o-ringing t-stat housing

I'm going to take my thermostat housing to work and o-ring it to make a better seal. how much of an o-ring needs to protrude for proper sealing?
like 1/4 of the cross sectional diameter?

it's the chrome housing, and when i put it on, i sanded the bottom face with 120-grit to make a good seal surface, and it sealed for a good while, but now it has gottem moist around the seam. it looks like the gasket is saturated and seeping, but i'm just going to machine it for an o-ring and forget it for good.

You can buy Chrome ones already machined for a O ring. However after awhile the corrode and the O-rings doesnt fit right. I'll never run a chrome one again. They always leak.

Green Cuda
I am having the same problem on my new 340 in my 69. the chrome t-stat housing just wants to leek.I had it off 3 times and even sanded it like you to no avail.
I found that the ends where the bolts go thru would bend downward,and on the manifoid, the metal around the bolt holes would pull up.I flat filed the maniflod, using magic marker to check it, and I did the same on the housing.I would put both pieces together and rub them, and where the marker comes off that is the high spots.When I first started doing it the housing would really wobble on the manifold. I'ts kind of a slow deal but it has worked for me so far. You can still use sand paper in the process to. the housing would rock back and forth like it was warped.when I stated.
After I got it Flat I put a beed of blu RTV all around the manifold and around the housing with the gasket between and bolted it together, and torqued it down, And it hasn't leeked yet. Might give that a try. Dave

green67cuda, here is the info you need to add a static gland, go for the -200 series o-rings for the housing and shoot for 20% squeeze. You'll need to do some home work for o-ring capability, but Viton or Buna-n should work fine.

http://www.marcorubber.com/glands_static_axial.htm

green67cuda, here is the info you need to add a static gland, go for the -200 series o-rings for the housing and shoot for 20% squeeze. You'll need to do some home work for o-ring capability, but Viton or Buna-n should work fine.

http://www.marcorubber.com/glands_static_axial.htm

Geeez.... who ya think yooze talkin to here? That's some mighty tek-nic-al stuff you posted! :sleepy3:

All kidding aside, I love seeing stuff like that turn up when people request an answer to what seems like a simple question. Welcome aboard Dano. :headbang:

When I bought aftermarket chromed themostat housings, I could never get one to not leak. I purchased a cast iron housing and sent it out and got it chromed. I never had a problem after. Later after a few years as a precaution I purchased a Proform rubber gasket that has a built in "O" ring. It's been in use for about 20 years removed about 5 times and reinstalled, and I've still never had a problem.