2.25 not firing 3&4 ?

[Lance]

Just tried both of your suggestions. It will run on different combos of wire configurations even on one cylinder. Connected coil so it was off the harness straight to the battery, switch off. No change???
Seems to run on any two cylinders, doesn't matter which two but only two??

[Apis Mellifera]

Assuming the truck is negative ground, you should have battery voltage on the + side of the coil and the - side should go to the points. I'm not sure what to make of the voltages you've provided, but it doesn't sound right.

I think I would completely bypass the wiring harness. Disconnect the low tension coil wires. Jumper from battery + to coil +. Jumper from coil - to points. Start truck then turn off key. The truck should still run, but you will have (hopefully/in a normal truck) disabled all switched 12V. This will isolate it as either a wiring problem or a distributor problem.

At this point, I'm leaning toward an improperly isolated points set, which is easy to do, or some other fault inside the distributor.

You say that it will run either on 1 and 2 or 3 and 4. Will it run or 1 and 3 or 4 or 2 and 3 or 4?

[Lance]

I'll try reversing the wires on the coil. Almost seems like something is drawing the coil down. Has enough spark for two plugs, Pull wires off 1&2 then 3&4 work.
From earth to negative side of coil has steady 10 volts. Positive side of coil has 13 volts. Across coil (neg. to pos.) I have 4.5 volts. Does that sound normal?

[Apis Mellifera]

I suggested cap, wires and rotor in post 6. In post 7 he said he's already replaced them.

I've heard that if the coil is wired backward it will do strange things spark-wise. Also, there is an arch from the valve cover to ground? Isn't the valve cover either grounded already or if the gaskets are in good condition, isolated completely?

[Lance]

I will check the ground strap.

[Nium]

Ground strap

Is the ground strap from engine to chassis sound?

[albersj51]

I agree with Mark. It sounds like really bad plug wires.

[SafeAirOne]

I'd change the plugs and wires and probably the rotor and cap too. Then you've eliminated any leakage anywhere in the secondary circuit.

[Lance]

Don't know if anyone is still out there but I think I'm on to something.
Yesterday I was working on the Rover again & found that if I unplug spark plug wires 1&2 then 3&4 will fire BUT when I do this I get a spark that is jumping from the valve cover to anything grounded! If I plug 1&2 back on then 3&4 stop firing the spark goes away & 1&2 start firing. Something shorted??? where to look??? I have swapped dissy with spare but that doesn't change anything.

[Lance]

Will do, won't be able to try this until tuesday. Had to call it a day.
Thanks for the help.

[Apis Mellifera]

Since you're switching wires try these configurations (looking at the cap):
31
42

12
34

24
13

43
21

[Lance]

OK I put the timing light on all the wires #1 & 4 both look the same on the flywheel, the timing marks are there. I switched wires 3&4. Putting 3 on 4 & 4 on 3 (getting zapped in the process....I have good spark). Still no change. I haven't started it in a few days and it is very cold here now some I needed a lot of choke to get it started, I don't think it was my imagination it sounded pretty good like running on all 4 but then it went away & back to two?

[Apis Mellifera]

Well, in that case, try starting it up and spraying the inlet manifold around 3 and 4 runners with WD40 or some such. Could be a massive vacuum leak. If that's the problem the exhaust note will change. If you use spray ether, just use short blasts.

If that's not it, I give up.

[Lance]

Don't worry about insulting me, I'm pleased to have you guys helping. I soooo want to fix this and go for a drive! I put the timing light on the front plug wire closest plug to the front of the vehicle. I didn't try putting it on other plugs but I will just to see what happens. The dissy rotates counter clockwise. Firing order is 1 3 4 2. I have #1 wire going to the top front (right) plug on the cap, then going counter clock wise next is 3 4 2.

[Apis Mellifera]

The dynamic timing may be near 40 degrees. You have initial static timing, which is what you measure on the crank pulley or flywheel, and you have the mechanical timing provided by the distributor. To find out what the distributor timing is you take the points plate off and look at the weights. There will be a number stamped on them, say 15. Multiply that by 2 and add the static timing of, say, 10 and you'd have 40 degrees total. It's possible the small springs inside the distributor broke, producing max mechanical advance at all times.

http://www.jcna.com/library/tech/tech0015.html

That might help my explanation.

That said, as was mentioned, given the info you've provided, anything timing related that suddenly happened would have caused all cylinders to misfire. Humor us and simply switch 3 and 4 plug wires to see if that does anything. If that doesn't help, and as you said, you have spark and compression on 3 and 4, it has to be inlet related. I can't think of anything else that could produce the same results based on your tests.

The valves are working
The valves are gapped
There is spark
There is compression
The front two cylinders are working properly
The misfire was sudden
The firing order was checked

This doesn't add up to a misfire on 3 and 4 - I'm stumped.

Just to be sure, your wires should be CCW 1-3-4-2... You can get it backward and still have two cylinders correct.