So I've just got my head back from the machine shop. On closer inspection I see these scallops/chunks/dents in the exhaust ports (one in every port)...
Now I never noticed them before because of the carbon coating the ports. Straight away I thought "that's odd, they shouldn't be there" so I checked with a couple of old heads I have and they don't have them.
I can't see these enhancing the flow of the exhaust gases out of the head!
BTW, the machine shop didn't make them they must have been there already.
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Sprintless for the first time in 35+ years.
... Still Sprintless.
Engines, Gearboxes, Overdrives etc. rebuilt. PM me.
1997 TVR Chimaera 450