Special thanks to John Quinn For sharing this with the group.

The picture below shows the upper openings of the heat riser tubes cast into every Ford flathead V8. The one at the top of the pic is open, the one on the bottom has had a penny driven into it sealing it off. The bottom of the tubes open into the middle exhaust port. Hot exhaust gas rises up the tube and matching holes in the intake manifold heat the area of the manifold under the carb causing it to warm up quickly after start up on a cold morning. Some old timers started blocking the tubes with pennies to make the carb cooler in hot weather and discovered that the exhaust note was made crisper in the process. Just one of the many examples of homemade modifications started years ago on these historic engines that are now part of flathead lore. Other examples are clothespins on the fuel line or mashing half a grapefruit over the top of the fuel pump to cure vapor lock on a hot day. There’s no telling how many wonderful “cures” for flathead problems have been lost to history as the old timers pass on.

Modern pennies are slightly larger diameter and have a harder alloy that doesn’t work as well as the pre 1959 wheat backs.

Quote from another member: “My Dad also said they need to be the wheat penny. Newer pennies are just a tad smaller and wont stay in. He also said with those pennies inserted in heat risers his high school hot rodded 36 would really “pop”.”

The point of this trick: Also unless your living in a very cold climate exhaust heating the intake isn’t really a must. This trick helps keep the carb cooler and makes the exhaust note sound better. This was confirmed by a number of our members.

Special thanks to John Quinn For sharing this with the group.