Join Our Ford Truck Forum Today

Document your Ford truck project here and inspire others! Login/Register to view the site with fewer ads.

1994 F150 w/ GT40 heads Smog Equip Question

O'Rattlecan

Redneck Prognosticator
26,689
797
Belton, MO
So I have a question. I don't even know what this equipment is called, and this is the closest thing I could find on the internet regarding my problem:

http://www.allfordmustangs.com/forums/5-0l-tech/209645-gt40-not-p-head-smog-issue.html

So here is the piece in question (top left, bar attached to the head and extending toward the other head which is not visible):

IMG_1770_modified_zps0512936f.jpg


On the back of the OLD heads, this is where/how it attached.

20140302_173018_zps3e916844.jpg


On the new heads, I'm missing the holes.

20140302_172337_zps95702f61.jpg


Since the holes do not exist on these heads, I'm thinking less about 'doing it right' and wondering if I can somehow bypass or remove this equipment without damaging the engine.

Can someone who knows what they are talking about shed some light on what this piece on the vacuum system does, and if I can go without it?

Ryan
 
Last edited:

O'Rattlecan

Redneck Prognosticator
26,689
797
Belton, MO
Doing more research, it looks like this system blows air into the head on cold starts, but then redirects air to the cat converter when warm. maybe I can redirect both tubes to the cat at all times.

Ryan
 

blacksnapon

Moderator
Staff member
What that does, is injects air into the exhaust ports. If you look at the old heads you'll see a small "bump" in each one with a hole in it. The extra air helps to burn off any remaining hydrocarbons in the exhaust flow. If you can run both hoses to the exhaust, that would somewhat simulate what its supposed to do. Excess hydrocarbons shorten catalytic converter life.
 

O'Rattlecan

Redneck Prognosticator
26,689
797
Belton, MO
So Vince, in your opinion, would rerouting both pipes to the exhaust behave acceptably with my computer? I was thinking that I should keep most of the equipment on the truck, even if it's not in its original location.

Ryan
 

blacksnapon

Moderator
Staff member
The original intent was to have the air injected as close to the exhaust valve as possible, so it would be trial and error to get the o2 sensors to read correctly at a given rpm/load. The piece mounted on that pipe from one head to another is the diverter valve. One path to the exhaust valves, the other path downstream.
 
Last edited:

O'Rattlecan

Redneck Prognosticator
26,689
797
Belton, MO
I think since those holes are no longer available, my best option is to send both valve outputs further downstream into the exhaust. It won't mix as well but I think the only downstream oxygen sensor is the HEGO sensor (right before the exhaust pipes join into a single pipe.

Ryan
 
So I have a question. I don't even know what this equipment is called, and this is the closest thing I could find on the internet regarding my problem:

http://www.allfordmustangs.com/forums/5-0l-tech/209645-gt40-not-p-head-smog-issue.html

So here is the piece in question (top left, bar attached to the head and extending toward the other head which is not visible):

IMG_1770_modified_zps0512936f.jpg


On the back of the OLD heads, this is where/how it attached.

20140302_173018_zps3e916844.jpg


On the new heads, I'm missing the holes.

20140302_172337_zps95702f61.jpg


Since the holes do not exist on these heads, I'm thinking less about 'doing it right' and wondering if I can somehow bypass or remove this equipment without damaging the engine.

Can someone who knows what they are talking about shed some light on what this piece on the vacuum system does, and if I can go without it?

Ryan



Hello and good morning Ryan.

By all means go with the GT40 Heads as they are sweet and boost performance. If you have the money buy some "tuned" headers and have the Heads Ported and Polished to match the Headers Exactly.

Tuned Headers are the very best as ALL TUBES ARE EXACTLY THE SAME LENGTH which will give you the "most bang for the buck."

The cross tubing pumps air into the heads from the smog/air pump and just purchase some 5/8" X 11NC X 1" Grade 8 Bolts(Napa) and some COPPER CRUSH WASHERS(Summit Racing) for a good seal.

Caution: The bolts cannot be longer than 1" and you also have to cap the smog/air pump pipe/outlet.

Most just pick up an Idler Pulley from a car at the boneyard and disconnect all of the plumbing and remove the pump. You can also purchase a shorter Serpentine Belt but then you are straining the Alternator Bearing. If you want to go with the shorter belt then use a piece of string for the measurement.

You will have to trace all of the Vacuum Lines and cap them at the source. I recently replaced all of the plastic vacuum lines with rubber hose as those darn stock vacuum become brittle in a short period of time and also where you live has something to do with it: expansion and contraction.

Boon

Postscript: Of most importance is your location and if a Smog Test is required.

I do not know what I am doing I just pass the information along that was given to me, nothing more.
 
Top