QuestionJohn,
I have a Tecumseh H60-75296H on a craftsman snowblower. The
compression was low (65 psi) but spiked when I squirted oil in the
combustion chamber. I recently honed the cylinder and replaced the rings,
piston and connecting rod. Compression is now 105 psi.
I also rebuilt the carb and replaced all the seals, blew out the passages and
replaced the idle and main needles.
At idle and full throttle with no load (auger not engaged and not throwing
snow) the engine runs like brand new. When I engage the clutch and then put
any load on it the engine starts to stall and needs 3/4 choke or several turns
of the fuel adjustment screw to make it run rich. Even after that adjustment
it will still stall out and then it is tough to restart.
Any idea what is causing this problem? It's frustrating since the engine and
carb where just rebuilt.
Thanks,
Brad
AnswerHello Brad:
>>Did you Seat/Lap the Valves when you Did the Rings?
>>Have you Checked the Point Set Gap and made Sure it was Gapped Correctly and with the Unit at TDC when Gapped?
>>The Following is the Instruction File I Made for Removing the Flywheel and Replacing the Point Set of Most Older Mower/Blower Engines. It is the Basics and if you have a Question, Please Ask. Any Input to Make this File Better is Appreciated.
>>***Disconnect the Coil Wire from the Spark Plug. Remove the Blower Housing (metal engine cover).
>>Remove the Coil.
>>Remove the Flywheel Nut or Starter Cup (Depends on the Model).
>>Now Attach a Steering Wheel Puller to the Flywheel Using the Threaded Holes in the Flywheel.
>>Tighten the Puller. Now Hit the Puller with a Hammer. Repeat this Procedure Until the Flywheel Pops Up or can be Lifted Off the Crankshaft.
>>On Some Models you Can Not Use a Puller and Must Use a Pry Bar and a Pipe Cap that is Slightly Larger than the Crankshaft. Place the Pipe Cap Over the Crankshaft to Protect it. Place the Pry Bar Under the Thick Section of the Flywheel and Pull Up Against the Flywheel. >>**BE CAREFUL DO NOT PUT A HOLE IN THE BLOCK UNDER THE FLYWHEEL** >>Now Hit the Pipe Cap that is on the Crankshaft (covered with the Pipe Cap). Repeat the Procedure Until the Flywheel can be Lifted Off the Crankshaft.
>>*** Be Sure you have the Flywheel Torqued to the Proper Torque (I require the Model and Spec/Type Numbers Off the Engine to Provide the Proper Torque) and Set the Coil Gap to .020in.. A Cardboard Side Panel from a Drink Carton will Work for Setting the Coil Clearance.
>>The Point Set is Under a Cover Under the Flywheel. The Point Gap is Set by Slowly Turning the Engine By Hand and Holding the Point Set Plunger with your Finger. When you Feel the Plunger is at the Outer Most Point of its Movement, then Stop Turning the Engine and Using a Blade Style Feeler Gauge, Set the Point Set at .015in - .020in. .
>>On Tecumseh Engines, Set the Point Set into Place and Snug the Set Screw. Turn the Engine Until the Crankshaft Lobe that Actuates the Point Set is Fully Up on the Point Set Ear. Using a Flat Screw Driver, Open and Close the Point Set Until a Blade Feeler Gauge will Slide between the Contacts. Set the Gap to .015in and Lock the Point Set Down. **Do Not Loosen or Move the Point Set/Stator Plate. This is Not Really Required and it is Easier if Performed the way I Described and Not the Way the Tecumseh Manuals Suggest.**
>>Are you Sure the Carburetor was Soaked Overnight in Carburetor Cleaner when it was Rebuilt?
>>The Following is a Basic File I Made for Cleaning Carburetors. Any Input is Appreciated. Even though the Carburetor Looks Clean, the Internal Passages May be Restricted with Varnish that Gas Causes to Build Up over Time.
>>Spray Cleaners Remove this Varnish in Layers, so Soaking is the Only Sure Way to Remove ALL this Varnish.
>>I Suggest you Make Sure the Gas is Free Flowing to the Carburetor Inlet Port (if the Model does Not have a Fuel Pump). If the Gas is Free Flowing to the Inlet Port, then
>>**Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk).
>>The Primer Bulb is Held in Place with a Locking Collar at the Base of the Primer Bulb. Use a Small Flat Screw Driver and Carefully Pry the Lock Ring Up in Small Amounts All Around the Lock Ring until the Lock Ring and Primer Bulb can be Removed from the Carburetor Body. Usually a New Primer Bulb is Required when you have to Soak the Carburetor. The Rubber is Usually Rotted to Much for the Primer to be Reused.
