How reliable would it be to ID SBC heads as far as chamber size is concerened using the plug size as a reference? It looks like the peanut plugs might be used on the late model 76 CC chambers and the 13/16" plugs would match up to the 64 cc chambers. If this would work as a preliminary ID on a good percentage of heads, then it would be easier to find the size head I'm looking for without first pulling the valve cover. Larry

No that won't work.

All heads (as far as what came on cars) up to about 73 or so used the washer seat; all heads since use the tapered seat. There may be a few stray OTC replacement parts that don't fit this rule but this is pretty much what you'll find in the boneyards.

So there are a few OK tapered-seat ones, and spme real garbage washer-seat ones (283 3-barrel, & 307, for instance). Plus, things like 305 heads with 58cc chambers use tapered-seat plugs.

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