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Old 04-03-2010, 08:35 PM
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Default 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
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Last edited by Russ2251; 07-26-2013 at 07:18 AM. Reason: Links updated
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Old 04-03-2010, 08:44 PM
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Awesome Thread! Do you think if i milled the head and then used Super 300 it would be too much compression?
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Old 04-03-2010, 08:45 PM
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You have completely missed the point.
Milling requires a gasket.
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Old 04-03-2010, 09:11 PM
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Okay thanks, I know the whole point was to bump the compression. Great Thread!
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Old 04-04-2010, 07:30 AM
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Awsome thanks russ!
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Old 04-04-2010, 07:40 AM
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Quote:
Awsome...
Yes it is, Thanx.
I cannot, however, take credit for this modification. It's an old trick that goes back decades.
Don't expect any speed records, but it will give you a little extra "punch" and is noticeable.
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Old 04-04-2010, 07:48 AM
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Quote:
Originally Posted by Russ2251 View Post
Yes it is, Thanx.
I cannot, however, take credit for this modification. It's an old trick that goes back decades.
Don't expect any speed records, but it will give you a little extra "punch" and is noticeable.
well im just doing it for the use of no head gasket.. i dont like spending 5 bucks and 20 bucks in gas goin to the nearest lawn mower shop then have to wait a day before they get a gasket in for me.
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Old 04-04-2010, 12:01 PM
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I always reuse the gasket if its in good enough condition. I will be glad to try this method out.
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Old 04-05-2010, 04:23 PM
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Thanks Russ, for the useful info, and Tyler for stickying it!
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Old 04-30-2010, 11:31 AM
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wait quick question i get what this is about but i really dont think that the head will mate with the head as true as stated w/ out losing some compression?
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Old 04-30-2010, 11:49 AM
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Quote:
i really dont think that the head will mate with the head...
???
Then I'm in a lot of trouble about a dozen times over.

I have had no problems...please explain question.
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Old 04-30-2010, 12:23 PM
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im saying i know you can use an engine w/out a gasket but ive only hard of it being done by being machined never heard of this method and i have my doubts about it.
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Old 04-30-2010, 01:29 PM
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Quote:
Originally Posted by Rotore View Post
im saying i know you can use an engine w/out a gasket but ive only hard of it being done by being machined never heard of this method and i have my doubts about it.
This method is just as good if not better than machining, you will most likely get a much smoother finish with this method.
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Old 04-30-2010, 01:47 PM
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hmmmmmmmm ima give it a tray
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Old 04-30-2010, 03:44 PM
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Quote:
ive only hard of it being done by being machined never heard of this method and i have my doubts about it.
You would be hard pressed to get a better surface by any other means than lapping. Even the best milling tables have to be lapped to keep them in tolerance.
As perfect as valves and seats may be machined...they still must be lapped for a proper seal.
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Old 05-01-2010, 07:04 AM
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yup i got whatyour saying russ thats pretty cool ima have to try that on my kohler
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Old 05-01-2010, 01:07 PM
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yea my local mower shop "cuts" the valve and seat, but i lap it anyways and always get slightly higher compression
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Old 05-01-2010, 01:19 PM
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Quote:
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yea my local mower shop "cuts" the valve and seat, but i lap it anyways and always get slightly higher compression
your always suposed to lap after they are cut.
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Old 05-01-2010, 02:27 PM
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Valves are lapped at factory.
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Old 05-01-2010, 02:57 PM
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Quote:
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Valves are lapped at factory.
but should be done after a rebuild or if you cut the valve seats.
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