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Continental C90 exhaust proper hardware

sdischer

ATP, CFII, A&P
MEMBER
COLLEGE STATION, TX
What is the correct setup for bolting the exhaust to the cylinder? Nuts with split lock washers, star washers, flat washers, no washer or some combination thereof? Also what is the recommended torque? I don’t see any washers in the manual but I have seen every combination used on various aircraft. Thanks.
 
Don't know. I use brass nuts and graphite anti seize compound. I snug them up gently on to "no-blow" gaskets. Never have any problems. I machine my own brass nuts, but somehow cannot find my hex stock.
 
https://www.aircraftspruce.com/catalog/hapages/manifoldnuts.php?clickkey=3071353
21247.jpg
 
I've had the best luck with the asbestos/copper gaskets. Too bad they don't make them anymore. In 4300 hrs I've never had one blow out and I reuse them for 10 years or more. Someone had about 20 new ones for sale a while back at a flymart for 25 or $30 and I still have a supply for the next 50 years

Glenn
 
call vetterman exhaust. there pretty big fans of stainless nuts. torque-usually not below a 100 inch lbs or above 140. whatever feels good in that range.
 
and i dont know if its the correct setup or not but i use this gasket https://www.fresnoairpartsco.com/product/627429-gasket-exhaust/ with the brass nuts, with that flat surface of the brass nut in skywgons post against the exhaust, no washers, torqued somewhere in the 100-140 inch lb range. the copper gasket is also good if your cylinder or exhaust surfaces arent pristine. and theres another thin metal gasket that most double up but i havent worked with them much. some guys say they put the humps against each other and some just double them on the thin steel gasket.
 
I have always used the Continental 22022 by themselves like drawing 12242 for the power plant installation on the 90 hp PA18 shows.
 

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  • 12242 PA18, Powerplant Instl C90 exhaust.pdf
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Something else I always do when installing cylinders. With the cylinders sitting on the studs with the cylinder hold down bolts loose the cylinder has a little rotational play, maybe 1* each way. Before I tighten the cylinder bolts I put the exhaust on tight and then snug down the cylinder bolts. Then take the exhaust back off then torque down the cylinders. I use the brass nuts, they stay tight and come back off when needed. No torque wrench, just snug.

Glenn
 
That's a good idea Glenn. It gets everything as stress-relieved as possible.
 
So which is correct....double them up ? Nested to the other?, humps out?, or just single ?

Lay a straight edge on your 2 flanges on each side and see how warped they look. If still fairly thick dress them back flat and parallel to each other. One of these make it easy

Screenshot_20200201-221714.png

Glenn
 

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