Why The Smog Pump On A '75??

USA Federal emissions requiring cats started in 1974. why would it not have an airpump? California sold cars also had stricter emissions stuff in place at least one year earlier than other States. i grew up in California in the late 70's. i remember all this crap from when it was the norm.

 

Air injection started being required/appearing in the late '60s (~1967?) in the US -- even US 246 Dino have it.

 

Smog pump and injection rails are required as part of original equipment. However, if it malfunctions, or if it is missing, then it becomes "impossible" to reinstall them because 1) they are no longer available from dealer, and 2) they cannot be purchased from the state-sponsored used equipment sources. Therefore, you will get an exemption from the referee.

You can refuse to put on an aftermarket, or GM pump on the ground that it was not designed for your car.

This is all moot for 75 anyway because it is exempt from testing. You are not supposed to remove the stuff, but your 75 or earlier is not tested at all.