J-5C Needs more horsepower

[thunderhead85]

I have a J-5C with the PA-18 tail and was wondering what my options might be for a bigger motor. Right now I have the 0-235 and would like a 0-320. Is there anyone on here that has a field approval for that? Also what is the likelyhood of getting one in the current field approval process. My other option would be the 0-290-D2 (135hp) which I think there is an STC for the J-5 or does the STC just cover the 0-290 (125hp) Any help??

Thanks

 

[Speedo]

Buy a PA-12!

 

[J5Ron]

Just flew a J-5A the other day with a 135...flew like a rocket, got off the ground fast...Sold my old J5 (N68931) to a guy in Wasilla...would that be you? Sure miss that plane...seemed to be a good performer...it was the best flying J 5 That I've ever flown.

Ron

 

[PA12-763]

I had a J5A with a 135HP lycoming on it (now lives in Glenallen). It was a good performer but a little light on the tail. I'm not sure if there is weight difference between an O320 and an O290D2b. That particular J5A certainly did not need any more weight on the front end of it. Just a consideration (weight) and coincidentally (reference Speedo's advice)- I did buy a PA12- and coincidentally I have done very, very few things with the 12 that I could not have done with that J5A.

 

[J5Ron]

I think your old J-5s new owner just solo'd the other day....The 135 hp J5 I flew was non electric... still a bit nose heavy...but not bad...I agree with your 12 comment...My old J5 went many places...just had to watch the weight...

 

[thunderhead85]

Did your old J-5s with the 135hp have a field approval or an STC? I found on the FAA website that there is an STC for the 290-d2 but can not get a hold of the owner, was issued in 1960. Cub club has a copy of the other STC but it is for the 0-290-d (125). I am looking at a 0-290-d2 for sale, do you think it would be hard to get this approved through the FAA? On the TCDS for 0-235-c the weight is 236 lbs and for the 0-290-d2 it is 233-236 lbs, is this right? I shouldn't gain any weight with the hp increase. Also can you run auto fuel in 0-290-d2?
Thanks for all the responses!

Yes Ron this is your old plane, flys great and can work it in 300ft places but just me and light I would like to use it loaded in 500ft places, which it can not do now. I really would like to be able to take off where I can land!!

 

[behindpropellers]

Univair has the STC for going with the D2 on the J-5A.

Tim

 

[PA12-763]

I am not sure about running auto gas, I never did. I don't have the log book for the J5A anymore and can't remember if it was a field approval or STC. I'd contact a mechanic and ask him/her.

Steve at Atlee Dodge gave me the name of a guy who was like the guru of J5s. I called this guru and he was super friendly- wish I could remember his name.

There is also a guy on this site who is rebuilding one and from his posts, seems to know about everything you'd need. Do some searches on J5s on this site and you should be able to figure out who the guy on this site is. Actually... I think he replied to your post while I was typing- pretty sure Tim (behindpropellers) is your guy.

 

[j5mike]

J5C

We just completed a J5A with the 125hp 0-290D engine. Bought that STC from Univair. The first document of the STC mentions the 0-290D only on it but the installation instructions (or supporting paperwork) mention the -d, -d2 and the 0-235. The installation instructions also had Stoddard as the originator of the STC at the top of the page. We called SToddard with some questions who was no help at all during the rebuild. Call Bill at Univair if you have any questions. If possible, I would try to get a one time STC for the 0-320. Not much if any more weight and more horsepower. The best mod we did was the Cub Crafters fuel system. Does away with the header tank which also removes some weight off the nose. Do not put a 7 gallon header tank in as that adds 42 pounds on the nose and you sure don't need it. You also will want the battery box in the same location as the PA-12 or even further aft. Wish we had installed the Super Cub trim system as the old one slips under load. Any other questions and you can PM me. Mike

 

[PilotMikeTx]

Regarding auto gas, my dad used to have a PA-20-135 (D2) with the auto fuel STC. We ran mogas unless we had to buy avgas somewhere on a trip. Never had any problems. I think the general rule is 7:1 compression you can run 80/87, 8.5:1, 90/91 and anything over 8.5 needs 100LL. That's for detonation.

 

[henryp]

J5 power

My J5 should be done in about a month. I made it as light as possible. Took out all that wasn't needed. It performed well before on 85hp but now it will be even better.