gt-40p and thermactor drilling...How?

homeroV8 · 11-18-2002, 06:42 PM

If my gt-40ps aren´t drilled for the thermactor air passage, can I drill them in the same place as the stock heads? How far can I go?
Or I can leave it this way and disconnect the smog pump? No need for emissions on my location, by the way.
I would appreciate any comments.

squid · 11-18-2002, 11:25 PM

I have been wondering this same thing. I figure it should be a simple drill and tap into the same location in the head as the stock mustang heads but would love to hear someone with personal knowledge verify this before I make swiss cheese of my heads. I know Central Coast makes this modification but havent heard any of the details. Hope you get a response!

Jeff Chambers · 11-19-2002, 08:02 AM

If you don't have emissions in your area, then don't worry about it. Just ditch the smog pump and cross-over. Cap/plug the air tube to the H-pipe and awayyyyy you go.

Fox Hound · 11-19-2002, 11:59 AM

Here's another vote wanting to know how this is done since I'm in California, home of the smog police.

Jeff Chambers · 11-19-2002, 01:06 PM

To pass the smog police here in the NE Ohio area, I bolted the air pump and cross-over on for the test. The thermactor holes have never been drilled on my heads so the pump was basically dead-headed during the test. I didn't even haven the air tube connected at the H-pipe, it was just hanging there free. The car still passed the dyno test with flying colors. At the time, I was running a 224/232 cam with 110 CL and 30# injectors.

homeroV8 · 11-19-2002, 05:02 PM

Simple as that? The car will run and idle just fine?
But, if I had to drill, is anything I should be aware, or I can go deeper into the head?
Thanks for the info, I really appreciate that.

John · 11-19-2002, 09:08 PM

The hole in the head for thermactors is actually connected to the valve cover bolts, stick a pick into the hole see how deep it is, and use this to determine how far you need to drill. Also if no holes for thermactors are there then why would the hole or tube as some would call it be there

Jeff Chambers · 11-20-2002, 07:47 AM

The P's aren't drilled from the factory. The EGR passage is probably a remnant of the original design and casting molds, but since the later model Explorers didn't use the thermactor passage, Ford simply cut one of the last production processes which was drilling of the crossover passage as a means of reducing cost. The Explorers took the injected the air directly into the exhaust manifold instead of through this thermactor passage.

Personally, I wouldn't drill it even if I lived in CA. If the smog police want to see the cross-over in place, then just simply bolt it to the back of the heads.

homeroV8 · 11-20-2002, 10:10 AM

Thanks again, I´ll probably let it alone. All I gotta do is a little polish and porting work (cut the exhaust thermactor bumps, etc.)
Lol, as you see I´ve been studying...

11-18-2002, 06:42 PM	#1
homeroV8 Registered Member Join Date: Jan 2002 Location: Orlando, Fl Posts: 37	gt-40p and thermactor drilling...How? If my gt-40ps aren´t drilled for the thermactor air passage, can I drill them in the same place as the stock heads? How far can I go? Or I can leave it this way and disconnect the smog pump? No need for emissions on my location, by the way. I would appreciate any comments. __________________ black 95 GT, 5 speed, MAC catback, BBK o/r h-pipe, FMS 3:73, GT40P mildly ported and polished heads, MAC p-headers, roller rockers, mildly ported and polished cobra intake, XE270 comp cam, 65mm Tb, 77mm Pro-M.

11-18-2002, 11:25 PM	#2
squid Registered Member Join Date: Sep 2002 Location: Dayton, OHIO Posts: 73	I have been wondering this same thing. I figure it should be a simple drill and tap into the same location in the head as the stock mustang heads but would love to hear someone with personal knowledge verify this before I make swiss cheese of my heads. I know Central Coast makes this modification but havent heard any of the details. Hope you get a response! __________________ 93'GT 5spd. Underdrives, FMS clutch, adjustable quadrant,Flowmasters, Kenny Brown subframe connectors, 3.73 gears, Steeda Tri-Ax. JBA shorties, BBK h-pipe. More to come.

11-19-2002, 08:02 AM	#3
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	If you don't have emissions in your area, then don't worry about it. Just ditch the smog pump and cross-over. Cap/plug the air tube to the H-pipe and awayyyyy you go. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

11-19-2002, 01:06 PM	#5
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	To pass the smog police here in the NE Ohio area, I bolted the air pump and cross-over on for the test. The thermactor holes have never been drilled on my heads so the pump was basically dead-headed during the test. I didn't even haven the air tube connected at the H-pipe, it was just hanging there free. The car still passed the dyno test with flying colors. At the time, I was running a 224/232 cam with 110 CL and 30# injectors. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

11-19-2002, 05:02 PM	#6
homeroV8 Registered Member Join Date: Jan 2002 Location: Orlando, Fl Posts: 37	Simple as that? The car will run and idle just fine? But, if I had to drill, is anything I should be aware, or I can go deeper into the head? Thanks for the info, I really appreciate that. __________________ black 95 GT, 5 speed, MAC catback, BBK o/r h-pipe, FMS 3:73, GT40P mildly ported and polished heads, MAC p-headers, roller rockers, mildly ported and polished cobra intake, XE270 comp cam, 65mm Tb, 77mm Pro-M.

11-19-2002, 11:59 AM	#4
Fox Hound Registered Member Join Date: Nov 2001 Location: Bay Area, CA Posts: 58	Here's another vote wanting to know how this is done since I'm in California, home of the smog police.

11-19-2002, 09:08 PM	#7
John Registered Member Join Date: Dec 1998 Location: Ft.Myers, FL. Posts: 150	The hole in the head for thermactors is actually connected to the valve cover bolts, stick a pick into the hole see how deep it is, and use this to determine how far you need to drill. Also if no holes for thermactors are there then why would the hole or tube as some would call it be there __________________ 89 Notch: 10 pt. cage, d&d rear coil overs, moser 33 plines and spool, gutted 91 Hatch: cobra int. fms. c-springs, novi-1000 w/f-150 crank pulley (9lbs.) 06 F-350 6.0 crew cab lariat srw 4x4: turbo back exhaust, sct xcal.

11-20-2002, 07:47 AM	#8
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	The P's aren't drilled from the factory. The EGR passage is probably a remnant of the original design and casting molds, but since the later model Explorers didn't use the thermactor passage, Ford simply cut one of the last production processes which was drilling of the crossover passage as a means of reducing cost. The Explorers took the injected the air directly into the exhaust manifold instead of through this thermactor passage. Personally, I wouldn't drill it even if I lived in CA. If the smog police want to see the cross-over in place, then just simply bolt it to the back of the heads. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

11-20-2002, 10:10 AM	#9
homeroV8 Registered Member Join Date: Jan 2002 Location: Orlando, Fl Posts: 37	Thanks again, I´ll probably let it alone. All I gotta do is a little polish and porting work (cut the exhaust thermactor bumps, etc.) Lol, as you see I´ve been studying... __________________ black 95 GT, 5 speed, MAC catback, BBK o/r h-pipe, FMS 3:73, GT40P mildly ported and polished heads, MAC p-headers, roller rockers, mildly ported and polished cobra intake, XE270 comp cam, 65mm Tb, 77mm Pro-M.