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Burning antifreeze can pit chambers like that. Usually, with 60-70 vintage antifreeze, the pits were larger and everywhere.
 

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Discussion Starter #3
Head gasket leaking coolant into comb chamber? Exhaust side seems like it would get blown out but?? My valve seats seem good with no putting , valves kinda crusty on exhaust side, I’m thinking r/r exhaust valves , maybe replace guides on exhaust, lap all in, replace intake seals and call it a day? Surprised how good it looks (but I did do complete head job 15k miles ago..)
 

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I first saw a lot of these with the earliest 1600 101 heads that had the 101 casting number on the front of the head. These developed chamber cracks between the spark plug hole and exhaust valve seat that would eventually penetrate into the coolant jacket. The burning antifreeze caused considerable chamber pitting, usually worse on the exhaust side as it was hotter.
For your head, before I would do any rebuild work, it would seem wise to have the head pressure checked, or consider a possible gasket failure. Did it look that frosty 15K miles ago?
 

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Discussion Starter #5
Hmm.. slight void between seat and head, basically in the middle of the irregular surface....
 

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Give to a good machine shop to evaluate?
Almost looks like someone was in there with a Dremel/air tool that chattered around. I don't think it'll affect the performance a whit. Many chambers shows divots from small broken bits, corrosion, weld repairs, etc., and as long as the chambers are all roughly the same size, and the seats stay in the head, you should be OK.
Andrew
 

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That is interesting. A machine shop pressure check on that one chamber is a worthwhile investment. Could be a air pocket in the casting under the seat that is now ... cracked and leaking.
Often, leaks under exhaust seats can result in the seat being blown out of the pocket when the seat gets really hot from boiling coolant pressure under the seat. This was not uncommon with the earliest sand cast GTA race heads. The sand castings were somewhat porous, and in racing just water was used as coolant. Seats were bronze on those heads, and early exhaust valves sodium cooled. At 7000+ rpm, the water leaked under the seats, boiled, and steam pressure blew them out or loose, pistons hit the exhaust valve, snapping off the head, and the liquid sodium from the broken valve, at high temperature, with water and steam made a beautiful cloud out the exhaust. Engine builders knew EXACTLY what had happened!
Pressure check that seat!
 

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The seat looks like it is cracked, if so it must be replaced.
 

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Discussion Starter #9
ed that's a piece of wire off the wire brush -- at 9 oclock on the first close up?
 

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That is good!
 

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Do you know the history of this head? I wonder if someone previously began de carbonizing the head with a tool that left those marks, the outer part on the fire ring edge looks as though it was scraped away.
Tim
 
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