Briggs & Stratton 21 HP riding mower valve adjustment

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  #1  
Old 10-03-11, 02:51 PM
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Briggs & Stratton 21 HP riding mower valve adjustment

I have a Sears Cradftsman lawn tractor, 21hp with a B&S engine, model number 461707, type 0147-E1. I change oil and maintain oil levels carefully. It is 10 years old and in excellent condition. Lately it has developed a loud tapping noise when running. It could be that it has blown a connecting rod small or large bearing, or it could be a valve(s) out of clearance. I want to check the valve clearances first to rule that out as they have never been checked in the 10 years I have had it. I do not believe this is an OHV engine. How do I get at the valves to check adjustment. Is it at the top of each of the two cylinder heads? What is the recommended clearance?

I have tried looking the engine up in a variety or manuals but the various engines have unrelated names, and I do not know the name of the type of engine I have so I can go to the correct manual. They seem to have names like L Head, and Vanguard. What is the name of mine? Any other advice? Thanks.
 
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Old 10-03-11, 03:35 PM
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The 461707 is a flathead engine. The valves are not adjustable, and by nature become tighter as the engine gets older rather than looser on this engine. Loud tapping on that engine is not a good sign. Most likely the top rod is going out.
 
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Old 10-04-11, 05:04 AM
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Thanks for the feedback. By "top rod", do you mean the bearings at the piston end of the connecting rod?
 
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Old 10-04-11, 09:34 AM
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No, the rods are one over the other in the engine. The highest one is the first to go almost always, because it is higher above the oil level. The bearing surface on it wipes out at the crankshaft.
 
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Old 10-04-11, 10:40 AM
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The first thing that comes to my mind is a engine pulley with a sloppy key - which is usually integrally stamped in the pulley stack. Or a loose engine, perhaps.
 
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Old 10-04-11, 10:47 PM
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Excellent suggestion Puey, as always, and WELCOME BACK!
 
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Old 10-11-11, 09:37 AM
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Anything further, Buddy? Had a chance to check out our suggestions?
 
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