Converting Aeronca Chief to C-85-12

I am contemplating converting my 1946 Chief from an A-65-8 to a C-85-12 since I have to remove the A-65 for a bearing failure. My wife hates my having to hand-prop, and on chilly days, I don't like it much, either. Having an electrical system for powering radio and GPS would be great, too.

I would like to hear from anyone who has converted under the Lasher STC-- any installation issues? Any interference w/ firewall? Weight and balance issues? Where did you put the battery? Any stories I ought to hear would be most appreciated. Note that my airplane has the larger dorsal fin and modified firewall, as if it were converted at some time in the distant "logs-lost" past.

Thanks,

Hunter

I'm an Aeronca project owner, but can't help much with your question other than to point you to the National Aeronca Association forum. I'm sure someone there has experience with the engine swap. You can join for free or you can just search through the existing threads without signing up. Here's a link to the board:

http://www.joea.com/phpBB2/

As a type certificated aircraft you will need to work with an A&P/IA to handle the paper work. Such as FAA form 337. There is no reason that you can not do all the work yourself. However you will need their licenses to do the above. Do not do the work and then contact the above or your EAA technical counselor later. They need to be in the loop as the work progresses.
First. go on line to FAA.Gov and look up the TCDS (type certificate data sheet) for the 11AC. It may allow you to make the conversion with out an STC.
Second. Research all the data that makes up the Super Chief (85 HP). Many years ago I did a simeler conversion to a 7AC chanmp. and Found that the small stuff. Like the fuel line size and structural tubing changes required and matching the propeller were more important than just swapping the engine. I believe that you will find that the C85 and A65 use the same mount.
It is a simple and good conversion. Go for it and enjoy.

I'm going thru this on a '41 J4A. Depending on the available fuel head, you may have to replace the carb. See the C-85 type certificate data. The oil tank may also have to be swapped out to clear everything.

Hunter,

You don't need an STC to convert your 11AC Chief to a C-85 engine. Check the TCDS - A-761. In it, you will find:

"III - Model 11BC, 2 PCLM, ApprovedAugust 26, 1947(Model 11AC eligible forconversion to Model 11BC when accomplished in accordance with Aeronca ServiceLetter No. 17.
The nameplate must be re-stampedwith the proper model designation and the letters "CONV" added. Theairplane serial
number should not be changed.)"
To convert to a C-85-8F, it's pretty much just a log book entry. To convert to a C-85-12, it will entail some additional substantiation to show the...gentlemen...in the FAA (should it ever come under scrutiny) that the -8F and -12 are the same with only minor differences as listed in TCDS E233. The -8F and -12 are under the same Type Certificate (E233).

My '46 Chief has been converted to A-75, but still no electrical system. I can't offer any helpful tips except to say,"I like the power on climb out".
Mine has plenty of compression. It is about all the compression I want pull through when propping, especially when it doesn't start right up. Depending on your age and physical stamina, I think the C-85 will surely need the electric starter. I wish mine had it.
Have fun!!

Hunter, By way of adding to your project thinking I have two bits of info that may help.
1) You may have 'lost logbooks' but the FAA has all the 337's ever filed as well as all the pre 1958? 'annual airworthyness inspections'. Email the FAA (www.faa.gove and search aircraft records) or call the Aircraft Registration Branch at 866 762-9434. Ask the nice folks for the "Blue plate special" and for the total of $5 (it may have gone up to $10) you will get all the FAA file data on a CD or paper if you prefer killing trees. There are 3 parts, ownership, inspections and 337s. These will include all the documentation on your aircraft from original airworthyness cert through all the liens etc. That may help you determine if someone already installed a -12 engine on that airplane. Even if the mechanics of the day did the install as a 'minor alteration' (log book entry because it is approved on the TCDS) the early 'annual inspection reports' (done every year until about 1958? will show the engine installed at the time of that inspection).
2) I had a 7AC that had been converted to a C85-12 using the Lasher STC but they also changed to the later (7EC) engine mount. This moved the whole engine slightly forward. It always flew sort of nose heavy solo but we carried a 35# shot bag strapped into the back seat. You would have to do the wt and bal math for the 11 series (carefully..please) before you decide. There is also about a 13# difference in weight between a wood prop and a metal prop. The wood prop, that far forward might get you back more toward the 'comfortable end' of the CG envelope.

