The International Cessna^® 170 Association

Gary, unless the prop control lever is hiding behind the fresh air heat scoop it does not appear there is a crank on this engine.

John, I was looking at that picture earlier but I think, like you said, the valve may be behind the scoop. The "2H" is where the model number is normally stamped on the data plate.

Nice looking bird. Is she painted or bare metal?

It has what I would call a home grown hanger paint job. Not the best but definitely not the worst. Some of the silver paint is peeling. Something I hope to address down the road.


I don't recall seeing that lever on the left side. Here is a slightly better picture angle. I will be out there tomorrow afternoon and will verify. It's a 1952. Did they still have the C-145 in that year?



This is the right side of the case.




The plane is all original with 2065 hours. I do not think the engine was ever overhauled but it does look like someone may have topped it at some point. It's hard to believe the compressions would be that good otherwise. The cylinders also look like they may have been painted so I am not sire. Further inspection will be required.

Nipp, make sure you check the fuel valve can be selected off before you fly it.

nippaero wrote: I do not think the engine was ever overhauled. ... Further inspection will be required.

If you look closely at your data plate picture you will see that it has either been replaced or moved. There are three holes below the plate where it (or another) plate was located. Without logbooks it will be hard to know what you really have. Because the six pins/rivets holding the plate on were not symmetrical I thought it might be a homemade plate but new plates from Continental have the spacing different along the top than along the bottom as you can see from this picture. If the prop control valve is not present I think the data plate and the engine got united later in life so to speak.

That is good info. I will look more closely at it tomorrow. The plane belonged to my grandfather since 1980. Unfortunately, he had a house fire in January and lost everything including the aircraft/engine logs. The airworthiness, registration and W&B were lucky in the plane. So we are starting over so to speak with new logs. Major bummer! He had no recollection of any major engine work... I've received all the history from the FAA but there is nothing there that indicates anything.

Anyway, I am hoping my IA will be able to shed some more light on the engine soon. It will probably go down for an overhaul soon once I get it home.

Your engine data plate is for a C-145-2H engine. This there is no doubt. As Gary points out the your data plate may not be original to the case half it is attached due to other holes being evident. However those holes may just be pilot holes that someone at the factory choose not to use. Perhaps they did not match the plate.

However the fact the left case half does not have the lever hole machined in it tells me the cases are replacement cases. Or maybe the entire engine was a replacement under the data plate. This is all perfectly legal.

There was only one case. A left and right side with no part numbers listed in the IPC (they are actually P/N 6642 and 6643). However those cases where modified depending on the engine they where intended and those assemblies then identified by each part number. See this image from the IPC:



In later years we know the cases where not identical to the original because castings are different, pipe plugs used are different, the later castings where considered heavier or beefed up in some areas and most evident is they had through bolts in place of stud tie bolts in place 2 and 3. These cases where designated with pn 6643A1 as listed at the bottom of the IPC page 7. But the best evidence the cases changed is listed in AD 50-20-1 here in part:

• AD 50-20-01 CONTINENTAL: Applies to All Model C145 Engines, Serially Numbered 3000 to 5031 Inclusive, Except: Nos. 3612, 4650, 4652, 4654, 4671, 4676, 4679, 4683, 4690, 4710, 4855, 4889, 4904, 4996, 4997, 5002 Through 5021, 5023 Through 5029.
  Compliance required by June 1, 1950, and each 25-hour period of operation thereafter.
  To minimize possible engine operation difficulty due to crankcase and/or cylinder barrel failures, the following inspection procedure should be accomplished as indicated.
  (1) Visually inspect crankcase for cracks giving special attention to those areas around each cylinder base.
  This portion of the inspection need not be accomplished or new type crankcases (P/N 530836 and 530837) which are incorporated on all serially numbered engines above No. 4383, and on all engines overhauled by the manufacturer after September 1, 1949. This new type crankcase can be identified by throughbolts (extending through both halves of crankcase) located ahead of the front cylinder and adjacent to nose oil seal. The old style crankcase (P/N 6642 and 6643) requiring inspection has studs at this location extending through one crankcase half only.

If your cases are replacement cases, in today's world, this reflects sloppy paperwork (and metal work). Here is why. The engine was a 2H. By using cases not machined for the control arm they took the first steps to change this engine from a 2H to a 2. Again perfectly legal assuming they also changed out the crank. If both were done then the mechanic should have followed Continental's SB and stamped the data plate indicating the change to a 2. Of course there should also be a paperwork trail. You rarely see this back in the "old days". Of course if they only replaced the case halves and not the crank then you have a mixed engine. One not a 2 or a 2H. This is not necessarily illegal but would have to have a bases of approval today such as it being considered a minor alteration that the case halves where not machined and the lever not installed and it noted in the logs. Of course you indicate you don't have engine logs so we won't know if this apparent change documented in them.

