Herkimer OK Twin Engine Run

Restoration and running of a 1940 Herkimer OK Twin 1.2 cubic inch, spark ignition, two stroke model engine. Serial #260.

[@daveschroeder1832]

At last...A running Twin....specs added to the Vid...Great Work!

[@thehydroblade]

I really need a set of blueprints/drawings for this engine to scale up for my vintage air project.

[@tomfey6020]

I am not aware of the existence or location of drawings for the Herkimer Twin. But depending on the size of your project aircraft, a WWII target drone engine might be a possibility: kzbin.info/www/bejne/pKG7XoONiKucm7M

[@MarkRobinson555]

Lovely engine, great to see it running so well, thanks for sharing

[@tomfey6020]

Thanks for the comment.

[@shootingsolution0123]

nice a sound

[@lightninrodpbn]

THANKS FOR THE DEMO .... FOR SAFETY THO IF I WAS RUNNING THE ENGINE I WOULD STICK A PIECE OF K&S ALUMINUM TUBING ON THE SPARK LEVER AS AN EXTENSION AND MAYBE SOME ELECTRICAL TAPE TO COMPLETLY COVER THE SPARK PLUGS SO YOU COULDN'T ACCIDENTALLY GET A SHOCK FROM A PLUG AND YOUR HAND GO INTO THE PROP WHEN THAT ENGINE WAS MADE SAFETY WAS VERY PRIMATIVE .... SOME CARS DIDN'T EVEN HAVE SAFETY GLASS AND NO CARS HAD SEAT BELTS OR HAZARD BLIKER LIGHTS OR EVEN TURN SIGNAL LIGHTS .... THE GOOD OLD DAYS .... LOL .... FOR STATIC DISPLAY YOU COULD OBVIOUSLY TAKE THAT SAFETY STUFF OFF .... I USED TO BE A SCHOOL SHOP TEACHER AND ESPECALLY WITH KIDS AND MACHINE TOOLS SAFETY WAS #1 .... FORTUNATELY WE NEVER HADE A SERIOUS ACCIDENT EVEN WHEN SOMEBODY DIDN'T FOLLOW THE SAFETY RULES .... ...............................................................................................................

[@tomfey6020]

Thank you for your comments. They are well considered.

[@tonywright8294]

Alternatively just stay in bed waiting to die !

[@mikesmith7249]

Really great work Tom, need this added to AEHS

[@tomfey6020]

Thanks, Mike. Yep, next eNewsletter.

[@guycummins8837]

I have one of those. It was my dad's. I've never seen it run.

[@tomfey6020]

Lucky you! They are really cool engines. Not the most powerful, perhaps not the best engineered or built, but the cool factor is very high.

[@gwheyduke]

Nice runner!

[@fvanderhorst8425]

Succes at last; you really put a lot of effort in. Great!

[@tomfey6020]

Thanks, Fred. It pays to have friends who know how to find stuff. Tom

[@robfey9616]

Classic!!

[@caesarillion]

Thank you. You are now officially a folk hero. Could you repost with idle and sustained high rpm? It is hard to tell the state of the motor in the final section. I am mocking up a Syncro Ace based inline twin so this is particularly interesting to me. Thanks, Thailand Paul

[@AEHSvideo]

Thanks for your comments. My goal was to start and run the engine for a few minutes with limited stress, then retire it. I spent no time tweaking if for peak performance and run time was total of perhaps 5 minutes. After successfully running the engine, the original timer assembly, original cylinder hold-down screws, and original rear case were reinstalled on the engine for eternal display. The engine retains the late-model crankshaft used for running. As suggested by the tachometer maker, I put a piece of reflective tape on backside of one blade of the propeller. The tach read +/- 4,000 rpm at idle = ignition timing at TDC and 7,687 rpm was the maximum rpm detected when timing was fully advanced to 30 degrees BTDC. I did not lean the engine to maximum rpm. It has been pointed out by one viewer that the true rpm's are likely half those stated above as the tach may have been detecting both propeller blades. I have been unable to find reported maximum rpm is for the Herkimer 1.2 as back in the 40's and 50's, this would be difficult to measure. I need to tach the propeller, or a black disc with one piece of reflective tape, when attached to an electric motor of defined rpm to see what the tach reads. Hope this helps. Stay tuned.

[@tomfey6020]

To address the detected RPM vs True RPM, I mounted the 16 x8 prop used on the Herkimer Twin run onto a constant-speed AC motor. If no reflective tape is used, the detected RPM is in fact double the True RPM. However, with reflective tape mounted on one blade of the two-blade prop, which is how the Herkimer Twin run was performed, the tach reads the True RPM. So the idle data shown in the video (+/- 4,000 RPM) and high speed data (7,687 RPM) is legit.