Mintor Head

[Ron Van Putte]

On Jun 14, 2005, at 8:32 PM, Ed Miller wrote:

> Anyone have a Mintor head for an OS 140 they'd like to part with ??

No.  I've using mine and you can't have it!

Seriously, I am using a Mintor 1.40 head on my OS 1.40 RX and tried 
something different.  When I got it, I asked Lance which was the 
preferred installation orientation and he responded that he installed 
it with the "extra" plug to the rear.  I told him that I thought 
installing it with the extra plug to the front might be better, for two 
reasons.  First was that the greater percentage of unburned fuel/air 
mixture was probably in the front of the cylinder and a plug there 
would do more good.  Second was that a rear installation of the plug 
would expose it to more hot, burning gases, which could degrade the 
plug.  He suggested that I try my idea and report back.

I've run the Mintor head that way for more than two months and like the 
way my engine runs.  Is it better?  Yes.  I did notice several things.  
First, the engine does go through the midrange better than with a 
standard OS head.  Second, you should add a second head shim to reduce 
the compression ratio or plug life may suffer.  Third, if you don't add 
an extra head shim, sooner or later you'll have a "center " plug 
failure (element gone).  Fourth, if the "center" plug fails, the 
"other" plug will get you through the flight, albeit at reduced top-end 
power.  Fifth, you should use Locktite when you first install the 
plugs, or the plugs will tend to back out.

Would I buy/use another Mintor 1.40 head on an OS 1.40RX?  Yes.

Ron Van Putte

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