Bad timing is never fun, please help!

hello, i am having an issue setting timing on my 65Lemans with a 455. this concerns a pertronics hei unit. while setting initial timing (at 18*), i will pull the rpms up to get my mechanical advance reading. at about 1800rpm it gains about 12* and at about 2000 my timing light goes nuts. while looking at the balancer you will see a reading of 18, 50, 45, 2 and so on. its all over the scale. the engine seems flat and as an irritating random but constant misfire. i have had this issue for a while and can't seem to find it. i have replaced plugs, wires, cap, rotor, tested the coil and pick up, checked for vacuum leaks, did a compression check, i even put air in my tires to no avail. this doesn't seem to be a basic issue. is there anyone one here with some knowledge about these distributors got any ideas?

p.s. i am having this issue on every plug wire, i set timing using my #6 wire and just clipped my light to other wires to see if the lights pulse was rythmic. it wasn't. ever wire has this miss.  

sounds like the issue is the module and/or pick-up assembly. not sure what kind of set up this distributor is but the pick-up and module is what controls the spark. make sure it all grounded good too.  

i agree...    take a look at the pick up coil assembly...  is the magnet cracked????   there are several layers of parts held down by the retaining screws....

you might just try a whole new pick up coil..

you do have to pull the distributer and then the shaft to get it off..   be sure to knock any burs off the shaft when you take the gear off...   then turn the housing upside down.. and fill it with carb spray or brake cleaner... while working the shaft in and out while turning... you may have to spray it several times.. as you work the shaft farther and farther out.. until it clears the upper bushing and comes out..



this happens on later model small cap HEI's with the remote coil.. but the magnet that is mounted on the shaft under the reluctor wheel cracks...

instead of a nice smooth  AC wave ,.. it gets random and ghost waves...  the module is expecting a nice clean AC wave...  when the signal goes above 0.3 volts RMS... it connects the coil to ground to charge the primary...  as the signal starts to drop.. just before the signal voltage reaches 0... the power transistor opens.. discharging the coil... as the tips of the reluctor and pick up coil move apart the signal goes into negative voltage... until the tips start getting closer again..


with an HEI...   you can actually set the harmonic damper timing mark. to the base timing...   turn the distributer housing until the tips of the pick up coil and reluctor line up exactly... and lock the distributer housing down..   when you turn the key...  the engine will start... without you having to turn the distributer housing..

two last things... pull the coil cover off the top of the cap... look in at the wiring from the coil.... see that there is a flat bent piece of metal that comes out from under the coil corner and connects to the center wire up from the distributer base..  this is the ground return for the ignition coil... without this .. the HEI will do strange things..   like make noises...  sort of sounds like a shot gun going off under the hood...  yes.. that loud..