Hi.....my 235 engine has an octane selector on the vacuum advance.
My question is this.............when tightening down the "distributor " are you supposed to do so by tightening down the bolt on the octane selector, or by the slotted screw at the base of the distributor ?????? THANKS, J

1953 chevy 1/2 ton with 3 speed 318 on floor and 1955 235 engine