So been a member on the forum for a few days now and have been doing lots of research about various things. And today I was about half way through removing the smog system (not interested in any debates whether or not it should be removed) when I realized my setup is a little bit different then what most others have explained on this site. Most people have pipes running to the catalytic convertor and have a crossover tube between the two heads, both of which must be capped when doing the project. I however have neither of those on my truck. What I have, is a crossover tube between the two exhaust manifolds and the spot on the catalytic convertor where the tube would go is welded shut. Below is a picture of one side, other side I couldn't get my phone to focus, but same idea and there is a large pipe probably 3/4" or so connecting the two manifolds, directly behind the intake manifold is a junction where the crossover pipe meets the pipe from the valve up on top of the engine. I assume they must also be capped with the removal of the smog system. Has anyone seen this before and more importantly does anyone know the size of the cap or plug I'm going to need to cap these. Also on my truck I am missing either the tab or tad solenoid, not sure which is which, but I only have one of them and in the other spot is just a electrical connector that I can tell has never been used.

Another difference I have noticed is most people referring to the cap off of the pipe to the catalytic convertor, refer to "cats", am I to understand that meaning more than one, as I only have one, it is a big one, but I only have one.

I'm assuming my truck is different because its a 1995 chassis cab f350 5.8l with a gvwr of 11,000lbs. Most everyone who's threads I have been reading were being completed on 1/2 and 3/4 ton trucks.

Thanks for any pointers!

 

sorry about the hose in the way, but I was trying to show everyone that there is no second solenoid in that location

 

So after I took the last pictures, I had decided to call it a night, but after having a few beers, I decided not to call it a night, lol. Attached is the pipes I got from the truck, I had originally thought it was one pipe that crossed over and had like a Tee fitting welded in it, but it turned out to be 2 pipes, each manifold had its own and the split was at the back of the intake via a rubber hose Y adapter. Man what a royal PITA to get out. Accidentally broke the 90 degree fitting coming out of the valve cover going to the pcv valve, but I did get it out. not all in one piece, I just put back together to show you what my truck had in place. Blocking off the holes in the manifolds will be easy, either going to weld up the little adapters I already have or I may go to the hydraulic shop up the road and see what they have in the AM.

Also took a better picture of where that second valve normally is, my truck is definitely a bit different, The air from the smog pump either went to the manifolds or the muffler up top.

Once I had them out I tested the check valves by blowing in the pipes, one valve was good (drivers side I believe), but the other let air both ways, I'm thinking this may have been the cause of another problem the truck has had recently which was when sitting in a parking lot or a red light with the truck running, the cab was very fumey, I thought I had an exhaust leak, but maybe this valve was letting exhaust go the opposite direction and dumping it on top of the motor out the little muffler up top. I don't know for sure, but I'm glad to have all of this stuff off the truck.

 

Yes the HD trucks(8500lb+ GVWR) have a different air injection system although it's function is the same. Instead of separate TAB and TAD solenoids there is a single and it must remain electrically connected but you want the vacuum line capped. Those holes in the manifolds must be sealed up air tight so pipe fittings are the best solution.

 

did it run smoothly before you took everything off? im intrested in doing this with my '93 4.9

 

Truck is new to me, bought last Saturday. Let me put it this way, truck ran smooth enough to cruise 400+ miles back home doing about 75mph, with only 2 issues (1st it ran out of gas, gas gauge not working and 2nd upper radiator hose blew) But truck has it's little issues. including a slight miss at idle, and having to hold gas pedal to the floor to get it to start.

From what I've read and understood from other ford owners is that the system neither helps or hurts the engine in any way. It's just a matter of preference, I mostly did it to eliminate clutter under the hood. (I literally have a pile of parts sitting in my driveway).

I'm fixing several issues at the same time, including a new vacuum lines, pcv valve getting changed, new plenum gasket, possibly new spark plug wires (at least going to rerun them as currently they are all zip tied together, which may be causing the slight miss, I'm experiencing)

 

OK, so got it all back together except for plugging the exhaust manifolds, I was unable to find a plug with the same threads as i needed, so going to have to get it welded closed. But other than that it's all buttoned up. Didn't end up with new wires, as I haven't decided which ones to go with. Truck is still missing slightly when idling, but I no longer have to mash the gas to get her to start. I'm going to contribute that to either a vacuum leak or a clogged pcv valve. for the record I used a K060962 gates belt for the bypass. It fit perfect.

 

do u have a picture of the engine bay now?