Head studs leaking coolant

[Jim B]

One area you might want to double check is the tap you used to chase the block threads. I've been told some of the imported tap and die sets are poor quality and finish the thread outside of tolerance creating a "loose" thread engagement pattern. I might also have a machinist check the thread on the head studs (I kind of remember good block studs utilized a "close tolerance" thread on the block side) Did you chase the stud threads with a die as well? I would also double check the stud thread height to be sure you are not bottoming the nuts against the stud thread base instead of clamping the cylinder head. (a thicker head stud washer on severely milled cylinder heads may be necessary) By your post I'm assuming the block deck bolt holes aren't heli-coiled and the deck surface/threads aren't showing cracking. I wouldn't rule it out but it seems odd to me that the ARP sealant can't seal their studs unless there is a bad batch out there.