LD 340 on a 318?

rumblefish360 said

72 blu, the Performer is considered 318 port size since it's ports are smaller then a 360's. Also, not all 318 heads have the same size ports. They do vary year to year, casting to casting, core shift has a play in it as well. All small potato's, I know.

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Good stuff to know though. The two sets of 318 heads I measured were within a 1/16" of each other, and that was '71 vs 80's smog heads. But I wouldn't be surprised at all if they varied more than that.

I think the Performer's are as close to 318 ports as you can get these days, but compared to the "true" 318 ports on the Streetmaster's and Street Dominator's they aren't particularly accurate. You'd have to do a gasket match to eliminate the step.