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C-90-16 in PA-11

Steve53

Registered User
Indiana
Anyone have or know of someone that has a 337 to install C-90-16 in a PA-11. TCDS says C-90-16 is the same as C-90-12 except that -16 case has provision for vacuum pump. The C-90-12 is the same as the C-90-8 which is listed as an approved engine for the PA-11. Cub Doctor says you would just need to attach a block off plate where vacuum pump would go. Trying to make this a legal install without going through the hassle of trying to get it approved by those without any common sense.
 
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I’m by no means an expert, but I thought a-12 has provision for starter and generator and the -8 does not. The -8 only is the only C90 on the TC. If Clyde Smith says you can do it, I’d would defer to him certainly. What did he say about paperwork.
 
A field approval ought to be trivial unless it involves changing the engine mount. Do it that way, and save yourself lots of grief.

It took me ten minutes to get a dash 12 approval for a J3.
 
cub club??=
PA11
337 for 0200 in place of C85-12 (0220 100 hp derated to 90hp)…….. $5.00

337 for 0200 in place of C90-8………………………………………. $5.00
 
I’m by no means an expert, but I thought a-12 has provision for starter and generator and the -8 does not. The -8 only is the only C90 on the TC. If Clyde Smith says you can do it, I’d would defer to him certainly. What did he say about paperwork.
You are correct about the C-90-12 and the -8. You are also correct that the C-90-8 is the only one approved for the PA-11 as listed on the J-3/PA-11 TCDS. Clyde and I didn’t talk about whether it could be approved. We only talked about whether there would be installation issues with the -16 which he didn’t think there would be any.
 
Unless the 337 is pre-1955, a copy will not help much. The basic engines are identical. Point that out, and point out that a C-85-12 is ok, even with a C-90 crank etc., and they almost have to sign it. Start early; it takes me an average of eight months to get anything done, and I send a polite e-mail once a month or so.

They are working from home mostly, so you kinda have to be persistent. But this is trivial. Unless the motor mount is different.
 
You might consider initially blocking off the accessories like starter, generator, and vacuum pump if the FAA is concerned. Then the C-90-8F and C-90-16F would be quite similar except for the magnetos They rotate opposite directions. The standard alternator may not even fit with the Piper PA-11 exhaust (?). A 13A B&C may. The available carburetors for each may differ (Stromberg vs Marvel; see TCDS A-691 for Piper's -8F's callout) for example. I had a M/S spec'd for a C-90 on my PA-11-90 after a Stromberg, so it's done.

Later: Ask about adding accessory(s) previously approved via TCDS E-252 for the engine. However, adding an electrical system to motivate a starter and resupply a battery can be problematic. DER's deal with that.

Gary
 
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I have the 12 with starter and gen block off plates...works great and FAA definitely can't argue about the need for Transponders and ADSB and all that...I have the Marvel MA-3 carb and wouldn't go back to the Stromberg, if you have the option. Great little engine.

S.
 
You might consider initially blocking off the accessories like starter, generator, and vacuum pump if the FAA is concerned. Then the C-90-8F and C-90-16F would be quite similar except for the magnetos They rotate opposite directions. The standard alternator may not even fit with the Piper PA-11 exhaust (?). A 13A B&C may. The available carburetors for each may differ (Stromberg vs Marvel; see TCDS A-691 for Piper's -8F's callout) for example. I had a M/S spec'd for a C-90 on my PA-11-90 after a Stromberg, so it's done.

Later: Ask about adding accessory(s) previously approved via TCDS E-252 for the engine. However, adding an electrical system to motivate a starter and resupply a battery can be problematic. DER's deal with that.

Gary
Thanks for the info. I don’t want an electrical system so that will all be blocked off. Need to keep it light as possible.
 
One of the differences between a -8 and any of the -12 thru 0200 is that they put the engine about 5/8" farther forward changing the CG. Also hurts the performance

Glenn
 
One of the differences between a -8 and any of the -12 thru 0200 is that they put the engine about 5/8" farther forward changing the CG. Also hurts the performance

Glenn
Well that’s interesting. How did you come across that info because if it moves that much forward I’m not sure it would allow it to fit in the nose bowl. I’m going off what the TCDS says which is, the -16 is similar to the -12 but has provision for a vacuum pump and that the -12 is IDENTICAL to the -8 except that it has provisions for accessories.
 
