In reply to Frank’s question, the ports are for connecting hot exhaust gases through piping to provide heat to the intake manifold (original or aftermarket). Without this heat, you can expect poor performance at best.

Here is a link (not mine) to one of many sources for such a piping kit: Fenton Header piping kit


~ Dan
1951 Chevy 3 window 3100
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"My Grandpa Carl's Truck and How it Became Mine"
1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver)
US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)