Hacker Spacer Bolts For Electric Drives And Combustion Engines 10108407Hacker Spacer Bolts For Electric Drives And Combustion Engines 10108407 Adjustable spacer bolts made of turned aluminum to fit an electric motor or combustion engine into the R C model. The distance from the cowl to the back of the spinner as well as the side thrust and down thrust can be adjusted continuously by turning the thread. The distances from the motor frame to the rear edge of the motor frame can be continuously adjusted between 20 and 55