View Full Version : O-320 STC for a PA-18-105

03-12-2019, 05:58 PM
Is there an STC for the Lycoming O-320 for the early model Super Cubs? Specifically the PA-18-105? I did a little searching around and haven't seen one.



03-12-2019, 06:04 PM
Contact Univair.


bob turner
03-12-2019, 06:48 PM
I thought it was all in the type cert? I'll go look.

Ok - I see it. You have to convert to a model 150 first, so better to go STC. Might ask Robbie Grove - his is stock, except for brakes and engine (150).

If you do hang an O-320, make sure you can go 160 hp.

Finally - you do know you are converting an aircraft that will do 90 mph on 6 gph to one that may do 100 mph on ten? The 160 makes that look a lot better.

03-12-2019, 07:14 PM
Thanks, I'm not looking for more speed, but more climb and someday floats. I wasn't looking at the right one on the Univar site, but now I found it.

Steve Pierce
03-12-2019, 08:27 PM
Google this and you will find everything you ever wanted to know and more.
stc O-320 site:supercub.org

03-12-2019, 09:41 PM
Thanks, I have flaps and Cleveland brakes, so it looks like I’m part way there.

03-13-2019, 04:21 AM
Roger Borer STC SA136AL being sold by his daughter Karen Braley, I think. A call to Atlee Dodge will get you her contact number.

03-13-2019, 01:29 PM
Our Super Cub (1950, K series) originally had the flaps, no electric, and single wing tank with an O-235 that I am told was rated at 108 hp on PK 1800 floats. Before I was born, my Dad and Grandfather converted it to O-320 and added 2nd wing tank. My Dad tells me that as long as it was not heavily loaded it got off the water and landed shorter in its original, very light configuration than it does with the O-320. Said it was an absolute blast to fly. The main difference is that you can carry a heavier load with the O-320 and the extra tank gives you more range.

03-15-2019, 11:05 AM
Hey Dan,
These guys have one.

03-15-2019, 11:17 AM
Thanks for all the info, everyone. I'm about ready to pull the trigger on a more or less stock Super Cub to buy and through this site I've figured out what my options for upgrades are.

04-03-2019, 07:43 PM
Thanks to a great pre-buy, I'm now the proud owner of a 1950 PA-18-105! It will be a little while before I fly it home; can't wait for some low and slow.

04-03-2019, 08:43 PM
Don't get in a hurry to hang a 0-320 on your new bird, you might find that it's too much fun the way it is! Congratulations on your new toy!

04-03-2019, 10:11 PM
CubCrafters has an STC for the early -18’s that includes 150 and 160 hp engines and includes the Borer prop approval...

04-04-2019, 06:34 AM
CubCrafters STC requires a dual groove trim system, not impossible to install on a covered early airplane but certainly not convenient. Borer STC does not.
Keep the 108 and put a Catto on it. With an 0320 your rate of climb will increase but so will your fuel consumption. Build your airplane for 90% of the flying you will do, not the 10%. I did this same thing to a 1950 airplane, nothing that cannot be undone. If you want to chat about it my number is in the member area, Jim

04-04-2019, 09:33 AM
After some research,thanks to this forum, I won't be too quick to hang a 320 on it, but I'm glad the option is readily there. I plan to fly it as it is (and learn to fly it) for awhile, make an assessment of what needs to be done and in what order. I am somewhat of a weight freak, so sticking with the O-235 is not out of the question. Can you put a Catto on a certificated Cub? I have one on my RV-3B and love it.