Cliff notes version: I got the engine running tonight. I got it warm enough to open the pressure cap and dump into the catch can so it probably saw 7 psi or so. No leaks. I should be excited but I wussed out on my experiment at the last minute. Here’s the full story, sorry if its long winded...
When I pulled the head over the weekend and inspected it I reported back the oddity with the copper gasket water jacket sealing ring and it seemed like the likely cause. When I went back to clean everything up I started to scrutinize the block deck closer. In some areas around the water passages on the driver side there was discoloration on the block that looked like old rust. I stoned the block before assembly and thought nothing of it since it was flat. Now I looked at it as another source of the leak. You can’t feel it and can’t catch a nail on it but its clearly slight pitting on the deck. Here’s a photo;
https://picasaweb.google.com/lh/photo/9wLeNJpQ06K-67PkFyHU6b7Dsnwl3qS3kis-JY3pdR4?feat=directlinkThe photo makes it look way worse than it is (it also makes the machine marks look really rough as well but they also were pretty smooth). I’m an engineer by training and I’ve designed some metal-to-metal seals in the past and I know they can be finicky (sp?). Then I started to formulate the theory that if you have a flat well decked head AND block you will probably have a high success rate installing the copper gasket dry. I also figured in my head, if you have anything else you probably be opening up your chance of failure. A dry fiber gasket OR a copper gasket with some sort of sealant should seal up in those cases. So I was working on getting ready to install my head gasket DRY in the interest of science and to the benefit of stovebolters everywhere. I was mentally preparing myself for the possibility of failure and I was ready to accept that and tear down again if it happened. I was marching down that road and then something just came over me. I wussed out and put some sealer around the suspect water jacket holes on the block side of the gasket!
So I feel a bit bad but the way this project has bee going I needed something to go right. I am happy to report with the minor amount of sealant I applied it didn’t leak on the first test run. I do think there’s some interesting questions on the issue still like; is the water jacket hole an issue on the steam vented head?
As an engineer I also would love to know the data on new installed head gasket failures including which surfaces were decked, was sealant used, did the head have the steam holes, and which gasket type was used. Knowing some of that info would help sort out the theories.
I also got to wondering about the copper gasket tests designers did when coming up with the gasket design. I imagine they had a head and block decked to their flatness specification AND most likely to their SURFACE FINISH specification. People worry about flatness all the time but I rarely if ever hear anyone talk about surface finish. It’s important on metal-to-metal seals and if it’s not right it increases the chance of failure. I would bet that if I measured the surface finish on the deck of my block at the area of the photo it wouldn’t be as good as the rest of the deck even though I couldn’t tell the difference with my finger.
I’m not sure any of this info help anyone but it help to write it out, thanks for reading.
