| : I have so much wear in my distributor shaft I can not time the engine by the book (the rotor will move about 3/4 " back & forth ) what should I replace? upper & lower shaft,drive gear, bushing, cam or all the above.|
Three-fourths inch (3/4") is a bit much movement. Try first removing front valve cover to see if you have part A6275, camshaft thrust plunger and spring, ($3.20/set), which restricts back & forth camshaft movement -- some guys forget to reinstall this item, and sometimes spring gets stuck in engine goo -- also maybe get part A6020, front timing cover gasket, ($00.60).If after installing this plunger/spring item the problem is corrected, you may want to stop here;or, if your rotor moves back and forth more than 3/16" on the shaft, try getting a new rotor for $2.40 & maybe get a distributor lower shaft for $2.80 = $9.00 so far.
Just depends how for you want to go!
Most A's have rotor backlash, but to overcome this looseness, with points adjusted & with spark retarded and timing pin in place, turn cam counter-clockwise until points open wide, (when rotor is at No. 1 contact point in distributor head);next, turn cam clockwise until points just close -- then lock cam with screw.
Always re-check the setting after tightening screw because cam sometimes slips.Let us know what happens!
Best wishes, Henry