The Stovebolt Site Forums The Shop Area Engine Shop Distributor hold down....

Jerry was explaining the slotted hole. There is an image below...it doesn't show everything in clarity, though. You'll have two methods of adjusting timing, actually. One: your distributor will be held by a squeeze clamp which is part of the retaining piece. Unlike the distributor for say a 283 V8 there is no molded stop ring to make certain it only goes in so far. Before you adjust timing and tighten this, please pull up the distributor a wee bit (maybe 1/16") to get the tang just off of the oil pump piece. This clamp allows you to initially loosen and rotate the distributor to establish proper position relative to top dead center and flywheel, etc. And two: there is an engraved line in the center (which should reflect where proper timing for your engine is) and there are engraved lines above and below that line which correspond to advanced or retarded timing (a person could have chosen them to use with higher or lower octane gasoline). Once your timing is set properly using the squeeze clamp, you can adjust + or - your timing by loosening the hold-down bolt and rotating the distributor and that piece (which also incorporates the vacuum advance canister and linkage). Hope this helps.