If you zoom in on my cowl you can see how the plug blisters were moved forward when the original 90-8 engine was replaced by a 0200
Screenshot_20250126-090404.webp
 
If you zoom in on my cowl you can see how the plug blisters were moved forward when the original 90-8 engine was replaced by a 0200
View attachment 110240
I’m still confused because Univair has engine mount bushings that fit all A and C series Continental engines. They also sell a different bushing which I believe is the Lord mount for the C-90-14 and O-200 engines. The C-90 TCDS lists the -14 as using the Lord mount but it’s the only C-90 model that does.
 
I’m still confused because Univair has engine mount bushings that fit all A and C series Continental engines. They also sell a different bushing which I believe is the Lord mount for the C-90-14 and O-200 engines. The C-90 TCDS lists the -14 as using the Lord mount but it’s the only C-90 model that does.
Maybe -16 is different?
 
i have a c90-8 case on the bench right now, bare, when i stick a tapemeasure through it front to back its 16 7/8 inches, this is bare, no accessory case on it. and thats also where the back of the cone mount is from the front. and the above mount also looks like its flush with the back of the case.
 
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i have a c90-8 case on the bench right now, bare, when i stick a tapemeasure through it front to back its 16 7/8 inches, this is bare, no accessory case on it. and thats also where the back of the cone mount is from the front. and the above mount also looks like its flush with the back of the case.
Thanks for taking the time to measure that. I haven’t purchased the engine yet. Just want to make sure it will work in my PA-11
before I do.
 
Esp since you're planning on no electrics, seems like you'd be a lot better off just getting the approved engine (85-8).
Dunno where you're located, but good luck getting a field approval these days, at least around where I live.
 
Unless the 337 is pre-1955, a copy will not help much. The basic engines are identical. Point that out, and point out that a C-85-12 is ok, even with a C-90 crank etc., and they almost have to sign it. Start early; it takes me an average of eight months to get anything done, and I send a polite e-mail once a month or so....
.....It took me ten minutes to get a dash 12 approval for a J3.
Which is it, Bob-- ten minutes or eight months? And "they almost have to sign it"?
I guess the FSDO guy(s) I've dealt with are made of sterner stuff than yours.

IMHO doing something per TCDS or STC is almost always an easier path to yes-- even if it might cost a bit more.
 
Which is it, Bob-- ten minutes or eight months? And "they almost have to sign it"?
I guess the FSDO guy(s) I've dealt with are made of sterner stuff than yours.

IMHO doing something per TCDS or STC is almost always an easier path to yes-- even if it might cost a bit more.
Probably is simpler to go the TCDS or STC route but finding a C-90 or even a reasonably priced one is getting tough.
 
The lack of C-90 availability or prior approval is what led some like me to redo a C-85 with the Stroker STC (a C-90+ equivalent). Now, for Taylorcraft at least, there is a DER that can approve both the C-90 and O-200 in the airframes that precede the F-19 O-200 series.

Gary
 
The lack of C-90 availability or prior approval is what led some like me to redo a C-85 with the Stroker STC (a C-90+ equivalent). Now, for Taylorcraft at least, there is a DER that can approve both the C-90 and O-200 in the airframes that precede the F-19 O-200 series.

Gary
I've issued several approvals for J-3s with O-200s. I think I've done a couple TCrafts. SInce the PA-11 is on the same TC as the J-3 I don't see any reason not to do an approval for an O-200 on a PA-11.
 
I've issued several approvals for J-3s with O-200s. I think I've done a couple TCrafts. SInce the PA-11 is on the same TC as the J-3 I don't see any reason not to do an approval for an O-200 on a PA-11.
What I’m wanting to do is install a C-90-16 in my PA-11. To possibly make matters worse is that I just found out the engine is a Rolls Royce built C-90. It has its own TCDS that is verbatim to the Continental built TCDS. The Continental Tech rep that I talked to told me Continental now holds the TCDS for the Rolls Royce built engines and he assured me the two engines were identical. You would think it wouldn’t be difficult to get it approved but then again…
 
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