Rubber o-ring head
Rubber o-ring head
(OP)
I never looked much into the technical details of high performance automotive 0-ring heads. I always assumed that some of them must actually use rubber o-rings.
In recent research it doesn't appear to be the case. All the documentation and discussion on it seems to be around metal o-rings.
This got me wondering if there was a good reason not to use rubber o-rings. They are very common in dirtbikes and snowmobiles but only two strokes as far as I have found. Some two strokes run very high compression ratios to I wouldn't think it wouldn't work due to cylinder pressure but that is about the only thing I can think of that would potentially be a weakness for a rubber o-ring.
Unless perhaps it's more a matter of longevity considering two strokes get top end rebuilds much more frequently.
Just curious if anyone has seen rubber o-rings on automotive motors or other four strokes and interested if anyone has theories on why this isn't more common.
In recent research it doesn't appear to be the case. All the documentation and discussion on it seems to be around metal o-rings.
This got me wondering if there was a good reason not to use rubber o-rings. They are very common in dirtbikes and snowmobiles but only two strokes as far as I have found. Some two strokes run very high compression ratios to I wouldn't think it wouldn't work due to cylinder pressure but that is about the only thing I can think of that would potentially be a weakness for a rubber o-ring.
Unless perhaps it's more a matter of longevity considering two strokes get top end rebuilds much more frequently.
Just curious if anyone has seen rubber o-rings on automotive motors or other four strokes and interested if anyone has theories on why this isn't more common.





RE: Rubber o-ring head
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RE: Rubber o-ring head
RE: Rubber o-ring head
RE: Rubber o-ring head
je suis charlie
RE: Rubber o-ring head
http://forum.dirtrider.com/discussion/8897779/more...
http://www.ebay.co.uk/itm/2000-00-Yamaha-YZ80-YZ-8...
RE: Rubber o-ring head
I wonder what the symptoms would be of a missing o-ring?
Jay Maechtlen
http://www.laserpubs.com/techcomm
RE: Rubber o-ring head
It is definitely designed to rest metal on metal. Without the o-ring or any type of sealant it would definitely leak though.
With that said I did run my old CR250 for a while using only copper coat instead of the metal headgasket it was designed for. If I remember right it worked pretty well.
RE: Rubber o-ring head
That would be aircooled, I'm guessing.
RE: Rubber o-ring head
RE: Rubber o-ring head
RE: Rubber o-ring head
We would polish our heads on a thick glass plate with sand paper. I doubt I did more than clean up the top of the cyl.
RE: Rubber o-ring head
RE: Rubber o-ring head
There is a groove that the rings sit in so yes it should sit metal on metal plus or minus the flatness of the head and block.
RE: Rubber o-ring head
Tech specs for Regular old o-rings say they are capable of sealing 1000 plus psi if a few conditions are met.
I guess an o-ring removed a bit from the fire might be OK.
RE: Rubber o-ring head
The primary pressure seal is held closed by six sturdy studs. Rotational symmetry assures that stud forces will be evenly distributed.
Contrast that with a multicylinder engine, where there are usually four studs, sometimes five, rarely six, and most are shared with adjacent cylinders. Ensuring uniform clamping pressure is pretty much accidental, even ignoring problems associated with differences in thermal expansion between head and block.
Sealing the cylinder head junction of a multicylinder engine is a whole different deal from sealing a one-lunger.
Mike Halloran
Pembroke Pines, FL, USA
RE: Rubber o-ring head
FYI- A metal-sealing-ring approach (but with steel rectangular-section rings) has been employed numerous times to supercharged racing engines (especially dragrace) which had problems with traditional copper-gasket/metal-O-ring sealing.
RE: Rubber o-ring head
I recall seeing kalrez o-rings used as seals between the block and exhaust pipe on some 2T MC engines
RE: Rubber o-ring head
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RE: Rubber o-ring head
Another issue with o-rings used to seal coolant on one side and lube oil on the other side is the elastomer often responds differently to the two fluids. So it often requires two separate o-ring with different properties for sealing these joints.