turbogrill Posted May 23, 2017 Report Share Posted May 23, 2017 Hi, I have a head that is supposed to work just fine. While inspecting it there was a tiny crack in a coolant passage. The crack goes away from combustion chambers and towards what I believe is the hole for the head bolts. If the crack would get much worse what would happen? Just ignore and continue? Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee hornerevan Posted May 23, 2017 Technical Advisory Committee Report Share Posted May 23, 2017 Nope. That head is garbage. Seeing as you run a Z and heads are likely hard to come by, you could consider taking it to a machine shop to have that crack welded and the passage remachined. Quote Link to comment Share on other sites More sharing options...
Hi_Im_Will Posted May 23, 2017 Report Share Posted May 23, 2017 That's probably trash. You can try milling out the crack itself to eliminate the stress riser, and the result might be OK for a street car, but I wouldn't run it in a race. As soon as that crack crosses over to the head bolt, it will push water up the bolt shank and into the oil. 1 Quote Link to comment Share on other sites More sharing options...
mender Posted May 23, 2017 Report Share Posted May 23, 2017 Or drill a crack stopper hole. 3 Quote Link to comment Share on other sites More sharing options...
turbogrill Posted May 23, 2017 Author Report Share Posted May 23, 2017 3 minutes ago, mender said: Or drill a crack stopper hole. So wouldn't coolant eventually find its way to this hole? But that would be fine? It would just sit there? There is plenty of material around. Quote Link to comment Share on other sites More sharing options...
mender Posted May 23, 2017 Report Share Posted May 23, 2017 (edited) Reassessment time after looking at some pictures of a 240Z head. Right between the two centre exhaust ports. That could be an issue and also the reason for the crack in the first place. Edited May 23, 2017 by mender Quote Link to comment Share on other sites More sharing options...
Hi_Im_Will Posted May 23, 2017 Report Share Posted May 23, 2017 12 minutes ago, mender said: Or drill a crack stopper hole. That's a much more elegant term for what I was trying to say. 1 Quote Link to comment Share on other sites More sharing options...
mender Posted May 23, 2017 Report Share Posted May 23, 2017 2 minutes ago, Hi_Im_Will said: That's a much more elegant term for what I was trying to say. If it works; looks like it's between the two centre exhaust ports, so might break into one of them or cause more issues. I'm thinking that your original assessment (trash) is more likely the right one. 1 Quote Link to comment Share on other sites More sharing options...
turbogrill Posted May 23, 2017 Author Report Share Posted May 23, 2017 2 minutes ago, Hi_Im_Will said: That's a much more elegant term for what I was trying to say. haha ok! I will have a head expert have a look. I have another head but it's not ported so it would be nice if I could use this one. The Z needs a decent head if you want to pass a stock NA miata on the straights 3 Quote Link to comment Share on other sites More sharing options...
mender Posted May 23, 2017 Report Share Posted May 23, 2017 Do some chamber work while you're at it, they like a little room around the valves. Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee hornerevan Posted May 24, 2017 Technical Advisory Committee Report Share Posted May 24, 2017 But a non-ported head that allows you to finish a race is better than a ported one that doesn't. Quote Link to comment Share on other sites More sharing options...
turbogrill Posted May 24, 2017 Author Report Share Posted May 24, 2017 4 minutes ago, hornerevan said: But a non-ported head that allows you to finish a race is better than a ported one that doesn't. That is very true Quote Link to comment Share on other sites More sharing options...
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