Ive got a '57 Plymouth with the flathead 6 and the 2 rear cylinder arent firing. Anyone have any idea why not? Its got me scratching my head. I can't see anything out of the norm. Thank you for any help provided.
If by 'not firing' you mean no spark to the rear 2 spark plugs, then the distributor cap and/or spark plug wires, or spark plugs themselves are the items to check thoroughly. If the plugs ARE firing but the cylinders are not producing any power, first thing to do is check compression.....on all cylinders, but most especially on those two. Low compression can be very worn pistons and rings, valves 'burned' or not seating. The latter might be corrected by adjusting valve lash. Your Plymouth has solid lifters and require periodic adjustment. Ray
Yup, not firing. I'll be checking it out further in the morning but it threw me the fact that it seemed random, 2 at once. Thanks Ray
another thought, it is possible you have a vacuum leak in or at the intake manifold/block junction. That could take out both those cylinders as they are fed by the same manifold branch. Edit: if compression on those two cylinders is very low, it is also possible you have a 'blown' head gasket between cylinders 5 & 6. Ray
FlatHEAD six, flatHEAD six. If the rest are firing it may be bad plug wires or bad plugs. Resistance wires should have 5000 ohms per foot, if resistance is infinite you have a bad plug wire. If the wires are ok try a plug you know is good. But, the fact that it is 2 adjacent cylinders make me suspect you mixed up the plug wires.
Not really much it can be plugs, wires, cap or rotor If your just not getting spark to those cylinders. Start with the easy stuff first, check the wires aren't mixed up and that their still good. If they are you'll know it's probably plugs.
How about checking the bushes on the dissy shaft for wear, or maybe a couple of cam lobes are worn on the dist shaft.. Is the wire to the points/condenser being hit by the rotor as it turns, causing it to miss??
The Jalopy Journal
