You have to have some Clearance between the Idle setting and the Round stem coming down ( Not sure what you call it LOL ) but you need about at least 15 Thousands Clearance before you can really set the Air Mixture properly > is one on each Carb
*** Not sure if a 70 still has them but >>
If you have Heat risers still makes is Hard to set those Carbs > the Risers Shafts leak exhaust most of the time anyway and smell make noise > Remove the shaft and tap then Plug the manifold > You need to Make a Little Block off Plate to go between the Manifolds
or it will get to hot under the intake and over vaporize Fuel
hard part is to remove the bolts the connect the manifolds together >

They run great blocked off