Engine specs
 

Do you know what is the size of OPS's 45 shaft? 6mm,8mm?
Also , do you know what size of prop sould i use for this engine??It is on a 80cm hydro!
What's the difference between drum valve and disc valve engine?
Thank you!

RE: Engine specs
 

Hi Tolias,

If your wondering the thread size it is 1/4-28 UNF, and the ground section for the flywheel cone is 7mm. I recommend using [link=http://www.aeromarinerc.com/]Aeromarine Laminates[/link] collet (coupler). It is designed with a pilot diameter to fit the front of the flywheel and helps support it to keep its balance.

Mine is a disc valve engine, with the back of the engine holding the carb that feeds directly past a spinning disc that is driven by the end of the crankpin.

A drum valve engine will have the carb feeding into a chamber before the back of the engine, and it has a hollow cylinder that the carb feeds into that is driven the same as disc. The drum valve allows a larger air path for the intake charge than the disc valve.

The black engine is a drum rotor. You can see how it extends out past the back of the engine, and the carb is pointed down into it from the top.

When you go to tighten the collet to the flywheel, I suggest removing the front housing and placing a large crescent wrench across the counterweight to hold it. It will be tighter than using the flywheel holes and nothing gets damaged.