Cont C90-12 Overhaul cost

WWhunter · Post by **WWhunter** » Sun Sep 07, 2008 08:19

I guess I should have posted this underengine but I figured it would get more views here and the powers that be may want to move it there anywas.

Okay here goes....I looked at a J-3 (sorry guys) that the guy is interested in trading for my 172. I WILL be keeping the Super Champ so don't dispare!

This J-3 has a C65, 1320 floats,skis, 8.00-4 tires. It was a total restoration about 4 years ago and has 53 hrs. The guy also has a C90-12 that is going with the trade. This engine is a runout and in pieces in several boxes. I really think this plane will be rather anemic on floats with the 65 and would like to put on the C90.

So, long story for a short question....What can I expect to pay to overhaul this C90? I know there are many variable as to what needs replacing etc. but trying to get a ballpark figure to see if it is worth it. Like everyone else, money is tight these days.

Any ideas on how to get the most power out of the 90? Possible flow matched cylinders? Supercharger? Nitrous? JK!!!

Thanks,
Keith

Paul Agaliotis · Post by **Paul Agaliotis** » Mon Sep 08, 2008 07:50

Keith,
The cost for overhaul is going to be a little over 5K, provided all of the parts can be made serviceable. This cost would assume that all of the labor will be done by you.
There is not much you can do to increase the performance of the engine. Aircraft engines are not performance orientated and performance modifications typically don't have much effect.
For a seaplane I would install a long flat prop to maintain max RPM. A C90 on a J3 should have enough power to drag it around.
If the airplane doesn't have aux tanks your range will be pretty short with the C90.
Paul

Post by **joea** » Mon Sep 08, 2008 08:03

Keith,

One thing that I will not assemble any engine without doing is balancing the internal components. Prolly will not give you .1 more hp but hopefully the engine will be smoother and you will feel the difference.

Joe

WWhunter · Post by **WWhunter** » Mon Sep 08, 2008 08:22

Paul and Joe, thanks. This plane has two 11 gallon wing tanks, so it has 33 gallons total which is great. The problem I have been seeing is that the -12 engine is not approved on the J-3, and it seems that 337's are getting harder to get through. As for balancing and flow matching, I worked in a speed shop many years ago and had planned on doing what I can to help the engine breath better.

Don't fret guys about me getting rid of the Champ.

After getting into the Cub the Champ feels like a luxury car!! LOL

Paul Agaliotis · Post by **Paul Agaliotis** » Mon Sep 08, 2008 08:37

Keith,
If you send the rotating assembly out for balance make sure they understand the engine is opposed and has a 180 degree crank. They should be able to see this. Most shops cater to the inline or V type engines and the bob weight required is quite different.
Paul

Jon B. · Post by **Jon B.** » Mon Sep 08, 2008 16:09

Keith:

It'll cost more than you budget; that much is certain!

I figured $4k but spent about $9k. It had only about 400 since a major when I got it. It turned out that the primary tool used on the overhaul was a pencil! The case was cracked and not repairable - $1200. The oil pump was scored and beyond repair - $800 for a new accessory case. There was two thousand I hadn't planned.

I wasted money having the cylinders overhauled but should have just bought new ones at the outset. I replaced one later, spending what it would have cost to buy two new ones. Had I bought all four, the cost would have been the same as rebuilding 4 and buying one new one. Start with new; you'll be glad you did it.

However you do it, plan on spending ten thousand bucks, send it to a quality engine shop - Bolduc, maybe - and enjoy the end product.

Jon B.

WWhunter · Post by **WWhunter** » Mon Sep 08, 2008 19:41

Thanks Jon. Thats about Ten Thousand more than I have right now! LOL This deal is still in the works so it may just be all hot air. If I get it, it'll be awhile til I can afford to swap engines.
Keith

Nathan K. Hammond · Post by **Nathan K. Hammond** » Mon Sep 08, 2008 23:33

Keith,
Here's is the break down from my Super-85. Prices should be fairly close to today's; maybe 4-5% higher. It will at least give you a ballpark figure.

http://www.joea.com/phpBB2/viewtopic.php?t=694

nkh

Holcombe · Post by **Holcombe** » Tue Oct 21, 2008 11:07

For comparison only, I had my C-90 rebuilt a year ago at Premere in Troutdale, Oregon.
First class work, and I have the clean firewall to prove it.
Engine needed new crank, cam, followers and four new cylinders. Cases and data plate remain original. Long story there.
cost 12 grand
Yes it cost a lot, but it sure felt good at 12,000 feet over the Rockies on the way into Kalispell Montana last summer.