Hunter,

I recently completed the conversion of my 7AC Champ under the Lasher STC. I installed a C85-12F, added a Sky-Tech starter and an Odyssey battery, without a charging system. The C85-12F was modified by the O-200 conversion. I used an A&P, IA to work with me. You will need to use a C85-12F if you want the starter for several reasons: it accepts the starter on back of the engine and you don't need to modify the firewall. It is good that you have the enlarged dorsal fin and modified firewall (with additional supports) because they are called for in the Lasher STC. You can see a few pictures of my project here:
http://s900.photobucket.com/albums/ac207/RRHaldeman/

Awesome RR! Good on ya! Good information. How does it fly compared to the old -65?
Tom

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Originally Posted by Max Torque

How does it fly compared to the old -65?
Tom

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Faster, climbs like a bandit.

Great looking restoration!!

Did you have any problems getting the Odyssey battery and Marvel carb approved?

I'm nearing the end of an 11-BC Chief restoration using the Wagner STC and an O-200. Lotsa work/$$ in the o-200, and I'm now hearing some disparaging opinions about how it compares to the "super C-85." The tandem Swoards STCs would (I think) let us turn the O-200 into a C-85 by installing a C-85 cam and lifters, with the "super C-85" (O-200) crank, etc. Among the dollar drawbacks would be using a C-85 stromberg, so your use of the Marvel sounds encouraging! Of course tearing down a prefectly good O-200 that's already installed on the plane feels pretty disheartening, so I'll probably fly it first and see how I like it. Good to see you were able to sub a Marvel for the Stromberg and get the Odyssey approved, though!

I added to this thread back when you were looking at your paperwork (old lost paper trail...). You've come a long a way, nice job. Get the bird FLYING. As an old A&PIA and 'old' airplane builder I have listened to Don and others talk about the higher power from the 85 vs the O 200. The charts are real and basically, IF you are building up a C engine you want to build with the C 85 cam and associated parts. It DOES have an advantage in that it makes more useful HP in the RPM range that we run these engines. Having said that, there are drawbacks IF you already have an O 200 up and running. To use the C 85 you MUST (for power, efficency and to have a mixture control, not law) use the correct Marvel Carb (10-4240 or the very much older 10-2899) vs the Stomberg that can not have a useful mix control. trouble is they made very few of these. There is a new (store bought) way to get there. You can have G&N aviation convert your O 200 carb with the use of an STC and they get the new jet from Tempest (the MS off shoot of Tempest..) but, unless you have a fresh overhaul carb that is acceptable to G&N it is an expensive ($12-1500) proposition to re build and re jet.

Bottom line, I would leave your O 200 on, tweak your prop for what you want the airplane to do and leave well enough alone :-)). IF you were building the engine from scratch or you have money burning a hole in your pocket, yeah, the C 85 with or without the O 200 crank will give a little better performance BUT.. I flew two of us in a pre war Chief behind a tired old A65 for lots of hours and in an out of some interesting places in the hot Alabama, GA, FL summers (back when the air was denser and we were thinner..LOL). Spend time on your flying skills, use the engine you've got and go FLY!.

RR -

Hope you're still on the forum ... I'm ready to put a starter on my '46 Champ with a C-85-12. Sky-Tec is the starter, but what battery should I be looking for? I see you used an Odyssey, but I'm not up on batteries/brands so a little user insight would be welcome. What did the starter installation cost? I have a shop quote of $80/hr for a 10-15 hr job. Sounds long - doesn't look that complicated.

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Originally Posted by John P

RR -

Hope you're still on the forum ... I'm ready to put a starter on my '46 Champ with a C-85-12. Sky-Tec is the starter, but what battery should I be looking for? I see you used an Odyssey, but I'm not up on batteries/brands so a little user insight would be welcome. What did the starter installation cost? I have a shop quote of $80/hr for a 10-15 hr job. Sounds long - doesn't look that complicated.

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I've got a C-85-12 on my Fly Baby, and have had Odyssey batteries for about 16 years now. First one lasted about nine years, second was far shorter (left the Master on....) and the third one has been in place for about four years.

I'm very happy with the Odyssey. Spins the engine nice, and never seemed to run out of juice. I replaced the first one because it "seemed" to be turning slower; probably could have got a couple more years out of it. Of course, I live near Seattle, with mild weather. I get about ten years per car battery, too.

One nice advantage if the Odyssey is that you can buy them on Amazon...and if you're Prime, shipping is free! Price was $25-$40 less than the aviation suppliers were asking, too.

Of course, the Odyssey battery is not TSO'd. Might be some additional paperwork involved.

