Originally Posted by lance-burton
I have a 1930 Model A, the 4 cylinder engine has been modified by adding a mild cam, balanceing the rotating assy, lightling the flywheel, over size intake valves, electronic ignition and I am adding a Stromberg 97. Does a two inch riser do anything to help my engine or will it effect the preformance? Presently on a Dyno I have 60 hp at the rear wheel with 147 lbs. of torque at 3000 rpm, and a stock rear end.
Adding a 2-hole spacer will add length to the intake runners and this tends to help boost low end torque.
Adding an open spacer tends to add plenum volume as well as connect both sides of the intake to both barrels of the carb. Generally speaking, this can help the mid/upper range at the expense of the bottom end.
That said, there's no way to know exactly what will be the result until you try it/them. Some engines have been known to behave 180 degrees to what they're "supposed to". But if it was me and I could only use one type spacer, I'd try a 2-hole spacer instead of an open one.