Small Engines (Lawn Mowers, etc.): tecumseh back firing and missing, valve spring compressor, valve grinding machine

Question
QUESTION: I have a 1970s ariens sno-thro, it has tecumseh model H50-65325J serial 2227D and when the engine gets hot it backfires and misses when I start to blow snow, then when I stop it smooths out. The longer I run it, the worse it gets. When it first starts doing this, it only does it for a few seconds but about 10 mins later it will do this for 3-5 mins. What is making the engine do this?

Thanks

ANSWER: Hello Geof:

From your Description, it Sounds like the Valve Clearance Needs to be Reset. If the Valves have Never been Reset on this Engine, then it is the Most Likely Cause for this Problem. As the Engine Gets Hotter, the Metal Expands and the Valve Clearance Becomes Closer than Specified. When this Happens, you May get Back Firing, Rough Running, Rough Idling and Posssibly some Power Loss. If you Decide to Attempt this Repair, Let me Know and I can Provide Detailed Instructions. You will Require a Small Engine Valve Spring Compressor to Perform this Repair. You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.outdoordistributors.com/ and Select the T. Then Select Tecumseh. Then Select Don't have Part Numbers. Then Enter the Model Numbers (H50-65325J). Then Select your Model and Download the File for Online Viewing. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 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. Thanks.

Respectfully

John

---------- FOLLOW-UP ----------

QUESTION: if I do reset the valve clearance, would I be able to use a automotive valve grinding machine to do this?

thanks

Answer
Hello Again Geoff:

To Set the Proper Clearance of the Valves on this Mower you have to Lightly Grind the Valve Stem Tip and Check the Clearance Between the Valve Stem Tip and the Tappet. You Grind a Small Amount and Then Install the Valve Back Into the Block, Hold the Valve Seated by Hand and Check the Clearance. Do this Until the Clearance is .004in - .006in Intake and .008in - .009in Exhaust. An Automotive Valve Grinder is Mainly Used for the Valve Seats and Faces. If the Valve Requires Refacing, then the Valve Grinder can be Used. If the Valve Face is Good, then Simply Grinding the Stem is All that is Required. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 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. Thanks.

Respectfully

John