I have an 85 F-250 with a 4.9/300 motor and purchased thermactor plugs from the Ford dealer (C6AZ-6052-A) only to find out that they do not fit my motor (90 to 94, swapped), only some older years. I need to plug the holes in the head for the air tubes/thermactor to get it back on the road ASAP. It previously had the tubes cut off, bent over and crimped closed, kind of tacky.

I need your thoughts on the following homemade plugs. I purchased WATTS plumbing parts, Brass Pipe Nipple (tube) 1/4" MIP x 1-1/2", and a Pipe Cap 1/4" FIP. I can place the cap on the pipe and it will screw into the head about 7/16" since that is where the tapered threads stop. I am concerned about the high heat melting the brass, but do not believe they are solid brass which melts at about 900 degrees celsius, and I believe the temp at the exhaust port should not get over 700 degrees celsius. In addition I am not sure about how strong the plug will be since it is tapered and will not have many threads actually holding it in place. My only other option is to purchase low-grade bolts and grind the threads off the last 1/2" and bevel the end like the factory plugs.

Your thoughts are greatly appreciated, and have a great 4th of July!

 

using the brass should work because i went thru motor since i bought off a guy that let it sit for quite a few years and i rebuilt the tube your talking about to get a new one was really expense at ford so i put new ends on all the down tubes and welded in new down tubes that where broke but i dont have any leaks or issues with it so far it been on there for about six months now


hope i gave you some help hope you gets things fixed and back on the road

 

Thanks for the input. I am not going to use my air tube and just need to plug the holes with something I can remove if I have to.