8004-4-Z O-ring manifold conv. Nipple kit

Restoring an early Knucklehead requires attention to the smallest details, especially in the intake tract. This Colony O-ring manifold conversion nipple kit is designed specifically for 1936 to 1939 61 cubic inch OHV Big Twin models equipped with small-port heads. The kit features steel screw-in nipples with a zinc-plated finish for long-lasting durability. This conversion allows you to move away from older sealing methods toward a more reliable O-ring setup, which is a common upgrade for riders who want to spend more time on the road and less time chasing intake leaks. It is a precision-made kit that solves a common headache for early Knucklehead owners.