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12.5 HP Tecumseh ?


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Wishin2BMowin
Posted
I have an 80's vintage Crapsman lawn tractor that I got for free with a blown engine. The valve seat came out of the head. I replaced the engine with a brand new Tecumseh 12.5 HP OHV from Small Engine Warehouse three seasons ago. It's running fine but skips a little at idle. I have never done anything to this engine other than oil changes and air filter cleaning. I noticed the valves are tapping more than when the engine was new. Should I adjust the valves or just let them clack away? Will this help with my rough idle or do I need to do some adjustments on the carb? It seems to be running lean to me. Just how do you adjust the valves on this engine? Will I need any gaskets, special tools or other parts to do the adjustments? I've got to keep this thing working till I get my 3212H fixed up for mowing. Thanks for any help...
Posted
To Adjust Your Valves, Remove Your Breather From The Top Half Of the Valve Cover,Than Remove The Top Half Of the Valve Cover. You May Need A Valve Cover Gasket. As Old One May Tear. Make Sure Engine Is At Top Dead Center T.D.C. The Push Rods Will Be At There Lowest Point The Rocker Arms At There Highest.Check Your Clearances Exhaust Should Be.010 Intake Should Be.005 If Not Loosen The Locknut On The Adjusting Screw And Proceed To Turn Screw Clockwise A Little At A Time To Narrow the Clearence. Check With Your Feeler Gauge, When You Have the Proper Gap, You SHould Feel A slight Drag On The Feeler Gauge Blade, Hold Your Adjusting Screw With Screw Driver, And Snug Up Locknut With Wrench. Do The Other Valve the Same Way. Remember That Before You Perform Adjustments The Engine Should Be At Top Dead Center On Compression Stroke!!!! Pull Your Spark Plug Out If Your Not Sure, And Turn Engine Over By Hand With Your Finger Over The Spark Plug Hole You Will Feel The Compression Slightly As Piston Comes Up. It May Be Easier For You With The Valve Cover Off. Than You Can See The Valves Moving. The Sequence For The Strokes Of The Engine Are Intake,Compression, Power,Exhaust. The Valve Adjustment May Help Your Idle, But Also Check To See If You Have Some Sediment Floating Around In Your Float Bowl. The Bench Adjustment For Most Tecumseh Carbs With A Float Is Bottom Screw Or Main Is Turn Screw In Clockwise Until It Lightly Bottoms Out Then Back It Out 1-1/2 To 1-3/4 Turns. The Idle Screw On The Side Of the Carb Just Above the Float Bowl Is 1-1/4 Turns After You Acheieve That, Start Unit And Run It Once It Warms Up A Bit Fine Tune The Carb Settings, Until You Acheive The Smoothest Idle And TheEngine Runs Smooth At Wide Open Throttle. Remember Clockwise Is Lean Counter Clockwise Is Rich. Hope this Helps. Good Luck Let Us Know How You Did. Jim
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