>>Your Primer Bulb May Differ Slightly, but Removal is Usually Almost the Same Except for the Primer Bulbs that are Bolted to the Carburetor. These are Simply Unbolted and Changed with the new Primer Bulb.
>>I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning.
>>You Only have to Remove the Bowl (if Applicable), Float Pin (if Applicable), Float (if Applicable), Needle Valve and Needle Valve Seat if Applicable. This is a Flat O-Ring Located in the Inlet Port the Float Needle Rests in. Use a Strong Wire with a Slight Bend to Remove the Old Seat. Sometimes a Small Pocket Screw Driver can be Use Also.
>>The New Seat will have a Slightly Beveled Side and a Flat Side. The Flat Side goes Towards the Carburetor Body when Inserted into the Inlet Port. Spray the Seat with Spray Lubricant to make Installation Easier. The End of a Drill Bit that is Slightly Small than the Seat can be Use as an Insertion Tool.
>>Wear Gloves or Use a Rag when Handling the Sharpened End of the Drill Bit. Remove Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed.
>>If you are Able to Remove and Disassemble the Carburetor and Keep the Gaskets Intact, then Usually these Gaskets can be Reused. Even the O-Ring Around the Bowl can be Reused if it is Not Broken. The Only Parts you May Need to Replace is the Float Needle Valve (and Seat if Applicable).
>>The Float Needle Usually is Not Replaced Unless it is Not Operating Properly (the gas flow not shutting off and the carburetor is Flooding). Do Not Remove the Main Nozzle. This is a Pressed Fit and Removal is Not Required for Cleaning. Soaking and Blowing the Carburetor Out After Soaking will Clean the Nozzle.
>>Once Disassembled, then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts.
>>Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air.
>>***(Do Not Use High Pressure Air for the Zama Carburetors, they have Check Valves for the Primer and these are Usually Blown Out of the Carburetor if Not Careful. Allow the Zama Carburetor to Set on a Drip Pan and Dry)***.
>>****All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers. There are Several Location for the Air Mixture Screws. The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body.****
>>If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is Nearest the Engine. The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body.
>>Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore). If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required. Now Setting the Air Mixture Screws:
>>****Turn the Idle Air and Main Air Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Holding the Throttle Full Open, Start the Engine. Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs. Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required. Now Set the Idle Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.****
>>If This Carburetor has a Single Air Adjustment (Except Tank Mounted 9200 and 100900 Engine Model Carburetors), Use the Section Above that Pertains to Full Throttle RPM Air Mixture Screw and then Adjust the Screw if Required to Eliminate Any Hesitation when Throttling from Idle to Full Throttle.
>>For the 9200 Model Tank Mounted Carburetor Adjust the Air Mixture Screw Full In, then Reverse 1 1/2 Turns. Set the Throttle Lever to Full Throttle and Start the Engine.
>>Now Carefully Use 1 Finger and Open the Throttle Plate and Over Rev the Engine Slightly. If the Engine Over Revs and Does Not Struggle to Over Rev, then the Carburetor is Set. If the Engine Struggles to Over Rev, then Turn the Adjustment Screw In 1/4 Turn and Repeat the Over Rev Test.
>>If you Adjust to 1/2 Turns In and the Engine Still Struggles to Over Rev, then Return the Adjustment Screw to 1 1/2 Turns Out from Snug and Turn the Screw Out 1/4 Turn. Do the Over Rev Test. Continue this Process Until you have the Engine Over Revving without Struggle.
>>By Adjusting the Carburetor on this Style Carburetor Until the Engine Over Revs without Struggle, you have Adjusted the Air Mixture to the Best Possible Setting.
>>This file was Intended to Give you the Basic Carburetor Cleaning Instructions and May Not Reflect Your Carburetor Components.
>>If you have Questions, Please Ask. The links above Provide Good Directions on Cleaning the Carburetor. Make sure you use an Compressed Air to Blow through all the Carburetor Passages to make sure they are Clear.
>>1- http://www.repairfaq.org/samnew/lmfaq/lmclctc.htm
>>2- http://www.cpdonline.com/692509.pdf .
>>Are the Valve Clearances Set Correctly?
>>The Following is a Basic Instruction File for Setting the Valve Clearances on Non OHV Engines. If you Provided me with the Correct Make and Model of the Engine then the Specifications are Included. If Not I May be Able to Provide the Specifications if you Supply me the Make and Model Numbers.
>>The Most Common Clearances are Listed for this Engine in the Following File. Thanks. Any Input is Appreciated.
>>On this Model Engine I Usually Suggest Reseating the Valves if the Valve Clearance Requires Adjusting.
>>**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 (on Twin Cylinder Engines) 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.**
>>Please, Do Not Hesitate, If you Hit a Snag, if I Missed Something 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. Comments and Ratings are Greatly Appreciated. Thanks.
Respectfully
John
