Small Engines (Lawn Mowers, etc.): Briggs and Stratton L-head slow cranking, briggs and stratton, breather vent

Question
I have a Briggs and Stratton 18.5 hp opposed twin L-head engine. M#42A707 Type 1238 01. This was given to me and has been sitting for a couple of years. The starter barely spins the motor. It will pause at the compression stroke. I connected a new battery from one of my cars directly to the starter to eliminate any electrical problems. I read that the compression release may not be working or the valves may be out of adjustment.
  I pulled the covers off to get to the valve springs and there is no clearance between the valve and tappet. I have only worked on OHV motors and don’t know how to check the L-head. How do you check the compression release and adjust the valves?

Thanks for your help and God bless.
Greg


Answer
Hello Greg:

You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM and Enter the Model (5 or 6 Digits) and Type Numbers (first 4 digits Only). Example: 42A707-1238. Then Double Click on the Model in the Results Area. Select Sectional Index. Now you can Select the Section of the Engine you Wish to View. Setting the Valve Clearance Usually will Correct the Compression Release Problem.  The Following is a Basic Instruction File for Setting the Valve Clearances on Non OHV Engines. Any Input is Appreciated. On this Model Engine I Usually Suggest Reseating the Valves if the Valve Clearance Requires Adjusting. The Following is a General Instruction File for Setting the Valve Clearance on Non OHV Engines. **Remove the Carburetor and the Crankcase Breather/Vent and the Valve (Stem) Cover so you have Access to the Valve Stems, Springs and Keepers. Set 1 Cylinder to TDC on the Compression Stroke. Using a Blade Style Feeler Gauge, Check the Clearances. The Intake should be .005in - .007in and Exhaust .008in - .010in. If the Feeler Gauge will Not Slide Between the Valve Tip and the Tappet, then you Must Reset the Clearances. **You Will Require a Small Engine Valve Spring Compressor to Remove the Springs and Keepers from the Valve Stems.** Some Engines Use a Valve Keeper that is like Automotive Keepers (2 Cone Shaped Keepers that Set in the Valve Retainer/Rotocoil Assembly)and the Other Style is a Slotted Retainer that is Moved (once the Valve Spring is Compressed) to the Larger Opening in the Retainer and the Retainer Slips Over the Valve Stem Tip for the Valve to be Removed. Remove the Heads. Set 1 Cylinder so the Piston is at TDC on the Compression Stroke And Check the Clearances Between the Valve Stem Tip and the Tappet. The Clearances are as Follows: Intake Valve Clearance is .005in - .007in and the Exhaust is .008in - .010in. You have to Lightly Grind the Valve Stem Tip and Place the Valve Back Into the Engine (you can Hold the Valve Seated by Hand) and Check the Clearance Until you Reach the Required Clearances. **++** For this Engine Model I Suggest you Reseat the Valves while you are Setting the Correct Valve Clearance. For this you will Need a Small Valve Seat Suction Tool. This can Usually be Purchased for $10.00us and has a Suction Cup that Hold the Valve Head so you can Turn the Valve Back and Forth and Dress up the Valve Seat. Valve Grinding Compound is Approximately $5.00us a Tube and a Tube Last the Shop About a Year. It Doesn't Take a Lot to Reseat 1 Engine.**++** Once the Valve Clearances are Reached and the Valve Seat is Nice and Dull; Re-Install the Valves on that Cylinder and Turn the Other Cylinder to TDC on the Compression Stroke and Set that Cylinders Valve Clearances.  Once that Cylinder is Set, then Assemble the Engine.** 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. Have a Happy Holiday Season and May the All Mighty Bless You and Yours. Be Safe and Happy. 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. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John