Does anyone have any information regarding the proper clocking of the prop on O-300 with an 8 bolt crank? Thanks

The guys on the 170 site will tell you to place the #1 cylinder on TDC then position the #1 prop blade pointing up and to the left (when facing the engine) at about the 10:30 clock position. This worked out for me and my C-145 on my 170.

You want that prop to stop at 10 and 4 from in front of the plane in case you need to hand prop.

MTV

I think I'd be more interested if the engine / airplane mfr says where to index the prop for proper vibration mitigation,
than where it makes it easier to prop.

The position that robw56 reference from the 170 Association comes from a Cessna service bulletin for the 170's. It does make the engine feel smoother. It may also be in the prior to 1962 100 series Cessna maintenance manual. When I get a chance in the next few days I will look it up.

Tim

hotrod180 wrote:I think I'd be more interested if the engine / airplane mfr says where to index the prop for proper vibration mitigation,
than where it makes it easier to prop.

In most cases, you'll do both. An example is the Husky, where early plane's were clocked at 10/4. Later, the company started clocking the props at 12/6. Those were a bitch to prop, and where I worked, a dead battery could leave you in a no joke survival situation.

A little research reveled that clocking the prop at 10/4 AND having the engine/prop dynamically balanced provided as good or better vibration characteristics.

In any case, look at most airplanes out there, and you'll note that most are clocked at 10/4 from the factory, not because they're easier to prop, but because that's the way they should be mounted, per the manufacturer.

But, if you ever have to prop one, 10/4 is your friend. And, if you fly the backcountry much, sooner or later you may be learning to prop your plane.

MTV

mtv wrote:.....And, if you fly the backcountry much, sooner or later you may be learning to prop your plane.

Probably a good idea to learn this BEFORE you have to do it, in the back country or wherever.
I've had to prop each of my airplanes eventually, due to a dead battery or dead starter.
Had to prop my 180 within a few weeks of buying it (old battery)--
470 thundering cubic inches, but no big deal to hand prop.
I did have someone in the front seat holding the brakes though.
Finding something to tie down to (if you don't have a parking brake) is probably the biggest hurdle to hand-propping in the field.
Don't depend too much something (often a concrete-filled bucket) tied to the tail doing much to secure the airplane.

hotrod180 wrote:

mtv wrote:.....And, if you fly the backcountry much, sooner or later you may be learning to prop your plane.

Probably a good idea to learn this BEFORE you have to do it, in the back country or wherever.
I've had to prop each of my airplanes eventually, due to a dead battery or dead starter.
Had to prop my 180 within a few weeks of buying it (old battery)--
470 thundering cubic inches, but no big deal to hand prop.
I did have someone in the front seat holding the brakes though.
Finding something to tie down to (if you don't have a parking brake) is probably the biggest hurdle to hand-propping in the field.
Don't depend too much something (often a concrete-filled bucket) tied to the tail doing much to secure the airplane.

Prime it, then mixture to idle cutoff.....it won't go anywhere. Gotta be quick to catch it, though. I've taken right side door off Cessnas, then propped from behind, with strut behind....engine catches, reach in and push mixture to rich, and set throttle.

MTV

mtv wrote:

hotrod180 wrote:

mtv wrote:.....And, if you fly the backcountry much, sooner or later you may be learning to prop your plane.

Probably a good idea to learn this BEFORE you have to do it, in the back country or wherever.
I've had to prop each of my airplanes eventually, due to a dead battery or dead starter.
Had to prop my 180 within a few weeks of buying it (old battery)--
470 thundering cubic inches, but no big deal to hand prop.
I did have someone in the front seat holding the brakes though.
Finding something to tie down to (if you don't have a parking brake) is probably the biggest hurdle to hand-propping in the field.
Don't depend too much something (often a concrete-filled bucket) tied to the tail doing much to secure the airplane.

Prime it, then mixture to idle cutoff.....it won't go anywhere. Gotta be quick to catch it, though. I've taken right side door off Cessnas, then propped from behind, with strut behind....engine catches, reach in and push mixture to rich, and set throttle.

MTV

I've hand-propped several airplanes in the past, including the 0-470 of the first 182 I owned in partnership. I really prefer to use the starter! That's why one of the many things I had added to my airplane early on was an GPU receptacle, and I carry jumper cables under the back seat. I've had to use them 3 times that I can recall for my own airplane and a couple of times for other's airplanes. As long as there's a vehicle around, and the airplane is 12 volt, it can solve the problem.

Cary

Thanks

Cary wrote:
I've hand-propped several airplanes in the past, including the 0-470 of the first 182 I owned in partnership. I really prefer to use the starter! That's why one of the many things I had added to my airplane early on was an GPU receptacle, and I carry jumper cables under the back seat. I've had to use them 3 times that I can recall for my own airplane and a couple of times for other's airplanes. As long as there's a vehicle around, and the airplane is 12 volt, it can solve the problem.

Cary

Years ago I learned how to hand prop my 'plane but have not yet had to use that talent. Floats or skis, I would prefer to stand behind the prop. I thinks that's safer. Well, on floats it's kind of essential!

I carry one of those Earth-X lithium jump packs now. Very light and easy to use if your battery is accessible (mine is under my seat).

What MTV said about starting Continentals. They like to start lean. Lycomings like to start rich and then run lean.

Mechanics got to where they were not as careful to leave the prop at 10/4. Short people cannot safely prop a plane with the prop set anywhere else. You have to carefully move the prop to near 10/4. If you are lucky you can save a little rotation for the short pull and get a start. It usually tries unsuccessfully, or worse successfully, before you are ready.

Like MTV says, "it's a bitch."

Mechanics should have to prop, just once, everything they repair requiring the prop to come off. I encountered this problem often with a rental Tri-Pacer. The master switch was under the seat and often left on. No problem; if the prop was set 10/4 the last time the cowl was removed requiring the prop to come off.