Ford 289 Thermactor Plugs

Posted by John Roth on 27th Dec 2020

I have a 289 in a Willys Overland Pickup Truck. The previous plugs were brass hex head plugs that protruded into the manifold gasket and one actually developed a small hole in it, hence an exhaust leak and loud popping sound. The previous gasket was thick, so that helped, but still, the plugs interfered.These plugs, after installed, were recessed, and worked perfectly. the allen heads made the installation much easier. Getting the old ones out intact was the real challenge, it took a couple hours using a socket with a straight edge blade inserted into it (passenger side rear was angled to rear so some extra patience and trying different approaches). In the end it all worked out great and hopefully will never have to re-visit. Thank You!!