QuestionHi John,
My mower stopped running and I found the the top rocker arm completely disengaged from the valve. After checking the internet I found that the clearance should be .004, but screwed up because I was missing the valve cap when I measured the tolerance on the top valve. The engine started right away, but wouldn’t restart That’s when I realized the two valves were different and I was missing the cap on the top valve. After getting a cap for the top valve and adjusting the clearance, .004, engine only backfires, and I don’t know what the problem can be.
Thank you and best regards,
Dennis
AnswerHello Dennis:
>>Sometimes when a Push Tube Jumps Out as you Described, the Flywheel Key can become Damaged and Require Replacing.
>>Also, Sometimes the .004in Clearance is Not Correct for some Reason that even the Briggs Technicians cannot Explain and the Valve Clearance has to be Opened Slightly.
>>The Following is a Basic File I made for Setting the Valve Clearances. Any Input is Appreciated.
>>**I Do Not Use the Setting Called for by the OEMs. I have Found that the Following Works Best.
>>Remove the Valve Cover (on the Dead Cylinder for Twin Cylinder Engines).
>>Check the Push Tubes and make Sure they are Not Bent.
>>Set the Cylinder you are Setting the Valves on to Top Dead Center on the Compression Stroke When Setting the Valve Clearance. Now Loosen the Valve Adjuster Lock and Using a Blade Style Feeler Gauge, Set the Intake Valve Clearance to .004in -.006in and the Exhaust to .004in - .006in. Loosen and Tighten the Rocker Arm and the Feeler Gauge is Placed Between the Rocker Arm and the Valve Top where the Rocker Arm Pushes on the Valve.
>>***BE SURE TO TIGHTEN THE ADJUSTER LOCK AFTER YOU HAVE THE PROPER VALVE CLEARANCE***
>>I have had Better Performance Out of the Mowers and Less Burnt Valves Using these Settings. Be Sure the Piston is at TDC on the Compression Stroke.**
>>If you Remove the Valve Cover and then Turn the Engine by Hand, you can Watch the Intake Valve Movement. When the Intake Valve Closes, the Piston will Just Starting the Compression/Power Stroke.
>>If the Engine is Backfiring through the Exhaust, then Open the Exhaust Clearance .001in at a Time Until it Stops Backfiring.
>>If it Stops backfiring and yet the Engine Turns Fast for 1/2 to 3/4 of a Turn and then Slows or Stops, then
>>There is a Problem with the Compression Release on the Cam.
>>If the Engine is Backfiring through the Intake, then
>>Open the Valve Clearance .001in at a Time Until it Stops Backfiring.
>>If you Hit a Snag or this Does Not Correct the Problem, I Hope to be Here if You Require More
Assistance. Hope this Helps. Let me Know What Happens, Please.
>>I Hope You and Yours had a Happy Holiday Weekend and May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.
Good Luck
Respectfully
John
PS: I am Allowed to Answer 5 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Comments and Ratings are
Greatly Appreciated. Thanks.
Respectfully
John
