Been trying O rings, quad rings really. Having some trouble getting reliable compression.
Seems there is a difference of opinion on how much pressure the o-ring should exert on the cylinder wall.
Tom Stewart calls for .005" clearance between the back wall of the piston and the ring. This is about what others, having success have told me.
Others (Pete Twissell) call for 15% compression of the o-ring. Can both be correct or is there an ideal?
I'm now going to try a regular o-ring as I suspect the quad rings are twisting in the oversize groove and loosing compression.
What a great hobby!!!
John in Wyo
axial (along length of piston) clearance. for a 0.070" seal, the axial length of groove is typically 0.089/0.099"
Pete refers to radial (across section of seal) squeeze. for a 0.070" seal, typically 12% to 15% 0.060/0.062" housing radial width. different manufacturers quote slightly different numbers.
dont worry about minor differences, its helpful to understand the principles - as extract from a leaflet above.
both radial squeeze and axial clearance are required to optimise seal performance
Does Tom refer to the diametral clearance between piston and bore? for a 0.070" seal, typically 0.005"
quad ring less likely to roll and twist, than an o-ring - of the same section width
David
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