double orings for water seal
11-20-2005, 10:28 AM
#11
Fabricator
Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
Originally Posted by z8cw' post='779975' date='Nov 19 2005, 02:16 PM
Not sure how to check if the grooves line up perfectly but they seemed to.
As for the shape, the depth of the grooves is .06 and .054 inches, the width varies betwen .11 to.14. The OEM oring measures .084 height to .088 width. So total OEM compression room is (taking average) .125*.057 = .0071 for .0074 of oring area. That is about 4.24% of compression. Now I have twice the height so .0142 of area where I would need an oring area of .0148. That would give me a square oring of .122, a little to wide for some of the groove. I haven't made the calculation for a round ring but that might work better.
The first choice would be the square ring, but round will work fine. There are damn few round bottomed "O" ring grooves in this world.
If you have a junk housing, cut out a section with one cut beside a dowel hole. Place a piece of your proposed "O" ring in the grooves and clamp it up. This will get you an idea of alignment and volume.
So long as there is a bit of room left in the groove after torque up, it will be fine.
I add a tiny bead of silicone along the rotor side of the groove. Once the engine is torqued up, I turn it over a few times and clean out any excess silicone through the exhaust port.
The faces of the groove would have to be real close to mating, but I suspect that they are anyway. The irons are fairly weak where they cut that groove, so a hydrauliced ring would almost cirtainly break the iron.
Lynn E. Hanover
11-21-2005, 02:39 AM
#12
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Join Date: Dec 2003
Posts: 162
I can't tell you how I know, but suffice to say there is a 12A race car in the UK running FD secondaries. Now half a season of racing between teardowns vs whatever your MTBF requirements are may not stack up, but a pair of stock O-rings has been shown to hold in a sample of 1.
11-21-2005, 10:21 AM
#13
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Thread Starter
Join Date: Oct 2004
Posts: 110
Originally Posted by bill shurvinton' post='780237' date='Nov 21 2005, 01:39 AM
I can't tell you how I know, but suffice to say there is a 12A race car in the UK running FD secondaries. Now half a season of racing between teardowns vs whatever your MTBF requirements are may not stack up, but a pair of stock O-rings has been shown to hold in a sample of 1.
That sure would be the easiest. Thanks for the heads-up.
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