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Author Topic: OS 26FS - thin head gasket for higher compression?  (Read 1548 times)

Offline Dennis Toth

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OS 26FS - thin head gasket for higher compression?
« on: February 10, 2022, 06:27:52 PM »
Guys,
Has anyone tried using a thinner gasket in the four strokes to get a bit more compression a power? I know the FS start with a bit of a bigger ring gap the allow blowby to lub the bottom end. Some have gone to high nitro (20%) but the higher compression would do close to the same with lower nitro (lower fuel use and cost). If you have done this what thickness and material?

Best,    DennisT

Offline Dennis Adamisin

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Re: OS 26FS - thin head gasket for higher compression?
« Reply #1 on: February 11, 2022, 07:09:05 AM »
Hmmm, never heard of that, BUT remember that  if you change gaskets (thinner or thicker gasket) you will also have to reset the valve lifter clearance.
Denny Adamisin
Fort Wayne, IN

As I've grown older, I've learned that pleasing everyone is impossible, but pissing everyone off is a piece of cake!

Online Robert Zambelli

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Re: OS 26FS - thin head gasket for higher compression?
« Reply #2 on: February 17, 2022, 08:37:37 AM »
Hi, Dennis.
Not knowing the gasket thickness, I’m not sure what, if any difference this modification would do.
The 26 is a powerful and reliable engine as is.
In my opinion, it is the best of the Surpass series.
Between the 20 and 26, I have around seven or eight of these little gems and aside from a few custom venturis, they are completely stock - never had one apart.
However, it might be an interesting experiment to try.
If you have a Surpass 26, generate some data on the stock version and then install a thinner head gasket, readjust the tappet clearance and reevaluate the performance data.
For what it’s worth, I have a triple engine plane powered by three Surpass 26s. I set it up so that the outboard engine quits first, then the inboard and finally the middle.
The plane weighs just over 90 ounces and will actually fly on just the one engine.
Still though, my favorite small four-cycle engine is the Saito 30. Actually one of my favorites of all my engines.

Bob Z.


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