First off, as a new member, I'd like to say that this is a great forum.

I need a little help. its been a long time since Ive worked on any motor, let alone these newer ones with EFI.

I have a 1993 F250 with a 351W and 5 speed trans. the motor is a little tired with over 140,000 miles on it. Id like to replace it with a newer roller cam engine. Is this possible without major computer changes? Id also like to remove the air pump system. This truck has a GVWR of 8800 lbs and has the air tubes going into the ports on the exhaust maniflods. Ive had a lot of problems over the years with the tubes cracking and the check valves sticking. Id like to get rid of the whole mess but I am unsure how the engine will run if I do. Will the computer sense a rich condition and adjust or will I need a chip? I believe its a speed density system.

Sorry for the long post. Thanks in advance for any help.

 

>First off, as a new member, I'd like to say that this is a
>great forum.
>
>I need a little help. its been a long time since Ive worked
>on any motor, let alone these newer ones with EFI.
>
>I have a 1993 F250 with a 351W and 5 speed trans. the motor
>is a little tired with over 140,000 miles on it. Id like to
>replace it with a newer roller cam engine. Is this possible
>without major computer changes? Id also like to remove the
>air pump system. This truck has a GVWR of 8800 lbs and has
>the air tubes going into the ports on the exhaust maniflods.
>Ive had a lot of problems over the years with the tubes
>cracking and the check valves sticking. Id like to get rid
>of the whole mess but I am unsure how the engine will run if
>I do. Will the computer sense a rich condition and adjust or
>will I need a chip? I believe its a speed density system.
>
>Sorry for the long post. Thanks in advance for any help.

With ANY cam change speed density will suck wind. Trust me and a few others. Yes you can chip it for the cam, be if you ever want to add more to it, guess what...more money to be spent to reprogram that chip. I've never seen air pumping into the manifolds, just the heads. Depends on your local emissions if you can remove that stuff, I'd assume keep it there b/c it lowers NOX's

 

Maybe the air injection to the manifolds has to do with the weight rating. I used to have an E350 van with 351 and it had the same setup, copper tubes running along and above both heads individual tubes going to each port on the manifold. JBA sells headers with the same setup, but big$$$$. We dont have testing here at all so I wasnt worried about testing issues...only possible issues with the oxygen sensor and the computer.
Thanks

 

Well, as long as you don't move your O2 sensor around it should be okay w/o that airinjection into the manifolds. I moved mine once and the truck ran like crap, it needs to be appx centered on the Y-pipe by the pre cat.