How do I plug the smog ports from the air tube in the head

[96999153E4OD]

Hello all, I've got a 1996 F150 with the 4.9L six, and the air/thermactor tube that goes into the head is making a loud noise, and I want to get rid of it. I'm in Arkansas, so no emissions testing, and the cat was removed by the previous owner. I was wondering what size bolts I need to plug the ports in the head. Will straight thread bolts work, or do I need taper threaded fittings? Oh, and if anyone has done this before, please chime in on how you did it, and how it worked out. Some pictures would be great. Thank you very much in advance.

[Prof2113]

I have the same truck and engine. I have emissions testing here, so not doing this for another 9 years, but this is what I would do.

1. Find fittings in brass or steel that are the same thread if possible. Haven't looked, so not sure if you could find them at the local hardware store.

2. Remove the assembly and cut the smaller tubes off at the main tube. Then crimp and fold the tubes over and then weld or braise them shut. Then screw them back in the head.

Since I have replaced my tube already, a few tips.....

You really want to use a line wrench for this job. The fittings are thin and will flex when loosening. If you use a line wrench, it helps combat that problem as well as rounding off the fittings. I sprayed copious amounts of wd40 on the fittings before removing and let them set over night. They came out without a problem.

If you are going with option 2 and you destroy a fitting, they are available as a set from pciinc.com at a reasonable price. I got the tube and all fittings for about $100. I think the fittings as a set are about $40.

Good luck and let me know how it goes.