The engine in question is a Chevy 305 with a Qjet. It's in my '67 Jeep CJ.

The other day while we were winching it through a 200 foot mud hole, it started to run very rough. Since then, I did a number of things, including checking compression (it's even, from 110 to 120), checking the dist. cap, rotor, plug wires, etc, setting timing, and setting valves.

Strange as it may sound, it is running on only four cylinders. I can pull the other four plug wires with it running and the idle doesn't change at all. I then moved the plugs from the four dead cylinders to the four live ones. The other four cylinders died, while the former dead ones came to life.

Obviously this thing needs 8 new plugs. But I have never seen that many plugs quit at the same time. They are AC Delco R44T plugs. They were in the vehicle when I bought it, but don't look bad to look at them.

Does anyone care to venture an explanation? We did idle it a bit while winching, but mostly kept the revs up to keep the battery charged.

I would ventue to say that it ismt your plugs that are the problem but more so something with your ignition system....i would look at your distributer, wires, etc in a little more detail.....you also didnt say whether the plugs fouled all on one side or both sides that have fouled plugs. I would find it hard to beleive that it is a fuel problem but i would guess it is more electrical. If you want to see which cylinders are firing and which ones arent, get a squirt bottle with clean water, tart up your jeep and run it. while it is ideling, squirt a shot or two of water on each exhaust tube of each cylinder. You will be able to see which ones are firing and which ones arent by the rate of evaporation of eah squirt.

I'll bet that your fouled plugs are all in sequence of the firing order...one right after another.

good luck.

I'm betting the dead cylinders all trace back to a common intake manifold passage. Check for a mixture problem, but its more likely an accessory vacuum device like power brakes (master cylinder leaking brake fluid in) or PCV system.

BTW, a good way to clear fouled or flooded plugs if you are stuck in some remote spot is to run it at a fast idle and pull the coil wire out as far as you can without killing it. Usually about an inch of spark gap will do it, just position it there & run a few minutes.. Don't DRIVE it like that though.

i partly fouled out all eight of my plugs before i figured out i needed to rejet the carb.

Last night, I installed 8 new spark plugs. The engine sounds fine now!

The Q-jet has an automatic choke, which does not seem to open enough as the engine warms. I suppose that would cause the fuel mixture to be too rich, which could account for the fouling of plugs. Maybe its time for a manual choke!!