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I have a set of heads off of a 69 Z28 (casting # 3827186). I had these heads magnafluxed at a local machine shop and they found a crack in the water jacket on the exhaust side of one of the heads. The crack is horizontal, about 2 inches in length. I wanted to have these heads rebuilt to use on my 72 Vette. Would it be safe to have the crack welded up and use these heads or would It be better to find another set of heads?
I can't answer your question on the possibility of repairing the crack, but if it's not repairable, the service replacement is available. I ordered a set this morning from Jim Pace (www.paceparts.com). The casting # is different, but I believe it is the same head.
I had a set of all done up 186 double humps. Max porting with 2.02/1.6 Manley raceflow valves dual 1.46 springs screw in studs and guide plates. I took them off my car many years ago. Well I decided to sell them. So I took them to the shop for a total refresh and durring magnafluxing. They found one hairline crack from the exhaust seat towards the quench area. I had no idea and they came off of my vette.
Well the shop gave me the "We can fix them with no guaranty speech" So I just gave them the heads. I couldn't sell them. I went in a year later to have some other set refreshed and they did it for free. They said that they repaired and then sold my 186's to a kid with a 383 and 100 hp spray kit and he loves them.
They might be able to fix them. Or call around maybe you can find one somewhere. There are so many low priced iron modern performance heads. that i would never spend a bundle on old tech.
Thanks, I found a guy who said he could fix the crack and guarantee it would be ok. Cost $40.00. I think I'll go with screw in studs and guide plates too. I haven't decided on a cam yet but I'd like for the studs to be strong enough for a high lift. By the way, the casting # is 3927186, not 3827186. I'm not the best typist in the world. :D