Russ2251
AZUSA:Powered by LAWN-BOY
Increase Compression Ratio/Eliminate Head Gasket-NO MILLING
Very straight forward.
Three things are needed:
1.) A large workable surface such as safety glass and must be absolutely flat. The surface I use (accurate to a few millionths inch) is from a discarded wafer prober and is not readily available unless you have connections in the analog/digital IC manufacturing industry.
2.) LOCTITE 320 grit grease grinding compound
3.) Permatex Super "300"
Apply compound to flat surface and begin lapping by applying pressure on head and move in random figure 8 and circular patterns-clockwise and counter clockwise.
Check every few minutes for a grayish color to begin to appear. After a while you will begin to understand why gaskets are used in the first place. I have yet to find any cylinder head that was not warped to some degree.
Head lapping is complete when entire surface is a uniform gray color.
Block is done the same way but is somewhat more difficult because of it's bulk/mass.
Clean up with mineral spirits, paint thinner, or kerosene.
I highly recommend that block be completely stripped of moving parts before lapping.
Thorough cleaning after lapping cannot be over stated.
If any compound is left behind, engine damage is a real possibility.
Assembly is done using Permatex Super "300".
Apply thinly to one or both surfaces and torque to maximum factory spec and done in the correct order. You'll know if you've done it correctly when a very small amount of sealant oozes out between head and block. Remember that what ever excess oozes out is also oozing into combustion chamber. Keep it to a minimum.
Clearances must be checked before final re-assembly.
Typical Briggs head gasket thickness is about .060" which is equivalent to milling off a pretty big chunk of metal.
My 1969 5hp Briggs and all four of my Lawn-Boy DuraForces had no clearance issues, but remember that no two engines are identical. Check and re-check clearances.
Addendum 4/30/10:
Would be a good idea to re-torque head bolts after a couple of cycles...that is...warm engine up to operating temperature and then let cool (couple hours) to ambient temperature, one or two times, then re-torque to max factory spec.
Link updated 2/05/15
Very straight forward.
Three things are needed:
1.) A large workable surface such as safety glass and must be absolutely flat. The surface I use (accurate to a few millionths inch) is from a discarded wafer prober and is not readily available unless you have connections in the analog/digital IC manufacturing industry.
2.) LOCTITE 320 grit grease grinding compound
3.) Permatex Super "300"
Apply compound to flat surface and begin lapping by applying pressure on head and move in random figure 8 and circular patterns-clockwise and counter clockwise.
Check every few minutes for a grayish color to begin to appear. After a while you will begin to understand why gaskets are used in the first place. I have yet to find any cylinder head that was not warped to some degree.
Head lapping is complete when entire surface is a uniform gray color.
Block is done the same way but is somewhat more difficult because of it's bulk/mass.
Clean up with mineral spirits, paint thinner, or kerosene.
I highly recommend that block be completely stripped of moving parts before lapping.
Thorough cleaning after lapping cannot be over stated.
If any compound is left behind, engine damage is a real possibility.
Assembly is done using Permatex Super "300".
Apply thinly to one or both surfaces and torque to maximum factory spec and done in the correct order. You'll know if you've done it correctly when a very small amount of sealant oozes out between head and block. Remember that what ever excess oozes out is also oozing into combustion chamber. Keep it to a minimum.
Clearances must be checked before final re-assembly.
Typical Briggs head gasket thickness is about .060" which is equivalent to milling off a pretty big chunk of metal.
My 1969 5hp Briggs and all four of my Lawn-Boy DuraForces had no clearance issues, but remember that no two engines are identical. Check and re-check clearances.
Addendum 4/30/10:
Would be a good idea to re-torque head bolts after a couple of cycles...that is...warm engine up to operating temperature and then let cool (couple hours) to ambient temperature, one or two times, then re-torque to max factory spec.
Link updated 2/05/15
Last edited:
