I have a newly aquired 56 F250 with a 272, which was running when I bought it 2 weeks ago.

First job I did was to replace dizzy cap, plugs, plug wires and install a Pertronix electronic ignition module with Flame thrower coil.

The motor starts readily but feels rough from insde the cab but smooth from the engine bay. Now heres the thing;

I can remove 4 plug wires and the engine idles with no change at all. If I remove any of the others it runs rough. Its as though its only firing on 2,3,5 & 8 and therefore only missing everyother cylinder - BUT every wire has a good spark.

I double checked all the wires and the dizzy cab, everthing is in the correct firing order. I checked TDC with 10 degrees advance and eveything lines up. I pulled the plugs and can see unburnt gas on those cylinders where I can remove the wires and have no change to idle.

I put shop towls in the plug holes of the 'non firing' cylinders and they pop out with a pop, so imagine I have good compression.

Any thoughts out there? Could it be a miss-alined timing chain or maybe the ignition is off, it has a 57 model year distributer. Should I put the points back in and see if that solves anything?

Any help would be much appreciated.

Oh the exhaust note does not have that typical Y block burble, I guess 'cos its only a four banger????