Expert: Kevin Pilotte - 11/1/2006

Question
Hello,
I have a 79 cj5 with an amc 360 and motorcraft distributor. that intermittently misfires particularly at cruising speed.  It idles great, but bucks under acceleration and cruise (about 2600  rpm).  I found that that the pickup coil had freedom to move up and down.  I replaced the pickup coil, which also had freedom to move up and down (even with the retaining clip), so I ultimately replaced the distributor. When I bought the new motorcraft distributor, I didn't notice any freedom for the pickup to move up/down, nor did I notice any significant misfires. Meanwhile, my misfires have returned.  Now there is a slight bit of play for the distributor to move up, but not to the touch.  It looks like the reluctor has not been hitting the pickup.  Is a slight amount of vertical play (and I mean very slight) normal for the pickup coil, or does it need to be rigid against the base plate?  Given that it is not burned and that a slight amount of play is alright for the pickup coil, do you have any other suggestions (fuel pump and filter are new, plugs are gapped correctly and not fouled, and it idles good)?

Thanks,
Jim  

Answer
Jim,
I wouldn't worry about the little vertical free play inside your distributor.
Two items that could cause your condition are plug wires and ignition coil. They often break down under load. i.e. acceleration.
You could measure the resistance of the wires and the ignition coil, but if they are a few years old I'd say replace them.
Kevin