Volvo Owners Club Forum - View Single Post - Volvo 164 B30A Double Butterfly Inlet Manifold

volvo_saint · May 16th, 2020, 23:00

I am doing a rolling road restoration on a 1973 Volvo 164 B30A Automatic.

Last summer the cylinder head was off for a clean up and I noticed that there is a second set of Butterfly directly in the inlet manifold. They are directly actuated from the Strombergs.

The first set is the actual Stromberg 175 carburettor itself and the 2nd set is in the inlet manifold.

This set me thinking that in order to balance the Strombergs Carbs you need to deal with two sets of butterfly for each carburettor.

Does anyone know why Volvo used this double butterfly set up on the B30A ?

Is the 2nd set of Butterfly valves actually necessary ?

Or can they be removed ?

May 16th, 2020, 23:00	#1
volvo_saint Junior Member Last Online: Jul 8th, 2023 14:27 Join Date: Feb 2007 Location: LIJA	Volvo 164 B30A Double Butterfly Inlet Manifold I am doing a rolling road restoration on a 1973 Volvo 164 B30A Automatic. Last summer the cylinder head was off for a clean up and I noticed that there is a second set of Butterfly directly in the inlet manifold. They are directly actuated from the Strombergs. The first set is the actual Stromberg 175 carburettor itself and the 2nd set is in the inlet manifold. This set me thinking that in order to balance the Strombergs Carbs you need to deal with two sets of butterfly for each carburettor. Does anyone know why Volvo used this double butterfly set up on the B30A ? Is the 2nd set of Butterfly valves actually necessary ? Or can they be removed ? __________________ P1800S 1967 - Volvo 240 Estate 1986 - Everyday car...Volvo 164 1968 - Volvo 144 1967 - Volvo 144 1973 model - needs rust repair..and Volvo 164 1973.