I have a 355 sbc that is running an Eagle crank & rods connected to TRW flat top pistons with a typical flat hydrolic cam & Lifters. The cam is for a super charger. I have been running a B&M 144 street blower for a few years The heads are cast iron 190 intake from a Merc Marine 350 not sure of the chamber size. This all sets in a 1947 ford convertable. Here is my problem I ran across a deal on some brand new alum. heads that have the 202 intakes and I think the chamber size is 64. The engine now cranks hard (I do have a high tourq starter) After it starts I have lots of spark knock that I didn't have before, if I advanve the timing it will not start, If I retard the timing it will not start.