i decided to port my heads....jsut as everyone has said to do....and i looked at the intake port.....they look real good and smooth....nothing to do....so i look at the exhaust port....and there is a huge hump right there.... everyone calls this the thermactor hump right?? well why is there a water port in this thermactic port..?? i grind it off..jsut as everyone says to....and there is a little hole...1/4 x 1/4 or so...i think..oh its just becasue the thermactic hump is hollow...well i ask a freind who ported his heads ....he said the thermactic hump is suipposed to be solid...not mine i tell him hmmm he says....should be solid.... i stand the head on end i go and get a syringe and pour water into it....the water comes out the exhaust port at the bottom....WTF??? then i tip the head over and water comes out the water port going into the intake manifold... ok...so now i need new heads....i wish i had known that this hump cannot be ground down... FYI D5OE casting on the bottom of the head....and 302 in valve cover area...
I always grind out the Thermactor bumps...all the way down to the roof of the port. Not all heads are the same, but on every one that I've done (probably 10 sets) I've never run into that problem. I even grind off the exhaust valve guide boss...completely. Are you sure it's just not water coming out of the thermactor holes in the end of the head? I haven't seen the D5OE heads, so I can't say for sure....
Just had a look at my heads (D2OE's) on my bench and no bumps left but I can't recall if these had them now or not, it's been about 10 years since I did them, so if they had the thermactor bumps they're gone now.
yeah ...there is a threaded plug int he head right where that air would plug into....so do i leave the holes alone in the exhaust ports....or are the heads junk and go get some new ones... they are 1975 heads...i thought 1976 saw the emissions stuff
You can leave the holes alone. Just make sure water is not going from that passage to the water jacket.
i loked again....and i think it is jsut the air port....not connected to a water jacket...i hope.....but if using emissions equipment...they would be open...so i dont think it will harm anything leaving the holes open.... thoughts???
You just need to plug the 5/8 coarse holes at the rear of the head so you don't have a big exhaust leak.
You are talking about the bump on coming from the roof of the exhaust port? Unless your really dig into it, you shouldn't hit a water port. They can be ground smooth to the roof of the exhaust port without problem. As RegL404 says, plug the ports on the back of the heads and go. The thermactor bumps have holes in them. The air pump pumps fresh air through the piping into the back of the head so the unburnt gas will have enough oxygen to burn when it hits the catalytic converter. Your bud may have gotten a casting that didn't have holes in the bumps, I don't know how all of the castings were done.
Do you have the valves out of the heads? If you do you can go in through the valve side of ports and smooth the transition from the bowl or throat area(machined area under valves) to the rough port. It is usually a pretty good mismatch between the two. You would need to be extra careful not to nick the valve seats though or you would have to get them reground.
no i didnt take the valves out...i didnt want to take it all apart....i was just gonna do the hump grind.... i have heard that it is a good increase just from that....i need to get the heads put back on this weekend... the holes on the end of the heads are plugged... the one hole i was referring to a week ago....a plug of some sort with an allen head in the plug...i stripped it out trying to remove it.... i would be willing to bet, that is a plug that someone did because of the air pump being removed and to block off an exhaust leak...
sounds like it, which one? where is it? I'm itching to get started, but I can't tear anything else apart in the shop right now. Waiting on paint and the car is spread over a full bay... and the storage above the bathroom... and the 351 hanging from the hoist... The 351's exhaust manifolds are pretty big, makes me think about just trying to drop the 351 in there for a bit to see what its like... hehe
I have a set of these i started porting on and yes it has a big bump in it and can be ported out. The heads also have 58.2 COMBUSTION- CHAMBER VOLUME and 1.78/1.45 valves and where used in years 71-74 http://www.mustangii.net/head.asp If you remove the bump the exh ports are pretty huge
Plug the thermactor port with a length of dowel rod. I do this on later model E7 heads. Just get a length of rod and drive it into the port with a mallet.
Hello You sayed the same thing on one of my post but i didn't question it but i am not sure what you are talking about do you have any pics that will show me? THanks Jim
No pics, sorry. I just measure the inside diameter of the thermactor port (it varies depending on what year heads you have) then I buy a length of steel dowel rod that is the same size as the port. Simply hammer the rod in all the way through the head from one end to the other. Be sure you measure it to length before hammering it into the head. What this does, effectively, is eliminate the thermactor port in the roof of each runner. It also gives you some extra metal to grind into if you want to really raise the roof of the exhaust runner.
