nos 289 HP thermactor heads

They are over the counter service replacements heads. They did not come on any assemblyline car I am aware of .Bob

 

Agree with Bob on them being replacements - interesting that Ford thought there was a need for these heads (since they were only used for a few months of production for cars only being shipped to one state) as late as 1973

Just interesting IMHO

 

More likely the Thermactor-capable heads superseded the non-Thermactors, much as the Thermactor type C7ZE manifolds replaced the C3/C5OE. They would simply have used the plugs to seal the injector holes when they were not needed. The fact that the Service Replacement heads had inferior flow to the earlier design would not have been a consideration for the Service Parts Division. They all sucked anyway, the single best thing you can do for any 289 is open up the exhaust ports.

 

Of course the C7s were not the only service replacement heads carried during that period though. Not a big issue since I think we all agree that they are not factory on anything