Exhaust Stack Gaskets

[Bill Gorin]

Does anyone know of an exhaust stack gasket and clamp set up for where the cylinder exhaust flanges join with the manifold that works?  Please post P/N’s and sources if you can.

Thanks,

Bill Gorin
OY-1 BuNo 03918

[admin]

Bill,

Club member Charles Rooks looked into having clamps made and he found someone who will do it, but the minimum order is 6 sets (36 clamps) at an approximate minimum price of $60 each. They of course have to be made under the owner-produced parts reg. You can contact Charles at tcraftdc65 (at) yahoo.com. Maybe we could get enough people interested if you cannot find some originals.

As for the exhaust packing that fits inside the clamp and seals the tubes, the original parts were made from braided Inconel wire and the closest thing is a Cessna 310 turbocharger gasket trimmed to size and the ends whipped together with single-strand Inconel. This is wasteful of material and is also quite expensive., but it’s way cheaper than buying a roll of braided Inconel wire.

The poor man’s solution is this…braided Harley Davidson retrofit exhaust gaskets made by James Gasket Co. They’re currently out of stock at J&P Cycles so you’ll have to hunt for them if you go this route.

These are reported to be a very a tight fit on the O-435 stacks and take some effort to get them into place.  They are not made from Inconel so won’t last but a fraction of the time in service. At $5 each or so, you could easily afford to replace them at every annual on your own bird, so someone paying a mechanic for the installation will lose the cost advantage over time.

Here is one viewpoint about using the Harley-type braided gaskets that I published about 12 years ago…

A little “Metallurgy 101” may convince some L-5 owners that stainless or copper braided wire is not the way to go. In most aircraft piston engines, exhaust temperatures range from approximately 500 degrees C. to 750 degrees C. Copper or stainless braided wire doesn’t handle the heat very well above 300 degrees C.  Inconel is a high nickel-chromium alloy specifically designed for high heat, high corrosion resistance (exhaust gases are highly corrosive), so it is commonly used for items such as aircraft turbochargers. There are various grades of Inconel that range up to 80 percent nickel. The standard 50/50 stuff can withstand 600 C while the high-grade variety can withstand 750 C.
 
Interestingly, without chromium and other additions, straight nickel can only withstand about 200 C.  Your standard stainless woven wire, on the other hand, only contains about 8% nickel and it loses its rust-resistant properties at high temperatures. The only copper type braided wire that is usable for o-ring type exhaust gaskets is Monel, which is a Copper-Chromium alloy but it is only heat resistant up to 400 degrees C. so isn’t ideal, but it is better than the stainless and copper variety. 

Jim

 

[Craig Cantwell]

I wonder if some of the graphite/inconel  braided cord could be used, with just a tapered overlay for a splice.

[admin]

Inconel/graphite flat and solid ring type compression gaskets are used in exhaust applications, so some of the braided ropes might be ok. There are also fiberglass/inconel rope gaskets used in exhaust applications up to 650 degrees C continuous.

[Sam Taber]

Hi Guys, I used Harley ( I’m live 30 miles from MKE so I kind of have to use them:)exhaust gaskets . # 17048-98. They came in pairs. Mine have lasted 1000 hrs. the fit out of the box is too tight. You must work the packing ring ( squeeze with duck bill pliers is my method) until it is slightly larger and then it fit snugly  against the stack tube wall.

The sealing surface between the bolting flange stub and the exhaust pipe is real crap for gap size and is variable due to the fit of the stubs to cyl, and mating stack. I reseal mine every 50 hrs with 106 high temp RTV. (The joint between stub and stack not the stub to cyl) .Works for about 35 hours:)

ST

 

[Bill Gorin]

Thanks all for your replies.  I spoke with Charles Rooks, and also with Bill Tromblay who reminded me that we had discussed this a few months ago.  Sucks getting old.  Bill Tromblay makes the clamps with 321 stainless steel, $300/set.  Charles said he and his IA got frustrated with the Harley seals and has used AN900-28 copper crush gaskets and has not had a leak since.

Just waiting on the clamps from Bill now.  Here is his contact info, he’s a SOPA member I believe.

Thanks,

Bill

 

[Bill Gorin]

Here are the clamps that Bill Tromblay made for me.  I used AN900-28 gaskets and they fit nice.  Bill included a set of the Harley gaskets with the clamps.

 

Thanks,

Bill Gorin

[Author]

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