In the early 1960s, Ford had seen the ascent of the Chrysler Hemis in the racing world and was eager to level the playing field, perhaps tilting it in their favor. They put their collective noses to the grindstone and delivered one of the most aggressive engines of the era with the FE-based 427 Cammer. It was strong enough to bring home NASCAR's manufacturer's title for 1964, but was subsequently banned from competition in 1965. There was a good amount of backroom brawling about the Hemi and the Cammer, and in the end, NASCAR pretty much said the SOHC engine was too high tech and was never offered in an actual production vehicle, so they effectively banned it. Not willing to take the hit lying down, Ford fought back with a vengeance. In 1969, after carefully reading the NASCAR and NHRA rulebooks, they came up with an engine design that smacked the rest of the racing world square on the nose. The Boss 429 "Shotgun" engine was born.

Per homologation rules of the time, a minimum of 500 of these unique engines were required to be installed in regular passenger cars in order to be legal for the races as well. Ford contracted with Kar Kraft to install these redesigned "semi-hemi" 385-series engines into specially ordered '69 and '70 Mustangs, Cougars, and even some Cyclones. Unfortunately, the pencil pushers killed the budding Boss program in '71, leaving those wanting to race the hemis high and dry once dealerships started running out of replacement parts. Setting out to help solve this problem, longtime Ford fans Todd Miller, Doug Everstine, and Eric Simone recently competed in the 2009 Popular Hot Rodding Engine Masters Challenge to showcase their brand new TM Enterprises Boss Hemi heads sold on their ShotgunHemiParts website.

To say they were "showcasing" their heads is probably an understatement. With over 850 horses on tap, their 534-cube Boss destroyed most of the field, easily landing the team in the top half of their very first EMC trial. Team leader Simone was obviously pleased, and credited cylinder head designer and team member Miller with creating an incredible cylinder head as their jumping off point. A mold and pattern maker by trade, Miller had no problem creating a casting that was as visually stunning as the original, and had the advantages of modern casting techniques and materials.

The heads externally look the same as the factory Boss castings, but without the Ford logo or part numbers to avoid any trademark issues. They also accept all of the OEM parts and accessories such as rockers, valves, and valve covers. To update the heads, Miller's design eliminated the use of the O-rings to seal the combustion chambers. Simone discussed some benefits of the new TM castings: "They use a modern gasket that we modify and sell as a complement to the cylinder heads. We eliminated the copper ring dry deck thing because the original heads had two problems. One, Ford did not reinforce the head bolt columns well enough. They didn't put enough material there and they back up right against a water passage. The torque on the OEM cylinder heads is only 90 to 100 lb-ft, that's it. Most people see that big 9/16-inch bolt and they immediately want to torque them like a 460 to 140 lb-ft. The problem there is you crack the head or you bend the head." The second weakness that TM Enterprises addressed was the material itself. "The aluminum that Ford used was high-quality aluminum for the day. The problem was the heat treat process. There's probably not a set of original heads out there that isn't bent in some fashion."