As indicated earlier depending on the assembly, there was a different crank. There are 4 cranks for a C-145/0-300. 3 of them are listed here in the IPC image here: The first crank listed for engine A, which is for a C-125 can and was used in C-145s in '48. This is the undampened crank which is sometimes found. B and D are the C-145-2/0-300-A, C and E is for the C-145-2H/0-300-B and F and G for the 0-300-D and 0-300-E.

If you don't have crank 530860 and not 531113 then you have a C-145-2 and your data plate should be changed to reflect the model change. How could you tell what crank you have without total disassembly should you care. Remove the Hubbard plug item #5 and see if you have items 20, 21 and 22 installed as shown in the IPC. Of course someone could have removed them and you might be able to look the crank and tell if the oil port was drilled out in any way that would allow engine oil behind the piston/plug item 20. I'm not sure but if the crank is cut for the snap ring item 22 it is probably a 531113 as the ring is not called for in the other cranks.

Bruce,

Thanks for that excellent information. I was out at the airport again today and got a chance to look for that lever. Sure enough it was hiding behind the air scoop. So it would appear I have a C-145-2H engine. I also looked closer at the engine data plate. It appears to my untrained eye that the holes that are visible were never used. They almost look like they are just dimples. I need to find a piece of wire and see how deep they are.


Now, can someone educate me on what this lever actually does? It is not connected to anything.

The lever sticking out is mounted off center of a shaft. If it is free it should rotate around this shaft from front to back. It should be wired in one position. I believe that position should be to the back but I've not seen enough of these to have that memorized.

A cable is attached to the lever that you push or pull to rotate the cam. When the cam rotates it opens an internal oil passage way that engine oil under pressure flows into the center front of the crank and pushes a piston forward. It is not proportional. Full pressure or no pressure.

Don't know if Continental designed the control in anticipation of prop manufacturers making props for it or visa versa. But there are only two props I know of that require the control. The first is the rare McCauley two position prop. There is one known example being flown by a member. The other prop is the self adjusting Aeromatic propeller. The correct approved model of this prop for a 170 doesn't actually use the control to adjust but uses it to override the self adjusting feature and force the prop to the low pitch side. I know of no examples of this prop with the override in existence. Many folks don't realize there is one of this type so there could be some. There have been a few members who flew behind an Aeromatic prop but it is unclear whether they actually had the correct model installed as the do not recall.

So you have an engine with a useless feature except your one step closer than all the rest of us who dream of flying 170 with a rare unusual prop that would allow more flexible pitch than a fixed pitch prop.

Bruce, if I remember, you flew in that members '56 170 with the McCauly two position prop (Duluth wasn't it?). What was your observation of the performance? I know that member has mentioned to me on a number of occasions that he questioned the value of the prop considering the weight penalty. After his overhaul & prop tweeting I think it may have done some better. I have often "thought" I would like to have one for a marginal takeoff/climb improvement and of course a wee bit more cruise over my 115 mph. Biggest issue is there are no parts available so if something breaks one has to mfg owner produced parts.

I had a 15 minute slightly longer than around the patch flight in the plane with a two position McCauley. So one take off at low pitch, and then one observation of the level cruise flight speed verses RPM at high pitch. Pretty hard to come away from that with any solid ideas. However I saw some promise. What that means is I didn't feel the prop was worse than a fixed pitch on departure and therefor any courser pitch at cruise had to be a move in the right direction.

You are right the owner admittedly did not know much about his prop.He wasn't even sure it was setup correctly. He had never flown a fixed pitch propped 170 so he did not know whether his prop gave more performance but since he did not think it stellar he thought it not worth the trouble. If he were to insure his prop was setup correctly and he got some time in a fixed pitch I think he might have a different opinion.

I do think, know that he knows he likely has a one of a kind, he thinks it kind of neat and will keep it up as long as he can. Which is also nice as far as I'm concerned.

I think the prop shop found the prop needed some minor adjusting which may have helped.
What we need with our O-300's is an electric pitch prop

I did the same thing a year and a half ago. The biggest problem I had was the brakes would not release all the way. I took them apart and cleaned the bolts. No problems since. All the pulleys for the flight controls where kind of dry. My 56 B model sat in a hangar for 3 or 4 years before I bought it. It was in annual, not had been flown. That's what it needed more then anything. I've put over 100 hours on it since. Great airplane. Congratulations.

nippaero wrote: Now, can someone educate me on what this lever actually does? It is not connected to anything.

I just asked this same question...

http://cessna170.org/forums/viewtopic.p ... 7&p=119798

It would be neat to find a prop that used this!