The International Cessna 170 Association

I am the owner of a 170A model and am doing some research into engine upgrades. Originally was not planning on upgrading the motor in the 170 because it was fairly low time when I bought it, but at the most recent annual a large crack was discovered in the case so now in for quite a bill either way to repair the O-300 (in it currently) and looking at options for upgrades. So far, from reading other posts on this page it seems like a good number of owners have done upgrades with Lycoming or Continental IO-360s (and constant speed props), O-360s (mostly constant speed props), and an occasional O-320 or Franklin. Does anyone have recent data suggesting which all of these STCs can still be accomplished? I spoke with Stoots Aviation who said they have STCs for IO-360s (constant speed) and O-360s (fixed pitch), and left a voice mail with Del Air but no reply yet (Stoots said Del Air does O-360s both fixed pitch and constant speed). I received a couple quotes from Stoots, does anyone have recent data they'd be willing to share with me regarding costs of Del Air or any other STCs which might be out there? Or any other data points they feel is worth passing regarding engine modifications? The takeoff and climb performance I get with the plane now (O-300, Avcon STOL kit, climb prop) are adequate if not excessive for what I'm doing with the plane, however someday the plane may end up in a higher elevation area like Colorado and with more payload (i.e. kids) the idea of having more power sounds like a very nice idea (after flying various engine'd 172s around CO for a few years). Thanks for the help! Feel free to send me a message as well at ben.e.jones91@gmail.com.

Ben Jones

Big welcome to you Ben, thanks for contributing to the forum. Your question gets asked about every 8 months, and has been for some time. Often for a similar reason, an owner has come to a tee in the road, with a big bill should they rebuild or upgrade. The search function is your friend here on the forum. My take, if time continued would be low, repair. If you can find a low time replacement 0-300, wouldn’t that be nice. Upgrading is costly but when finished, upgrade planes are deemed more desirable hence easier to sell. That doesn’t mean you’ll recoup costs so its a route for those who intend to keep it for the long, long run.
No idea why this topic never gets old,

Welcome also, Ben!
Jim’s suggestion is a good one IMO. If engine conversions are popular.... one reason is because the cost can be reduced by selling your Firewall-forward to recoup some of the costs. You might find a good deal on one to keep an O300.

BTW, your thinking of the “increased payload” you expect in the future.... should keep in mind that an engine conversion virtually ALWAYS reduces useful load... and that will not help that situation.

I've been talking with Chris as Del-Air the past several months. He can be slow to get back to you at times, but he will get back to you. Try to call between 0800-0900 California time - that's the best chance to get him it seems. He offers several other STC that complement the engine upgrade (battery relocation, stainless firewall, long-range tanks, etc.) and a few other nice STCs for the instrument panel.

His STC is a little over $15K, but is as complete as possible. For his constant-speed conversion, he uses the O360-A1A or A1D which are very readily available on the used market in various conditions.

I'm planning on running a newer composite prop (MT or Trailblazer) and that's going to add about $15K on top of the STC and engine. Of course, you can run the stock Mooney prop and save yourself some money, but most of the hubs have a recurring AD.

I can tell you he is out of stock and awaiting components for the STC. When I spoke to him last (about 3 weeks ago), he was anticipating it being late summer - he was hopeful for late Jul, but said it would likely be Aug.

Bought a new governor lately, or for that matter other components which used to be costly? Now with consolidation in part producers, aviation companies getting bigger by acquisition and the reduction of scale in general aviation, prices for parts now are dropping jaws everywhere. Getting the kit is the easy part (sometimes).
I’m looking to replace my alternator and doing away with my Alcor (remember them) electronic regulator and separate over-voltage relay. I think the cost is about $ 1500 Canadian plus shipping. Seems expensive for what it is.

Thanks everyone for the help! Appreciate the thoughts.

- Ben

I thought that sounded like you on the radio at GWW a few weeks ago, Ben. I suppose you bought Kenneth Cox’s airplane?