I'd love to install a Sky-Tec on my Fly Baby, but the process is pretty intense...it's not just a bolt-on replacement, which is probably why your local shop is quoting you what seems to be a large amount of time.

If you've got a pull-type starter (vs. the Bendix kind), there's a pilot shaft in the back of the engine's accessory case that the gear of the stock starter rides on. Here's a diagram:
http://www.bowersflybaby.com/tech/shaft.jpg
The fun arises because this shaft MUST BE REMOVED for the Sky-Tec installation. I'm not sure how it's originally installed, but it was apparently pressed in with lots of force. In other words, it doesn't unscrew.

So...to remove the shaft, the installer has to use a cutting wheel and cut off the shaft. Note that the base is well inside the accessory case, which means you don't want little bits of metal flying around. So the installer has to build a kind of "dam" out of clay around the location of the shaft, to (hopefully) catch all the little pieces of metal.

And, if you think about it, the job is even tougher if the engine is installed on the aircraft. The room between the accessory case and the firewall is sufficient to fit the accessories, and it's very awkward to get at that pilot shaft.

So... that ten to fifteen hours your shop quoted might be conservative (i.e., if they're experienced, it should take less time) but I can understand them being cautious.

Other than the weight savings, do you really *need* to install a new starter? Many problem can be solved with a new starter clutch...expensive, yes, but still cheaper than the starter and installation. You might try just the Odyssey first, you might be pleased at how fast the engine turns over.

Ron Wanttaja

I have a L16 (7BCM) 0200A installed with the Wagner STC. There are a few gremlins that pop up during the conversion but things are fairly straightforth (getting the aircleaner to exit the nose bowl in the correct spot takes a bit of effort for example). I used the Skytec starter with a Concord 25 amp battery mounted behind the rear seat ala 7EC and approved 337. The prop is a Cessna 150 69X50 and I show about 90 mph and climb out at around 750-800 feet per minute but depends on temperature and weight. On thing you do a need a minimum of I believe 18 gallons of fuel. I have the 13 gallon nose tank plus WA 5 gallon wing tanks on each side.

I installed a Piper ground service plug and receptacle on the instrument panel & use that for electric starting on my J4A. On the ground at my hangar, I use an Odyssey PC680 (I could use a boat battery etc) with a 10 ft long cable to the Piper GSP. The PC680 had been used in my motorcycle for 10 years yet still cranks the C-85 very well. It is kept recharged with a Battery Tender Jr.

I use electric starting if I'm giving rides, have a bad start for some reason, etc - otherwise I hand prop my J4A from the rear.

The stud that has to be removed for installation of the starter requires it to be cut off. It is clamped in place by the crankcase halves. There is no way you want to split the case on an assembled engine to remove the stud, hence the cutoff process. A Dremel tool and a couple of extra grinding disks cut that stud over in a few minutes. However I strongly recommend you remove the engine and place it upside down on a bench and use modelling clay to positively prevent grinding dust from entering the engine! Rinse the dust out with WD40 - go ahead and use a full can for this. Do NOT try to do it on the airplane! Be sure to use enough clay to form as perfect a seal as possible.

A local very prominent engine shop with an otherwise excellent reputation had a bad experience trying to remove the stud in situ. The resulting grinding dust contamination wrecked the engine, hence the demonstrated need for very careful sealing and rinsing. I also have a full flow filter installed so maybe that's part of why I got by with rinsing out the grinding contamination.

Quote:

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Originally Posted by RRHaldeman

Hunter,

I recently completed the conversion of my 7AC Champ under the Lasher STC. I installed a C85-12F, added a Sky-Tech starter and an Odyssey battery, without a charging system. The C85-12F was modified by the O-200 conversion. I used an A&P, IA to work with me. You will need to use a C85-12F if you want the starter for several reasons: it accepts the starter on back of the engine and you don't need to modify the firewall. It is good that you have the enlarged dorsal fin and modified firewall (with additional supports) because they are called for in the Lasher STC. You can see a few pictures of my project here:
http://s900.photobucket.com/albums/ac207/RRHaldeman/

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Mr Hunter has shown a -12F. The taper shaft and 'F' flanged shaft are interchangeable at overhaul and I believe either will work just fine. I have done some 65 to 85 conversions over the years. The biggest issues of firewall clearance, without going to the 'long' engine mount MAY be solvable with the new lightweight starters and alternators... With the 'long' engine mount we came very close to fwd CG unless we moved the battery to a spot inaccessably aft. One of the solutions was to use a wood prop. That took about 15# off the nose. As pointed out above you can do this as a MINOR ALTERATION (NO STC/337) if you follow the factories service letter.

