- Joined
- Aug 7, 2007
- Messages
- 2,384
- City
- Michigan
- Vehicle Year
- 1984, 1997
- Transmission
- Manual
- My credo
- If you're not making mistakes, you're not learning.
Dad is yelling at me to get some of the other projects out of the barn before I start new ones, which I suppose is fair.
So I dig out the old 8N that the engine was "rebuilt" by me and him nearly 10/12 years ago now. I never got to finish it, he had some health problems, I had left for college by the time he was better, so there was several years between disassembly and reassembly.
The problem:
We've got it down to weak/intermittent spark.
The engine won't even "pop" when using starter ether, at all. It's as if nothing is happening.
Originally started out as no spark. Dad was told years ago by an "expert who knew everything" that we didn't need the ignition coil resistor. Some old farm hands I talked to more recently said, "oh hell yes you need that, you'll burn out your points and coil in a jiffy". And that set in motion the list of new parts.
Replaced ignition coil resistor - no spark
The we did points (yes, they were very dead)- VERY intermittent spark, and very weak.
so we figured, the coil looked pretty old, could have been damaged, replaced that - slightly more consistent spark, VERY weak.
Dad ran panel wires for a number of years for assembly line robots. SO the wiring is good.
Checked spark with a spare spark plug wire, worked alot better.
*this was a modern high energy plug wire, which I was also told shouldn't/doesn't work near as well as the old style copper core wires*
Wires were old too, so we got a set of new wires (copper core wires). They're trim to length, but we've checked the conductivity for all of them, and all have been making good contact. (slightly more intermittent spark, weak when it does spark)
The book said .015 gap for a front mount distributor (ours), we checked it and found that we had nearly 90° of crank rotation with the points closed.
re-gapped for .025 (angle distributor spec) and now have 5°-10° crank rotation with points closed.
NOW it changed, it sparked good the first time around, 2nd time around it was very weak, then it disappeared entirely and hasn't returned. Yes, the points were tightened down.
The cap is new and the rotor is also new.
It still doesn't pop or make any indication that something is fireing in the cylinders.
Cylinders 1,2,3 are at about 90 psi (minimum), 4 is at 80 psi. which would probably run a little wierd, but not cause NOTHING to happen at all.
The timing has been checked, checked again, and rechecked a third time. Compression shoots up and when the plug does decide to fire, it's immediately after the compression tops out.
The regulator is the only electrical thing we haven't replaced, though it's not even hooked up at the moment. We're desperately trying to just get it to make some kind of noise, anything.
The annoying part? When it was running there was no cylinder head gasket between ANY of the cylinders. It brush hogged and plowed.
After replacing the head gasket, it began belching out exhaust and burnt oil smoke out the oil fill cap, which meant the rings were gone and thus lead to the rebuild. Still, it RAN and brush hogged and plowed.
I'm out of ideas. I've tried every form of reasonable diagnosis I can think of... ANY help would be appreciated. Everything I can think of that would help I've already tried.
So I dig out the old 8N that the engine was "rebuilt" by me and him nearly 10/12 years ago now. I never got to finish it, he had some health problems, I had left for college by the time he was better, so there was several years between disassembly and reassembly.
The problem:
We've got it down to weak/intermittent spark.
The engine won't even "pop" when using starter ether, at all. It's as if nothing is happening.
Originally started out as no spark. Dad was told years ago by an "expert who knew everything" that we didn't need the ignition coil resistor. Some old farm hands I talked to more recently said, "oh hell yes you need that, you'll burn out your points and coil in a jiffy". And that set in motion the list of new parts.
Replaced ignition coil resistor - no spark
The we did points (yes, they were very dead)- VERY intermittent spark, and very weak.
so we figured, the coil looked pretty old, could have been damaged, replaced that - slightly more consistent spark, VERY weak.
Dad ran panel wires for a number of years for assembly line robots. SO the wiring is good.
Checked spark with a spare spark plug wire, worked alot better.
*this was a modern high energy plug wire, which I was also told shouldn't/doesn't work near as well as the old style copper core wires*
Wires were old too, so we got a set of new wires (copper core wires). They're trim to length, but we've checked the conductivity for all of them, and all have been making good contact. (slightly more intermittent spark, weak when it does spark)
The book said .015 gap for a front mount distributor (ours), we checked it and found that we had nearly 90° of crank rotation with the points closed.
re-gapped for .025 (angle distributor spec) and now have 5°-10° crank rotation with points closed.
NOW it changed, it sparked good the first time around, 2nd time around it was very weak, then it disappeared entirely and hasn't returned. Yes, the points were tightened down.
The cap is new and the rotor is also new.
It still doesn't pop or make any indication that something is fireing in the cylinders.
Cylinders 1,2,3 are at about 90 psi (minimum), 4 is at 80 psi. which would probably run a little wierd, but not cause NOTHING to happen at all.
The timing has been checked, checked again, and rechecked a third time. Compression shoots up and when the plug does decide to fire, it's immediately after the compression tops out.
The regulator is the only electrical thing we haven't replaced, though it's not even hooked up at the moment. We're desperately trying to just get it to make some kind of noise, anything.
The annoying part? When it was running there was no cylinder head gasket between ANY of the cylinders. It brush hogged and plowed.
After replacing the head gasket, it began belching out exhaust and burnt oil smoke out the oil fill cap, which meant the rings were gone and thus lead to the rebuild. Still, it RAN and brush hogged and plowed.
I'm out of ideas. I've tried every form of reasonable diagnosis I can think of... ANY help would be appreciated. Everything I can think of that would help I've already tried.