Hubbard Plug

[longline]

(front plug) is installed in the front of the crankshaft of new engines at the factory, even if the engine is intended to have a constant speed prop installed. It is probably best to remove this plug when you install your spiffy new Hartzell. When I removed the nearly new prop on a customer's RV8 today I found that the Hubbard plug had been bouncing around in there since new. No apparent damage done, but the possibilities... The rear plug is installed correctly.

I cannot help but wonder how much trouble they had getting the prop to cycle after that first engine start. It did not cycle until they blew that plug out, which probably took some doing.

[BillL]

I learned something new today too! I did not know they were called Hubbard Plugs and googling gives a good technical description of proper installation!

Also - that plug was a bear to remove, so what kind of pressure was generated to discharge it? Wow, a wonder something was not broken. Tough bearing.