QuestionQUESTION: i.m in the process of replacing rings in my engine & i've honed the cylinder
just to clean it up a bit. & believe its ready. my concern is how do I know what
the ring end gap tolerances should be & if i place the new rings in the
cylinder first with the end gap facing me, will this be sufficient enough way of
measuring. My next question would be how to determine which side of the
ring and which ring or rings should face the top of the piston head. thanks
BILL.
ANSWER: Hello Bill:
Usually the Package the Rings are in will have Instructions on How the Rings are Installed Onto the Piston. However, Usually the Bevel on the Inside of the Ring Faces Towards the Top of the Piston. If the Ring has a Dot on it the Dot Faces the Top of the Piston. To Check the Ring End Gap; Place the Ring Inside the Cylinder and Use the Piston to Center the Ring in the Middle of the Cylinder. Now Use a Blade Feeler Gauge and Check the End Gap. .030in is Maximum. Usually .010in - .015in is the Maximum Ring End Gap for a Rebuilt Engine. I Suggest you have No More than .020in End Gap. 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: Hi John, i've become very frustrated with this project. If you would like the
challenge I'll start from the beginning. engine had hard time starting & finally
did not. I first noticed a missing head bolt & thought it blew a head gasket. I
changed that & also cleaned & lapped the valves. The engine backfired mainly
through the carb. After adjusting the valves 1/4" after top dead ctr on the
compression stroke at 004 intake & 006 exhaust, and there after many other
combinations to compensate for the slight grinding on the valve end to also
compensate for the lapping. nothing worked. So I did a leak down test &
discovered air coming out of the oil dipstick hole & thought The rings were
bad, so I changed the rings after honing the cylinder. I'm still getting air
leaking through the crankcase but none the less & feel The engine should
start. air gap & spark are fine, I rebuilt carb & muffler & crankcase breather is
clean & looks also fine. I hope I have not bored you to this point. do you have
any suggestions. 31h777 18hp briggs & stratton. thanks Bill
ANSWER: Hello Again Bill:
You Can Not Bore me. I Love the Challenge. From your Description, it Sounds like the Original Problem May have Been the Valve Adjustment or a Damaged Flywheel Key. Have you Checked the Flywheel Key? If the Key is Damaged it Causes the Spark Plug to Fire Slightly Out of Time and you have the Problem you Described. The Flywheel Key Does Not have to be Sheared, Just Slightly Indented will Cause the Problem you Described and Sheared will Cause No Start and Back Fire through the Carburetor. On a Small Engine I Do Not Rely on the Leak Down Test. I Do Not Even Use the Leak Down Test Anymore. You Always have Pressure in the Crankcase. That is the Purpose of the Crankcase Breather. To Limit the Amount of Pressure in the Crankcase. If the Crankcase Breather is Operating Properly, the Crankcase Pressure will Stay at the Pressure it was Designed to have. Set the Valves with the Engine AT TDC on the COMPRESSION STROKE. I Never Use the 1/4 Past TDC. I have had More Problems with Valves Using that Method. **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). Set the Cylinder you are Setting the Valves on to Top Dead Center (Both Rocker Arms will have Play in them when the Engine is at TDC) When Setting the Valve Clearance. Now Loosen the Valve Adjuster Locks and Set the Intake Valve Clearance to .004in -.006in and the Exhaust to .007in - .009in. 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.** Sometimes when an Engine has been Rebuilt, you May have to Pour a Small Amount of Oil (Approx 1oz) Into the Spark Plug Hole and then Start the Engine. Sometimes the Newly Honed Cylinder and Rings Require a Little Assist to Seat. This is the Reason for Adding the Oil to the Compression Chamber. Was the Ring End Gap Less than .030in when they were Installed? I had to Ask. Did you Place the Inside Bevel of the Top Ring so it was Facing the Top of the Piston? Do Not Worry. You Can Not Bore or Bother me by Asking too Many Questions. If you Get a Message that you have Asked too Many Follow Up Questions. Start a New Thread of Questions, Please. I Just Found Out the Site is Set Up for a Certain Number of Follow Up Questions. This is Not my Doings. I will Assist you All I can Until we Either have the Unit Running or you get Frustrated and Hit it with a Shop Maul. LOL. My Son Taught me the Saying; No Worries and I Use it Often, Now. 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: Hi John, well here we go again, I will confirm that i did have .021 end gap
when replacing the rings. and also the key way for the flywheel looked to me
to be in good shape. the only imperfection seemed to be at the bottom end
where it looked to have a notch in it but fit securely in its slot.
I have adjusted the valves at tdc as you advised & still nothing. I want to
mention two other things. when the first attempt failed to start I want to
make clear that I took a file to the stem of the valves in attempt to
compensate for the amount of metal I took from the valve heads when
grinding. I was desperate to do something at that point. Another thing when
adjusting the valves at tdc I noticed the magnet on the flywheel has just past
the area of the coil. I was wondering if this is correct position and somewhat
normal. I have been attempting to start with the fuel loading the cylinder, I
have 2 new plugs i have been alternating & I have squirted oil in the cylinder
with a pump can, but only a few squirts I feel I need to shut off the fuel to the
carb. It seems at some time it wants to start" putter, putter,putter" but only
backfires when I give it full choke. Well I guess I'll sleep on it, and again
Thanks for helping out, Bill
AnswerHi Bill:
I have a Similar Model B&S Engine that is in the Process of Being Rebuilt. I will Use your E-Mail and Try to Dublicate the Same Situtation you are having. I'll Follow Up on Monday or Tuesday of this Coming Week. Thanks.
Respectfully
John
