You used the key words "street machine". I have no experience with any hi-perf AMC's, but I did once run a chev 283 w/30-30 cam +solids, .040 over and 10 to 1 comp. I blocked the crossover with a Mr. Gasket intake set, and with a Holley four, I found it very disconcerting to find , in cool, humid weather, that the throttle would freeze up at part throttle while just cruising. I had heard of carburetor icing, but just in airplanes. Gets exciting when the car won't slow down with foot off gas. I suspect you may find some of those manifolds may not have a crossover passage, anyway, and the heat from below through the aluminum plenum may be adequate. More experienced will chime in, I hope. Just that if you get the NON-crossover type heads, you are stuck in that rut. I will say that my chev ran great during the summer, never needed premium, only regular gas. Glenn Ford _______________________________________________ AMC-List mailing list AMC-List@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list or go to http://www.amc-list.com