Do later big block heads have those small ports by the exhaust? I remember hearing about these ports needing to be plugged on small blocks, but not sure about bb heads.

If they do have them and they're not plugged, what is the outcome?

Any way to determine if I've got them without taking the headers down?

Thanks, and happy holidays.

-Pat

dont think they had the holes in the heads

I think the airpump pumped it into the manny in it own passage then mixed fresh air with the exhast on the way out

that was mopars way of deluting the exhast with fresh air to lower emission at the tail pipe/sniffer

i do know most of the SB that have injection holes are most times pluged from carbon anyways

only had one that leaked with headers when I did not plug them

so I just drilled tapped the one hole

but after the rebuild and VJ,they were all open but the one pluged hole

I've never seen them on a big block head .

on 72 400's the air pump put air into the exhaust manifolds.
i know this for a fact on 72 road runner 400 motors. i have a set of manifolds and the matching air pump and lines that i helped remove them myself from a California emission car.

some SB are like that as well

pumps air into the manny

other pump air THRU the manny in its own passage into the injection hole and into the exhast port floor

My 72 Imperial is a CA car. It has a smog pump blowing air into the front of the passenger side manifold. I can't see where it goes into the driver's side manifold. The hose is disconnected and plugged. The manifold may have been swapped when they replaced the exhaust.