The International Cessna^® 170 Association

Hi Folks;

Are the cylinders for the 0-300A and 0-300B the same cylinders? What about the exchangability of other parts between the the two models? and what about exchangability to C-145?

Thanks.

All models of the C-145 and O-300 share the same cylinders. There are actually very few differences among the various models. Details can be found in the parts catalog.

Thanks. For helping witht the info on the cylinders. What about the engine case, cam and crank for the 0-300A vs 0-300B can you tell me the difference between these? I am away from my parts manual at the moment?

Others can correct me if wrong, but I believe the biggest difference between the O-300A and O-300B is that the B case has a valve for operating a hydraulic propeller. I believe the cams are the same. I'm not sure if the cranks are different, or if you just remove a plug from the A to use it in a B. Later models had a 6-bolt propeller flange vs. the A's 8-bolt.

Ah Grasshopper (Master Po like voice) you must seek the wisdom of the forums search engine to find the light

I just ran across my engine IPC (while looking for something else, of course ), and it lists crankshaft and damper assembly pn 530860 for the C-145-2 and O-300A, and pn 531113 for the C-145-2H and O-300B. No details about the differences, just that they ARE different.

I think the "B" crankshaft is machined for sealing the hydraulic connection to the 2 position prop with an o-ring.

Sorry I obviously watched too much TV as a kid! I had a "B" engine and I'm sure it had a plug in the crank prop flange. The left hand oil gallery had the prop shut off valve in it that routed oil through another oil galley to a hole in the side of the crank. Not sure the cases are the same with regard to that oil galley or whether a different bearing shells are used at that location to allow the oil transfer. A bit from memory but there's lots of info on our site on that valve for prop control. I'm not sure when the back cases changed in design but you may find different configs there, otherwise I think its mix and match.

thanks guys. i appreciate the lessons in meditation on such engines as this. I'm looking at a 300B to use for parts and so this all helps.

The IPC is the key. Many many parts, if not all that are not model specific, are interchangeable.

For example, by part number for all models 145/300

Case halves - no number but they are the same for all models left and right.

Only one cam for all engines.

Excluding the c-125 there are 3 cranks. One for the C-145/0300A, one for the C-145-2H/0300B and then one for the 0-300-C/D.

Over the years people have swapped the cranks between models. They will all work, but legally on paper is another obstacle to work around.

All the cranks no matter the model have good value if they are within tolerance. I wouldn't shy away from this engine cause you think you need an A and it is a B. Fact is you can probably use the B on any 170 with our STC for $75.

So buy it and build it or use the parts to build another. Get the paperwork for which ever route you take.

Bruce Fenstermacher wrote:Case halves - no number but they are the same for all models left and right.

Almost the same. What Miles pointed out for the B model is also true for the C-145-2H:

cessna170bdriver wrote:... the B case has a valve for operating a hydraulic propeller.

The O-300E has a governor drive pad. According to Jim Montague the pipe plug size at the forward oil galley location is 3/8" on the O-300 and 1/2" on the C-145. The IPC doesn't show this difference. He also says the O-300 is a heavier case than the C-145. The O-300 Overhaul Manual, Section 2, 1.) "Differences in Engine Models" says this about the differences between the C-145 and O-300 crankcases:

n2582d wrote:

Bruce Fenstermacher wrote:Case halves - no number but they are the same for all models left and right.

What I should have said is in the eye's of the FAA the cases are all the same, one left and one right. There are no part numbers for either.

And as Gary and Miles highlight just because there are only a single left and right case does not mean they are all the same.

How the FAA can exist without demanding part numbers today, I don't know. but I digress

Gary,
I don't believe that I've ever heard of an "O-330E" engine. Do you have any idea whay airplane it was ever used on?
I think the last model of the GO-300 engine had pad and a governor for the CS Prop. as used on the last model of the Cessna C-175.

I'd never heard of the O-300E either. According to Wikipedia the engine was in "limited production for the Beagle B.218X twin that never went into production." I thought the Windecker Eagle was the first composite aircraft but according to the Wikipedia link this Beagle was a "plastic" aircraft. Maybe the Windecker was the first certificated composite aircraft.

Gary,
Thanks for the above, It's nice that we have someone smart enough to know or find all this interesting stuff.