Universal stud made for fitting the HS4/HIF carb to the manifold (except
HS6 with alloy spacer on cast one piece manifold which requires
CHS2515 (5.8mm longer)) and it also fits the cylinder head to take the thermostat housing. Note that
HS2 carbs require larger CHS2613/4 studs, 5/16" unc with unf thread for nut.