Bet you didn’t know!
The two electric wires extending from the main harness run vertically beside the intake or exhaust manifold to the horn, depending on the year.
Here is the way Chevrolet did it on trucks and cars: From 1938 and older trucks and cars the two horn wires run vertically up to the horn between the exhaust manifold and the intake manifold. When looking at the rear of the intake manifold mounted horn (on the early six cylinder) the two wire attaching posts are on a 4 o’clock position. This results in the two wires being close to the heat of the exhaust manifold. To better protect these wires from heat damage, the factory harness includes a 14 inch corrugated metal loom as part of their complete harness assembly. This metal loom was on all early Chevrolet inline six cylinder vehicles as well as on factory replacement harnesses.
Even with this loom protection, there was still occasional heat damage to the two wires! To solve the problem beginning in 1939, the vertical horn connecting wires changed position. Now, the wire was found on the exterior side of the intake manifold. The two connecting posts were rotated to be at the 8 o’clock position. This made it possible to keep the wires away from the manifold beyond heat. Thus, the protective metal loom was no longer necessary.
Surprise: The mechanical part of the 1934 to 1953 horn can be rotated by the hobbyist. Remove the six securing fasteners, on the perimeter rotate it to the new position, and retighten the securing nuts. Therefore, the horn is easily changed from the early to the later years design. This replacement loom is now available from Jim Carter Truck Parts and other full stocking dealers.
1934-36 horn. Connecting points at the 4 O’clock position
1937-38 horn with wires in metal vertical loom (beside exhaust)
1939 and newer on left. 1934-36 on right (connecting post on opposite sides)
1939 and newer. (Mounted on intake) 8 O’clock position. No metal loom required