National Aeronca Association Bulletin Board

I'm still looking for a lightweight 85 or 90 hp Champ. I've found 2 that looked good, but both owners changed their minds about selling - Arrgh!

There are a few nice 65 hp Champs for sale in the $25,000 range so I'm starting to considering buying one of those and flying it a lot to wear out the C65 so I could justify upgrading to a C85 or C90 in the future.

About how much would it cost to convert a stock 65hp Champ to a C85 or C90 (CCM or DC), with the option to add a lightweight starter later (when my back is worn out). I would probably want to install a "rebuilt to factory specs" zero-time engine. I'd also prefer to keep the weight down, so no electrical.

What other "stuff" needs to be changed? i.e., firewall, engine mount, dorsal, prop, STCs, 5-gal wing tank, tail-wheel air pressure, etc?

I would PREFER to buy an airplane that someone else has labored over and invested in to get it just right, but want to make sure I don't miss another reasonable option.

Thanks,
Jimbo

We are presently building a C-85 and expect to finish within 30 days. Here are few considerations:
1. C-65 will not make a C-75, C-85 or C-90
- the C-65 crankcase is the culprit, as its cylinder outside of bore penetration into the case is a smaller diameter than the C-75 thru C-90.
2. The C-75 and C-85 crankcases are the same, as the build order for the day of original manufacure determined whether the identical crankcase casting run was made as a C-75 or C-85, or C-90, with substantial parts differences installed in the build for each designation.
3. The thought of 'future' conversion of a C-75-8, C-85-8 or a C-90-8 into a -12 (starter & generator) model involves a much thicker accessory case placing several rear-of-engine necessities further aft. The thicker -12 accesory case will require pentration recesses (cans) for both the starter & generator thru the firewall into the tank which didn't exist as originally manufactured.
4. Modifiying the engine mount frame and adding longer sheetmetal forward of the firewall does not a Champ or Chief make - as approved by the CAA in the 1940s!
5. The 7AC cowl tank 7 is 13 gallons. Generally, fuel tank capacity reduction for any 'future' insertion of the starter & generator is not a problem with the C-85. However, if you upgrade to a C-90 then you have to add fuel capacity to meet the original CAA certification requirements. A C-90-8 or -12 must have must have a 5 gal AUX tank installed as this was the only factory delivered option.
6. The dorsal fin has its own set of rules. A 7AC with either the C-75 or C-85 engine does not have to have the larger 7BCM or 7CCM dorsal fin added PROVIDED you do not want to increase gross weight from 1220 pounds to 1300 pounds. The standard dorsal 7AC flies just fine with a C-75 or C-85, but your gross weight will be restricted to the original airframe's 1220 pounds. If you want 1300 pound max gross, or a C-90 installed then you 'gots to do da tail thingy', and restamp the airframe data plate as a 7AC-CONV.
6. The Aeronca service letters spell out the requirements for engine upgrades without requiring a STC - just a log book service letter entry. Going out of bounds of the service letters will get someone else into your pocket for an STC.

Get yourself a copy of the Continental A-65,C65,C75 and C90 + others COMPARISON BOOKLET. It has a line-by-line part number difference listing with notations.

Jim,

You might also look into buying an Aeronca with a 65 or 75 hp engine on it and making the conversion without running the old engine out. They are worth more if they have a descent amount of time left on them and you can sell them on Barnstormers, Ebay or even the NAA bulletin board!

As far as changes, I believe that you and Orlan covered most if not all of them below. The Champ owners have the option of putting on 5 gallon tank in one or both wings, or going with a larger tank in one or both wings.

The Chief has a fuselage tank option that you rarely see in a Champ but I have heard that someone may have found some of these tanks if someone were interested.

Also you can use a B&C or Skytec starter in a -12 engine without any mods to the firewall. Its also lighter and most people are putting them in as a "total loss" system, that is without a generator and just charging the battery every 4-5 flights.

A question. Do you need the extra power? The extra 20 hp you get with the C-85 is really good only during the takeoff and climb phase of the flight and unless you hang a cruise prop on the plane will it be any faster. I live in Arizona and due to the density altitude need the power, but a lot of others flying the same plane with a 65 hp engine burn less fuel and fly about the same speed as I do. If you have a short strip, live at higher altitude or a warm climate, then its a valid point.

Joe A

For a great small continental engine parts interchangability catalog get a copy similar to the Ebay item currently posted # 220056215176. Or you can save some $$ and go to:

http://www.bowersflybaby.com/tech/Conti ... alogue.doc

and print your own!

Orlan

Jim; Orlan and Joe have touched on everything but I'll add my 2 pennies.

The short answer to your question "What's needed" is simple; the firewall braces. WagAero carries them for about $80-$90 or you could make your own for about $8 and 30 minutes with a welding torch.

