Injector is a misnomer, it's just a normal gasser Tillotson with a different way to choke it...I had forgotten about these engines..About 4.2 cubic inches...Some were converted to methanol to use as race engines in our USRA racing series...Last one I saw was in Glendale, AZ on Mike Hatfield's Formula One plane at a race promoted by Dave Bridi and Leslie Burnett...It was a real shaker and was not successful...The carb can be rotated by using a pressure fitting in the case and another in the back cover of the carb...Nothing wrong with it the way it is, just be aware of the way the choke works...Some of the carbs had a small screw holding the rotator mechanism in, some were just pressed in..A SDC80 will work fine, no difference in the way it performs or where the pulse hole is, you won't gain anything by changing it....The cylinder and piston are probably a 4.4 Husqvarna, 72 ccs...If anyone wants another I know where a lower end is minus the cylinder and piston.....Don't know what the price is, there are a few NIB gasoline versions available, last price I heard was about $800....