No smog tube holes on the GT40 Iron heads?

[StreetDreamsGT]

Hey guys, I went to hook up the smog tube to the back of my GT40 Iron heads, and it looks like there aren't any holes drilled for it, upon taking a look at my speed density heads then feeling around on the back of my GT40's I can definitely say they're aren't any holes there. Do the heads use a different type of tube or are they just not setup for it? I'd heard it was only the GT40 p's that weren't setup for it, not the plain 40 Irons. If I don't hook it up what will it effect? I'm just worried about not hooking everything up because I don't want to mess up the vacuum solenoids or anything and throw off the computer.
Thanks

 

[StreetDreamsGT]

Well I did some reading up and found this in one of the other threads.

"The cats aren't hot enough during initial warm up to help as they don't light off - that's why the air pump output is shifted to the heads on cold starts - so the cold air from it doesn't slow down cat warm up and light off. What helped control emissions to lower levels immensely during cold start up was heated O2 sensors. Instead of the 90-120 seconds needed to get the non-heated ones to operating temp (they have to get to 570F before they generate a stable signal), the heated O2's can be ready to go in 15-30 seconds, allowing the car to go into closed loop MUCH sooner on cold starts. Not only improved drivability, but allowed for better mixture control when cold - until the cats get hot enough to help. Air pump output gets switched to the cats once they're hot enough to light off."

So that being true it seems the only thing not having the tube causes is to have the air diverted out into the atmosphere.

 

[rd]

I have two sets of iron GT40's and they have air injection passages. On my 79, they are connected and the pump is in place. On my 82, I have the holes plugged.

Is it possible that yours were already plugged?

 

[BlownFiveLiter]

Are you sure they're standard GT40s not the GT40Ps? The P heads don't have the provision for smog passages and would need them drilled by a machine shop if you wanted to retain them.

 

[innes]

It’s because you got your GT40 heads from a 96 and up truck (explorer) they don’t have that. If you got them of a cobra or a lighting they would and same for the "P" heads.

 

[DucatiRdr]

I have a set of Mountaineer heads from an early 97. They are GT40 non P and don't have the thermactor provision.

Are you going to get those heads shaved? I read somewhere that the explorer heads were not chaved where the Cobra heads were.

What are you going to do about the head smog tubes? Are you going to (can you) get the heads drilled and tapped for the thermactor system? Can you just leave these hanging there?

 

[StreetDreamsGT]

I got my heads off a 96 Explorer, so that must be why they're not there, honestly as long as what I read in the other post holds true, i'm not even going to bother with the tube. I should probably check with one of the more knowledgable guys on the board here, but if no one answers then i'm just not going to bother with it.
Ducati, what do you mean shaved? I already have them mounted on the block and everything so i'm not going to bother, but I'm curious what you're talking about.

 

[v8only]

you guys are correct, the explorer g40 heads have no thermactor holes.

don't bother drilling them out, it won't effect your smog test. Smog test is taken warm, by that time the air diverts to the cats, since you don't smog cold, no reason to have it going into the heads. been there, done that, passed cali smog.

 

[DucatiRdr]

what do you mean shaved? I already have them mounted on the block and everything so i'm not going to bother, but I'm curious what you're talking about.

Dunno exactly. I did some online research before buying my Explorer GT40 heads and read that the Explorer heads have a different combustion chamber size compared to the OEM Cobra GT40 heads. I was recommended to have the combustion chambers resized to 60cc or so. Maybe someone more in the know could fill in where I left off.

 

[StreetDreamsGT]

The other thing I found is the aftermarket headers I got don't fit the heads, they fit on my 87 block just fine but not this one with the gt40's. The stock header manifolds fit though.

 

[DucatiRdr]

The other thing I found is the aftermarket headers I got don't fit the heads, they fit on my 87 block just fine but not this one with the gt40's. The stock header manifolds fit though.

Really...I thought the GT40 and e7 heads had the same exhaust port layout. Who makes the set of headers that didn't fit? How didn't they fit - port position or...?

 

[v8only]

that's actually incorrect, perhaps you should check if you've got gt40p heads, not gt40 heads. If you do, it'lll say gtp on the side (see my sig pic) and it will have 4 bars on the front. Gt40's will have three bars on the front and GT on the side.

If you have a set of gt40 heads, all aftermarket headers will work just fine. If you have the p heads, you'll need some frpp headers to fit, or mac.

 

[rd]

I forgot that some Explorers had Gt40's, before p's came out.

I have one set of iron Gt40's that came new in SVO boxes, and one set from a 94 Lightning, both have Thermactor holes. Both bolt up to headers that fit standard old Ford heads, D80E's in my case.

The header fit would seem to say you have Gt40p's.

 

[StreetDreamsGT]

nope, I bought a 96 explorer long block, and before I paid I checked and it had 3 bars and said gt on the heads, it was the position of the bolt holes that didn't line up, not the exahust ports, I bought em off ebay, I don't even remember what brand they were.

 

[v8only]

you got jacked on the headers then, they're not 5.0 headers cause you're the only person who's ever had a bolt hole fitment issue with gt40 heads. Hell, even the bolt holes on the p's are the same, it's the spark plug angles that are diff.

 

[StreetDreamsGT]

yea I figured it was something like that, shyt happens

 

[v8only]

look at it this way, you've got a great block/set of heads, and just need some headers (or could re use the stockers for now)

post up the headers in a new thread, look for a part #, find out what they are, and sell them on ebay for what they really are.