About those insulating spacers…

November 1, 2018 | By Staff


I recently acquired a 1947 Cadillac Series 62 that had been stored in my neighbor’s garage for many years. It is pretty complete, but has been partially dismantled. One thing that is missing is the spacer that goes between its two-barrel carburetor and the intake manifold. I have looked everywhere for this piece and have not had any luck finding one. What are they made out of, and where can I get one?


That spacer is primarily an insulator, and for some reason many people who don’t understand the need for these items have discarded them over the years. Classic flathead cast iron engines produce a lot of heat, and that heat is transferred to the intake manifold and up to the carburetor if there is no insulating barrier to stop it. On a hot day this leads to vapor lock in the carburetor.

What happens is the fuel in the float bowl boils and vaporizes, and the engine doesn’t get any fuel as a result. Vapor lock can also occur when the fuel lines get too hot, and when the fuel pump overheats as well. The short-term fix in the old days was to wrap wet rags around the offending device to cool it; but the long-term solution is to insulate the fuel system from heat.

Fuel lines can be wrapped with the same woven black cloth insulation as was used for wiring years ago, and in addition, fuel pumps often have metal shields to protect them from the heat, as well as a protective insulating gasket.

Those carb spacer blocks were made of Bakelite, but these days it is more commonly referred to as phenolic resin. The stuff can be purchased in sheets from plastic suppliers, but the catch is, you will likely have to buy a piece of the stuff several feet square in order to get that two-inch by four-inch block you need for your insulator.

Phenolic insulators are commonly available at speed shops for later fourbarrel carburetors, but almost impossible to find for two-barrels.

However, the good news is you can make a replacement out of hardwood that will insulate even better than the phenolic material or you can make one out of aluminum that, while it won’t insulate as well as the wood or the Bakelite, will do the job.

If you decide to make one out of wood, use ½-inch thick hard, dense oak, ash, or other hardwood, and after you complete it, soak it in motor oil overnight before installing it. This is oldschool, but it is very effective and long lasting. Or, if you can find ½ inch thick aluminum you can machine a spacer out of that.