Any chance you could post a close up of a single combustion chamber without the valves installed? The over the counter RAIV XC heads had completely different ports (area under the valves) than the original service heads. The 197 head looked just like the RAIV XC heads if you milled the chambers about .200 deeper. I always thought Pontiac used the same XC casting for both the RAIV & 197 head. They just machined the chambers deeper on the 197. The 7F6 and SD were both separate castings. The SD was an updated 7F6 casting and had internal support bosses to prevent cracking that was common with the 7F6 heads and RAV.
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