MustangWorks.com : Ford Forums - View Single Post - gt-40p and thermactor air

7000rpmisheaven · 11-11-2002, 05:57 PM

There is a thermactor passage in the back of each head. They are there for emissions. The GT-40Ps came on the explorers and are are set up to be an emission legal head. Some aftermarket heads don't have the passage and you would have to remove the smog pump and some of the stuff with it.
Having them won't make a noticable change in performance. I you need to stay emissions legal I would stick with it.

11-11-2002, 05:57 PM	#2
7000rpmisheaven Registered Member Join Date: Nov 2001 Location: germantown MD Posts: 283	There is a thermactor passage in the back of each head. They are there for emissions. The GT-40Ps came on the explorers and are are set up to be an emission legal head. Some aftermarket heads don't have the passage and you would have to remove the smog pump and some of the stuff with it. Having them won't make a noticable change in performance. I you need to stay emissions legal I would stick with it. __________________ 85 GT 4bbl roller cam 2 ch. Flowmasters, O/R H-pipe Performer intake and carb milodon water pump, FMS 9mm wires, aluminum driveshaft, king cobra clutch