The Stovebolt Site Forums The Shop Area Engine Shop 1936 cracked head

Discovered a cracked head in my 206 engine. Looks to be hair line from # 3 (thought #4 at first)cylinder to the outside of the head on the passenger side. It feels like it penetrates the water jacket in the center of the head thus explaining the foaming radiator. The rhymatic pop pop pop must have come from the exit point under the side cover. Maybe it can be welded and the head milled. Think the block should be decked? Don't know why the head cracked unless it was not straight. I didn't torque those head bolts so I don't know if the builder did. What about new head bolts? Don't have much experience with these low compression engines, stove head bolts, and welded heads. Any info would be appreciated.

Does the crack go across a valve seat? Any good machine shop should be able to pressure-test the head and tell you if compression is getting into the water jacket. There is a repair procedure known as "stitching" which involves installing a series of overlapping threaded cast iron plugs along the crack that is sometimes more effective than welding depending on the location and the severity of the crack. The process isn't cheap, but it's pretty effective. If the crack involves a valve seat, the seat will have to be machined away, and a new seat installed after the crack repair.
Jerry

Thanks Jerry. No valve seats involved unless there is another crack that I don't know about. Probably should have it magnafluxed to find out for sure. It does go into the water jacket as best I can tell. I can stick my finger and feel what appears to be a crack in there just opposite the head surface. One fellow at a machine shop mentioned stitching. Will probably take the head to him and get a read on it next week. The engine has all new gaskets on it and is painted so it may have been totally rebuilt. I wonder if new head bolts are available for it. Old bolts have, in my experience, led to blown head gaskets due to their elastacity being compromised. Allen

sometimes you can find NOS bolts, but unless they are completely ruined you can use them over, think about how little is actually going on in one of these engines. What is it, 5-1 compression, at 3500 RPM max? Not a whole lot more stress than a briggs and stratton. But the deciding factor will be if you can find them or not. And you can check for yourself, but when I checked, ARP can't get all the sizes you need. However I was also looking for main cap bolts too at that time. Maybe it was the mains they didn't have (?) I ended up with studs at any rate. I had a 1936 206 head for a long time, but sold it recently ....

If you are looking for another head, you may have some luck with the people on the VCCA website. They have members that have some good NOS stashes.

If it comes down to replacing the head I know of a few 36 heads.

There is a head repair shop in Jackson that I am going to talk with this week. Will go from there. Thanks for the info.

The repair shop showed me the "stitching" method of head repair. It looks like a workable solution but not one that I elected to use. The head was really warped and had signs of severe over heating and evidence of cross leakage between cylinders. Over heated engines are not something that bring pleasant memories to mind. Looks like another engine is in the picture and it will probably be something that will run on the interstate. Allen

If you decide to go with a 235 I can tell you what is needed to install it and keep your stock transmission.

That is something that I am considering. I have access to a 1955 chevy truck 235 with transmission attached. What j think? allen

A 235 is a great option, changing from the 36 trans would involve more work. Is this a 1936 truck or car?

36 truck. Would a 250 or 292 work and how about an automatic? It is my wife's truck and she wants to drive it a lot. Sorry about late response but had to work and will be out of town for the next 3 days. Appreciate your response. Allen