AND PLEASE.. GET WITH YOUR IA BEFORE you start the conversion! B-))

Remember, if one installs an engine-driven source of electrical power, one must then install a transponder, encoder, and (soon) ADSB-out to access one heck of a lot of airspace that that is wide open to the aircraft now. If one wants an electric starter, one might want to heed the advice of others who install bigger batteries and no power production equipment. Your mileage may vary.

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Originally Posted by Mike M

Remember, if one installs an engine-driven source of electrical power, one must then install a transponder, encoder, and (soon) ADSB-out to access one heck of a lot of airspace that that is wide open to the aircraft now. If one wants an electric starter, one might want to heed the advice of others who install bigger batteries and no power production equipment. Your mileage may vary.

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Good point. The OP was talking about an Odyssey battery, and I would have no compunction about using my current Odyssey PC680 in a no-generator situation. I've had periods where my generator or regulator has gone Tango Uniform, and did quite nicely on just recharging my battery in the hangar.

I am contemplating building a no-generator Fly Baby for precisely the reason you mention, cannibalizing my current Fly Baby for the important bits. It'd be cheaper than implementing ADS-B out.

Ron Wanttaja

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Originally Posted by rwanttaja

, cannibalizing my current Fly Baby for the important bits. It'd be cheaper than implementing ADS-B out.

Ron Wanttaja

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Spinner through rudder trim tab, excepting the alternator and a few switches?


BJC

Quote:

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Originally Posted by Byron J. Covey

Quote:

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Originally Posted by Wanttaja

...cannibalizing my current Fly Baby for the important bits. It'd be cheaper than implementing ADS-B out.

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Spinner through rudder trim tab, excepting the alternator and a few switches?BJC

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Close, if you're just looking at a straight line.

Idea is to build a new fuselage with more cockpit room. 2" wider fuselage, incline the seat-back bulkhead and add gaposis to allow the seat to move back ~2-4" and recline. Extend the forward part of the fuselage to gain more leg room and compensate for the seat movement.

Should be able to completely re-use:
- Wings
- Horizontal stabilizer and elevator
- Landing gear and struts, tailwheel and spring
- Everything forward of the firewall, including the cowling and engine mount (the plans show how to incorporate the same mount on a wider fuselage). Remove the generator, block off the opening. Leave the starter.

Strip fabric for all re-used components for IRAN. Want a new paint job, anyway.

Partial re-use includes:
- Control hardware
- Turnbuckles (will upgrade some)
- Instruments, radio
- Welded metal brackets (strip and repaint)
- Electrical system components (except generator and regulator)

With the above, I figure the wood to build a new fuselage will be $1000-$1500. Covering, with a latex paint job, may be another $2000-$3000. So it's probably slightly more expensive than ADS-B out*, but on the upside I get a brand-new Fly Baby with a larger cockpit, no two-year transponder re-checks, and a Repairman Certificate that lets me do my own inspections.

Ron Wanttaja

* Everybody TALKS about low-cost ADS-B units, but no one is actually selling one yet. Those that claim to be require that the airplane already have a compatible transponder.

Ron, why not look for a 35-45 Watt solar panel and a charge controller to keep the battery up? I think the panel I have is a pound or so, and will keep my battery up with fairly constant use. Yes, it will take sunlight to keep it charged, but it will top up while in flight (unless you're night flying). If I had been able to get the T-craft I was looking at, I would have mounted it either on the dash or on the wing over the cockpit. The one I have is flat, no metal frame on it.

Derswede

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Originally Posted by Derswede

Ron, why not look for a 35-45 Watt solar panel and a charge controller to keep the battery up? I think the panel I have is a pound or so, and will keep my battery up with fairly constant use. Yes, it will take sunlight to keep it charged, but it will top up while in flight (unless you're night flying). If I had been able to get the T-craft I was looking at, I would have mounted it either on the dash or on the wing over the cockpit. The one I have is flat, no metal frame on it.

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Airplane's in a closed hangar facing North. And look to the left for my location. As you can see, I already live where the sun doesn't shine. :-)

I had a bad generator one year, and got by perfectly fine with an occasional top-off with a car charger.

Ron Wanttaja

Oops, Seattle, the place where Brits feel the most at home. Was in England for a year, the rain stopped for two days and they proclaimed a Drought in Kent.

Derswede