Looking at the picture , the o-ring depth looks pretty deep.

Is the o-ring really needed ?It does look to be groove deep.

The depth of the groove is based on the section of the o-ring.
I'd suspect that they are using a pretty thick section on the o-ring to keep the thing strong enough to not get torn while stuff is moving around.

I o-ringed the AR376 SB plate. If you look close you can see that I o-ringed the timing cover also. It is an expensive process for billet parts. I'm not sure how the OEM's make the o-ring parts in production. They must have some special tooling to keep the cost down.

O rings are for sure nice, and no clean up swapping stuff around. I'm always in too big of a hurry to go to the track lol.

I've seen more than I can remember, days ended early from gaskets, and motor plates, on all makes. Just seems like an unnecessary risk to me.

Like mentioned, big blocks probably have the worst issues because the only mounting points are the 3 bolts on each side of the block outlets. Just add a tension rod from the lower left corner of the block or timing cover, and come up at about a 45 degree angle to the front plate. That will greatly decrease shearing motion at the mounting flanges for the coolant passages.

I'm an o-ring junkie. I o-ring anything that I can because its just so clean and does a great job of sealing. No mess to clean up when taking apart! I have yet to have anything leak that I have o-ringed as long as the o-rings are fresh (replaced the o-rings on the valve covers after about 12 years - they were due).

There are several configurations of o-ring grooves. The one I use is quite simple but has served me well. The groove dimension is straight out of the Parker o-ring manual. The one negative on this type of groove is the o-ring is loose and you have to use a dab of grease to keep from falling out during installation.

With my new cnc I am tempted to experiment with different types of grooves. Might on future projects.

Harvey Tool makes dovetail o-ring cutters that capture the o-ring. Just drop it in, run the circle one way and then run it back the other way.

http://www.harveytool.com/prod/Dovetail-...lowance_81.aspx

I keep this in my phone, as I too, am an o ring junkie...

Quad orings are great for sketchy surfaces too. I use them on hemi spark plug tubes. Kinda like having 2 orings in the same space as one.

The charts shown are correct for o rings and quad rings. O ring “dash” numbers are equivalent between the two. Back up rings also follow this numbering system. The dash number indicates size. The prefix to the dash number determines material and form.
A great resource for o rings is McMaster Carr. You can find size, material, form on thier site, and the price for a typical bag of 50 rings is usually in the $7.00 range.
Sorry if this derails the topic, but I thought it could be of use.

After the machining process o-rings are a lot cheeper than gaskets .

Andy - thank you very much! I had not seen that solution before and its looks great! I plan on getting one to try.