Good phenolic spacers are widely available, Summit, Jegs, etc all have them. Use the largest that will fit, I ran the 1/2" 4-hole model to promote velocity. The B2 spacer is unique in that it has a metal tube exiting from the front of it that runs to the PCV in the rear of the right hand valve cover. In terms of insulating properties, there are much better spacers now available. Good luck..
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