[Tony Wheeler]

Just out of interest (and for the non-believers!) here's the full flow system shown in the CMP manual. A bushing separates the vertical and horizontal passages, and a third passage is drilled for the filter return. This third passage will be found on all CMP motors but not on standard flatheads.









Decades later the hot rodders developed a similar modification using a grub screw to separate the vertical and horizontal passages, and a third passage drilled manually. Evidently they're not aware it had already been done on the CMP. As mentioned though it's always plugged in my experience (but not with a bolt like I did on my first blitz!)