Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties Connecting rod open forked type

Connecting rod open forked type

Moderators: Curt!, Pa

Post Tue Jul 16, 2013 5:56 am

Posts: 18
Location: Switzerland

Hello! Has anyone experience with the running conditions/behaviour of 1937-38 open bottom forked rod located in the front cylinder (stock crank case 1937 with baffle plates)? Is it a good idea to change to the later enclosed type and switch position (forked rod: rear cylinder) and machine the rear baffle plate accordingly? Thanks :)

Post Tue Jul 16, 2013 11:58 am

Posts: 103
Location: Switzerland

Does anybody know why they changed the forked rod from front to rear? And what is the reason for the window in the 37 rod that is installed in the front?

Post Tue Jul 16, 2013 7:55 pm

Posts: 1642
Location: Interlaken, NY USA

The reason I heard about changing the position of the forked rod was to reduce over oiling. Moving it to the rear slot helped block more oil from reaching the cylinder walls. Remember, this is back before there were any oil control rings on either piston. Same with that bypass valve in the oil pump, to reduce "excess" oil from reaching the cylinders at low speeds.
I always assumed the windowless design was stronger.

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