke so it had to be replaced.

The motor came back to me in parts. I have replaced the governor gear, which was broke, and the crankcase gasket, reset the governor shaft, and all seemed fine, it started right up and ran within specs. After about 10 minutes, the motor started running rough and I noticed black smoke, and some oil dripping out of the right hand side valve cover.
After checking the bolts on the valve cover all were loose, so I removed the valve cover and the steel push rod on the bottom was just laying there, and I noticed that the allen screw was turned way out, and the lock nut was loose.
So now I have to reset the valves. I have the B&S repair manual, but it doesn't indicate which valve is the #1 valve compression or the #2 valve intake.
Could someone help me out here, which, is which and how do I determine where TDC is.
If I don't get this tractor going soon, I'm going to have to get a hay baler.

Thanks again all
 
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Old 06-02-07, 05:18 PM
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actually you have an intake valve and an exhaust valve. The intake valve is usually located nearest the intake (where the carberator mounts) and the exhaust is often closer to the exhaust pipe.

The other way t determine which is which is simple. With the pushrods in place (be sure not to over tighten them, you don't want to put a valve throught the piston (if OHV) or into the head (if not OHV). turn the engine by hand and watch the valves. There will be a sequence you can catch on to quickly.

after a period of no valve movement as you rotate the engine, the fisrt valve to open will be the exhaust valve. then as that valve nears the end of it open period, the other valve (the intake valve) will begin to be actuated. Then after the intake valve closes, there will be a period of rotation with no valve movement followed by the exhaust valve actuating again.

have the spark plug(s) removed when you do this or you will fight the compression of the engine.

If you get a point of resistance, STOP. it is possible you have one of the valves overtightened and it is hitting something.

now to find TDC. I am not familiar with your engine. I would suppose there are some timing marks on the flywheel but not sure. If there are, there may be simply a mark or several with TDC noted. Realize that TDC will come around twice. Once with the intake valve open and once with it closed.(actually both valves may be open at this point) You want to set the valves when it reaches TDC with both valves closed.

If there is not indication as to TDC, you can do it the old fashioned method with a stick (don't laugh or I won;t finish telling you how)

as you, or somebody else (preferable)rotates the engine, insert a small stick into the cylinder through the spark plug hole. You should be able to touch the piston with the stick. as you rotate the engine, allow the stick to be pushed up and push it down to follow the piston. When it reaches TDC, it will be at the top (of course) and stop moving for a moment as the engine is continued to be rotated.

When you find this point, you can rock the engine back and forth to find the middle point of that null piston moment. You have now set the engine at TDC.

there are some guys that are much more familiar with small engines than I am and may be able to give you an easier method of reaching your goal but the forum seems to be a bit slow tonight and I think I can hear your grass growing from here.
 
  #3  
Old 06-02-07, 05:37 PM
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Good explanation by nap. By the way, normal engine rotation is with the flywheel moving in a clockwise movement. Furthermore, you should adjust the valves with the piston 1/4" past TDC (on the downstroke after TDC) on the power stroke so that any MCR (mechanical compression release) mechanism does not affect the adjustments of your valves. For the probe to insert into the spark plug hole, I recommend using a knitting needle long enough to make the full stroke of the piston.
 
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Old 06-02-07, 05:38 PM
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Red face

Nap:

Thank you for your quick response, and I didn't laugh, I'm going to give it a try right now. thanks again
 
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