ACH's heads country of origin is unknown, but I highly suspect China, as I've had a set of their heads. The heads are assembled here in the states using used valves and components. That's why they WANT the core back regardless of the condition of the casting.
When they first got in the game I saw a set on eBay pretty cheap, so I bought them. They had a no haggle return if I wasn't satisfied.
Well, I didn't like the machining on the surface of the heads, and the fact the precombustion ports were machined in the heads (with the surface grinder). They're not even stainless steel precups, who knows what they are. Probably that same pot metal crap that was used to make the GM heater quick connect fittings that breaks on every engine...
Anyways, I sent them back.
Now, there are about 10 different head shops selling different (or the same) reproduction heads.
The sales pitch is always the same too, "we increased the thickness in all the areas that crack to make them stronger." Ha, ha, ha! When you make the surfaces thicker that crack it can make the problem worse. From what I understand most cracking is due to uneven heat transfer, among other things.
They supposedly increased the thickness of the walls on the port that goes between the valves. Can't say this is the right move or not, but I suspect not. The crack always starts on the edge of the seat, exhaust valve primarily. So the cooling port being smaller isn't going to make any real difference, except that it'll take the crack longer until it get's to water. The crack will probably still occur. The real issue is the induction hardening on the seats, the crack starts here.
Rant off...
Still looking for Canada castings.
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Originally Posted by john8662
