Cutting O-rings into the block instead of the head?

[Begle1]

Machine shop guy wants to use .040" O-rings?

[ellis93]

They'll probably sink them deep in the surface to make sure they seat well. Sounds reasonable to me.

[diesel freak01]

That sounds awfully thin to me. Your gasket is prolly around .060. That wont seal the gasket if you put a cut in the head or block. Generally you want 10-15 thou crush on the rings. At least that's what we use on the tractor.


Edit
You can buy rings from sealtec if you have the sizes you need.

[RCCUMMINS89]

8 thou protrusion is usually about max.

[Begle1]

So to get 8 thousandths protrusion on a 40 thousandths ring, that'd mean the grooves need to be cut 32 thousandths into the block, correct?

I kinda get the impression that there really isn't a consensus on the best way to O-ring a block.

[diesel freak01]

This may be the difference in a wet sleeve motor and non sleeved.

[RCCUMMINS89]

Fresh back from my o ring guy: .051 SS heat/related wire, usually no more than .012 max protrusion.

[Begle1]

So does everybody install the O-rings so they press directly onto the outside of the firerings?

Without them pressing directly onto the fire-rings, I don't see how they'd work, considering that the head gaskets I have only have bare metal between every other cylinder and not a constant-thickness fiber?

http://www.enterpriseengine.com/wp-cont ... -Reinz.jpg

Are head gaskets the same for .5mm over pistons as for stock-diameter pistons?

[RCCUMMINS89]

Installed so that they crush the fire ring (causing a better seal).

[Begle1]

So like dead-center to the firerings or on their outer edge?

[RCCUMMINS89]

From what I'm used to, pretty much dead center of the fire ring.

[Begle1]

My machine shop has been sitting on this for a year because they're convinced it's not going to work.


So the concept is as follows:

Use a stock, OEM, standard Cummins headgasket.

Cut the groove for the o-ring into the block, so that the ring smashes directly into the center of the firering on the Cummins headgasket.

Press a .040" diameter stainless steel ring into a .040" wide groove .032" deep, for .008" of protrusion.

[Begle1]

I found my notes.
http://www.competitiondiesel.com/forums ... ght=o-ring

Consensus seems to be to use a .041" O-ring, cutting a groove .038" or .039" wide, .029" to .032" deep and 120mm diameter/ dead center to the stock firering.

That should put .002" crush on the ring into the block, and gives the ring .012" to .008" of protrusion.

I think I'll go with .010" protrusion since that seems to be in the middle of what everybody is saying.

[fatty]

I don't see any reason that wouldn't work.

[ellis93]

Worked out fine for the junker drag truck on compd