header modification idea

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Mar 2, 2011 | 08:42 PM

Onus

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Fleet Mechanic

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From: CT

header modification idea

So i really want to get headers for my 351w. The issue is that on the heavy duty f250s they inject air into every exhaust port on the exhaust manifold. Now of course no one makes a setup for this. Now what if i drilled a tapped holes into the headers made for a f150 or light duty f250. I say this as i do have emissions tests where i live and it has to pass to be registered.

Mar 2, 2011 | 09:04 PM

jimbbski

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From: Chicago area

I thought that on the 5.8L the A.I.R. system used an internal passage in the head to inject air into the exhaust. Check the back of each cylinder head, near the fire wall. There should be a hose running back there from the air pump to a fitting that then "T's" off with steel lines going to the back of each cylinder head. I have a 5.8L and this is how it's set up. It's the same on 5.0L as well.

I know that engines back in the 70's had passages cast or drilled in the cast iron exhaust maifolds for this purpose. I had a Capri with the 2.8L V6 that was set up that way. Later most manufacturers revised their head casting to incorporate the passage in the head.

Mar 2, 2011 | 09:29 PM

Conanski

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From: Ottawa, Ontario

For some reason Ford produced at least 3 different versions of this air injection system for these trucks. In 1/2 tons it was plumbed into the back of the heads.. and all the heads are riffle drilled right through front to back with plugs in the holes if that system isn't used. The 3/4 ton and heavier trucks got one of two variations on the theme with either a pipe attached to the back of the exhaust manifolds behind the motor or individual lines into the top of each manifold port near the head. Why there had to be 3 versions is beyond comprehension.. perhaps some engineer was justifying his existence, but in any case you could install any one of these and get the same functionality, and the system attached to the back of the heads would allow you to use early carb style headers with only the addition of an O2 sensor bung down at the passenger side collector and an EGR fitting on the front header tube. I did exactly this on my 5.8, worked great and passed sniffer tests.

Mar 2, 2011 | 09:33 PM

Onus

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Fleet Mechanic

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From: CT

What would be involved with a conversion to one of the other systems? Functionally these systems aren't any different correct? Seems stupid to make 3 different versions!

Mar 2, 2011 | 09:49 PM

Conanski

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From: Ottawa, Ontario

Simple, get the air pipe that goes across the back of the motor between the heads and attach it to the system in place the manifold feed tubing. The tube in question is clearly visible here. You will of course need to remove the plugs in the back of the heads.

Mar 2, 2011 | 10:02 PM

Onus

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Fleet Mechanic

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From: CT

Seems easy enough thanks a ton. I got to jack the motor up anyway to do the oil pan gasket and such. Now is their any special tubing need to go from the back of the head pipe to the air pump?

Mar 2, 2011 | 10:28 PM

Conanski

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From: Ottawa, Ontario

Yes... that tube isn't directly connected to the air pump there are a couple solenoid controlled pneumatic diverter valves in the system as well, but all you really need to do is detatch the tubing that currently runs to the manifold tubes and attach that to the crossover tube with whatever fittings you need to make it work. If you visit a junkyard you should be able to find a truck(van or pickup) with this system on it, and when you do grab whatever you need to make the conversion.