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C-85 stroker

Tx
Hey guys, I keep hearing people talking about a c-85 stroker, can you guys fill me in, what does it consist of?

Also, what's the most bang for the buck if you will for a j-3?


Thanks
Tom
 
Tom,

Best bang for the buck is a good C-90 with a good crank. C-85 stroker is a C-85 with a C-90 crank and pistons.

You can look for a complete C-90 or start collecting parts. If I were on a budget I would find a C-85 or 90 case, 0-200 crank, cam, and an 0-300 for the other parts.

Tim
 
I'd do a search on the site for the stroker- there's a fair amount of info on it.


I have one on my J-3, and the fun factor with all that power in a light airplane is really hard to beat.
 
Now can I use a c-75 case for anything of it?

C-75 case is good to build up a 90 or 85. 75 crank is the same as an 85.

Just make sure it is a C series, not an A series. Lots of people write their cub has a C-65 when their cub has a continental A-65 (or A-75).
 
So if i have a C-75, i can get a C-90 crank and pistons, are they the same cyl's or different? Also is it an stc for this mod? is that the "stroker" i am hearing about

Thanks
Tom
 
Best bang is what you have, vs. what you can spend. C-90's are great, but tough to find without spending big $$$; O-200 are great because you can find them anywhere, but the cam doesn't make power as good. Super-85's combine the best of both; power of the C-90, and availability of the O-200.

Fairly certain you have to use a C-85 case; my copy of the STC only mentions C-85's NOT the C-75. I'm sure it can be done, but to make it legal will require a 337/field approval. Same thing with using C-90 parts; they're not listed in the STC.

The original STC had you use a C-85 core, with O-200 crank, rods and pistons. But, if you have a good O-200 core, you can combine a couple different STC's from Don Swords and use an O-200 case, crank, rods, pistons, gears, and cylinders with a C-85 cam and achieve the same thing. Basically an O-200 with an 85 cam. All done legally.

If you're serious; best thing to do is call Don Swords with specific questions about what parts you have on hand. He can tell you what will work and what you need to finish.

Good luck; it's a sweet-heart of a motor.

nkh
 
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Note that the C75 and C85 cams are the same. 0200 innards and your on your way. Afraid of that 125 Franklin? Jim
 
I'm flying 2 different Strokers right now, one in a J3 and one in a J4 and they both run great,but my pa11 was a C90-8 that was really a -8 0200 because it had the 0200 cam and timming. C90 and 0200 share the same crank, rods, pistons and cylinders. I think if I did it all over I would just use a 0200 with the correct prop that lets it turn 2650+ on takeoff and in a 650 lb J3, J4 or a pa11 would be tough to beat off the ground at 5 gal an hour. The great thing about the C85 stroker is that it always stays a C85 even though it's 0200 parts and it makes the paper work very easy. If you want to save more pounds DDM can make a 0200 case into a -8

Glenn
 
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Cylinders stay the same as on -75 right?

Thanks For your help guys, i never seem to have any luck with the search feature

Tom
 
Cylinders stay the same as on -75 right?

Thanks For your help guys, i never seem to have any luck with the search feature

Tom

Tom I just talked to Don, as long as it's a " C75 " it's doable, not a A75, C75 needs to be changed to a C85 which he said is easy and the main jet and venturi need to be changed. You should call him and he will tell you what you need to do 770 412 8885. The big problem right now is the shortage ( none ) of 0200 cranks

Glenn
 
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C-75 through O-300 cylinders are all the same. There are different valve springs for different applications, but the physical cylinders are all the same.

nkh
 
There is continental documentation on going from a c-75 to c-85, FYI.

The interchange manual is also a continental document, FYI.
 
Out of interest if one was to do the stroker conversion on a C85 would one have to modify the carb? In this case a stromberg carb
 
I'd consider using whatever carb specs are required to meet TCDS E-252 for the C-90 with a Stromberg. The STC's don't address a carb change however. Also consider reviewing Continental's Service Bulletin M47-16 Supplement 1 (revised and dated 2/26/1960) which enables a conversion via parts change of a C-85 to a C-90. It's exclusive of the current STC's for that similar process. Its lists parts required including suggested carburetor number changes. I can send you a copy via e-mail if you can't locate the data.

Edit: Also consider asking this facility about the need for carb changes with STC'd increased engine displacement: http://thestrombergspecialist.com/index.php

Gary
 
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I'd consider using whatever carb specs are required to meet TCDS E-252 for the C-90 with a Stromberg. The STC's don't address a carb change however. Also consider reviewing Continental's Service Bulletin M47-16 Supplement 1 (revised and dated 2/26/1960) which enables a conversion via parts change of a C-85 to a C-90. It's exclusive of the current STC's for that similar process. Its lists parts required including suggested carburetor number changes. I can send you a copy via e-mail if you can't locate the data.

Edit: Also consider asking this facility about the need for carb changes with STC'd increased engine displacement: http://thestrombergspecialist.com/index.php

Gary

Gary, he will tell you its not airworthy till he looks at it. And want 1k+ to look at it, Even if it was NOS. Simplest carb ever built
My stroker is running same carb as before stroked.

Glenn
 
Gary I tried that cover for about 20hr one winter. I just cuts down on the amount of air entering the filter. The reason it works for some is that they are already running too lean and add the cover to make it richer. Mine ran better without it, on 3 different carbs. Simple to learn how to adjust the mixture for the season of the year

Glenn
 
Thanks Glenn.....I never used one of those covers but a local T-Craft did and reported it ran better until he stuck a valve. Oil was black from rich mixture so maybe it does work miracles. One noteworthy thing is the recommendation in that SB to close then reopen the throttle on Strombergs if the engine quits. Helps suck fuel better when closed like when hand propping. Takes real resolve to close the throttle while staring at the cows getting larger.

Gary
 
On anything with a combustion engine that straves for fuel your only chance of keeping it running is to reduce the air flow most times. But your right on the Stromberg, closing the throttle all the way gets gas flowing thru the idle circuit

Glenn
 
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