The idea of buying a flying 7AC with a A65 and re-engining later on has a lot of merit in my opinion. It gets you into an airplane you'll enjoy, and when $$$ allows you can then upgrade the motor. There's a couple ways to get a new engine depending on your personallity. If you like a challenge and learning what makes things tick, you could scrounge up all the parts needed and O/H a C85/C90/O200 yourself (with the help of an A/P.) Or you can call up an engine shop and have them build an engine for you. With all things considered, the price will be roughly the same either way you go. I built my C85/O200 for about $9000 and I think Don's Dream Machines gets about $10500 for the same. Here's the disscusion from when I redid my motor....
http://joea.com/phpBB2/viewtopic.php?t=694

Figure if you could get a good airplane (fabric, paint, maintnence wise) for $25k then add $10k for an engine later on; you'll have an airplane that should go 20 years +/- relatively trouble free.

nkh

Get the 7AC Champ with the 65 HP Cont. Fly it and enjoy it. When the time to change the engine comes, get another 65 Cont. and continue to enjoy it. I solo in a Champ in 1960. I still own and fly an original Champ,
just for the pleasure of it.
Pablo

Amen, to what Brother Pablo said!

In addition, a prediction-that you will like the A65 so much you will keep it.

Thanks for all the replies, guys. I appreciate your taking the time to share your thoughts.

Orlan, thank you for the detailed breakdown. I see the scope of such a project is large. After years of working as a machinist, building racing motorcycles and banging my knuckles on my cars, my preference is to let someone else pour their heart, sole and money into the airplane, then buy it from them after they are done. But I realize I may not get everything I want on my wish list and might have to add or subtract something.

Joe, good point about selling the A65 while it has life and value left. To answer your "Do you need the extra power?" question, as well as to respond to Gus and Pablo, I live in Ashland, OR. The runway here is 3,600 feet long and at 2,000 ft elevation, which is all good. The problem is we are surrounded by 5-6,000 ft mountains, plus it gets 90-100 degrees in the summer. I am estimating that 65 hp would be fine if I lived in the flat, cooler terrain near Portland, but more power in the mountains would be an asset, even at the cost of another gallon per hour.

Nathan, I remember your suggestions from an earlier post about flying the airplane as-is for a while then building and installing the C85/0200. I like the ingenuity of mixing the right parts to get a little extra performance.

Because I haven't yet found the airplane I am imagining (and when I think I have the owner changes his mind about selling it), I'm starting to consider compromising. The overall sense I get from all of your collective feedback gives me some important priorities, like looking for a lightweight plane. I need to remember to be patient, be discriminating and be flexible.

Thanks,
Jimbo

Jim,

You can get by with a good airplane and a climb prop in your application.

That said, my Aeronca spent its entire life in the Rocky Mountains and NEEDED everyone of its 85 horses to do its job.

Sounds like you might want/need one as well. Mountains and DA demand power and you are right in the middle of it. Keep your eyes open and find a good airplane. Once you have that you can jiggle the engine as needed.

Joe

PS, do not forget that you can convert a A-75 to a A-75 simply by turning the RPM up a bit higher. You do need to update the pistons, carb venturi and some other things but the extra 10 hp on takeoff or climb for the same weight engine is a descent option at times. My first Aeronca had a A-75 on it and it was a nice engine.

This showed up on Barnstormers, looks fairly straight.

46 AERONCA 7AC CHAMP • $25,000 • LIGHT-SPORT AIRCRAFT FOR SALE! • 7AC Aeronca Champ, 3260 TTAF, 759 SMOH, Cont. A65, metal prop, no electric, Nov06 annual, cylinders mid 70's, polyfiber covered 1999, new wood floors 06, radio and intercom included. Flown 200 hours last 12 month. Reason selling deploying Soldier, serious buyers only, price is firm. SAFE-FUN • Contact Chris N. Hiatt - located Ponca City, OK USA • Telephone: 580-716-9153 • Posted December 5, 2006 •



nkh

I would suggest buying what you want from the beginning. I have a 65 horse Champ and after flying around at near full throttle flying from San Jose, Califronia to the Casa Grande, Arizona airshow, I vowed to put a an 85 horse engine in my plane and that's what I'm doing now..

The Champ above is a good plane and the owner is a member of the fAA Aeronca list. He is selling it ONLY as he has just gotten orders to deploy to the sandbox and does not want to let the plane sit.

Joe

I like that spinner, any idea what it came off of?

nkh

Robert E. Carr, produces new spinners and backplates that look great. For a good look-see go to Bill Pancakes Champ the Hardway article for photos. Carr's telephone in Severna Park, MD, is 410-987-4310.

I have one of his spinner & plate combo for our 7AC McDowell Air Starter. Expect to have it installed with new C-85-8 in Jan 06.

Nathan, thanks for posting the notice about that little red & white beauty.

Joe, I appreciate the inside info about it.

Carl, I'm tryin' to find what I want, but it ain't happenin'. Actually, I'm still trying to work out the details of what I want.

Thanks, guys.
Jimbo