Cylinder O-ring questions

[lizard84]

The O-ring's , the 4 that ride recessed in the jug, do these come in different thickness's?

We are putting together my GS450/540 race engine, I 'm using a cometic head gaskit .043 thick on a 500 jug with a 450 head. For reason's I won't bore you with the jug has been milled on the bottom and then resleved.

The o-ring's are not thick enough, I don't trust stacking them one on top of another, I could shim them up with a washer under them but want to ask the race engine builder's for other ideas or advice.

Thanks

Bob

lizard84@1st.net

[sledge]

Sometimes when O Rings are used in industrial applications. i.e hydraulic sysytems, pumps and gas equipment its not uncommon to use whats known as a Containment Washer on either side of the O ring. Its basicaly a thin washer the same dia as the O Ring and its purpose is to ensure the ring is uniformaly compressed and forms an ideal seal. Containment washers are not used with the o rings on a the GS block according to my manual. Probably due to the fact the oil in the area is not at great pressure but containment washers could be a option open to you if you are looking for increased reliabilty and the seal area will accept them. O Rings are available in a variety of sizes and materials dependant on the application and are prescision made items to within 0.001"......thats as much as I can tell you about them. I would suggest you try to find a specialist supplier in your and talk to them about it.

[Bob Broussard]

I would just use the stock GS500 head gasket. I clean them off with lacquer thinner and spray coppercoat on it. If not that. Then you could use rubber o-rings in place of the stock pieces.  
Milling the bottom of the cylinders has no effect on the o-rings fitting properly. That's just a trick to get more compression.
The thickness of the head gasket is the only thing I can think of that makes the difference. The copper head gasket will compress a bit, but I don't know how much.
I suppose you could put a washer under each o-ring (in the cylinder cutouts).