O & R timer screws

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O & R timer screws

Postby jerry1927 » Fri Oct 26, 2012 1:24 pm

I believe the early (pre WWII,) O&R engines used 3-48 screws for securing the arm and retaining the timer on the engine. When 4-40 screws were adopted (because the threads in the aluminum arms were too easy to strip,) the larger screw heads caused them to tilt because their larger size contacted the timer housing.
I have a few early engines that were refitted with the 4-40s and considered them to be wrong. So I compressed the #4 holes and reformed the threads with a fluteless (thread forming,) tap. They are now legitimate but remain fragile. I don't run them.
Have I reduced their appeal to collectors?
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