3000 gasser no start/poor running

[gears]

Ok everyone, a bit of a bench racing/brainstorming session to help me track down my problem (you know, sitting in front of the computer sipping coffee instead of freezing in the snow actually working on the tractor).

1968 3 cylinder gas 3400. Less than 60 hours on a full rebuild a few years back.

The original ignition switch crapped out over the summer, I bought a new one off that auction site - it's not quite the same, has a glow plug heat position and uses 5 pins on the back when the original was 4 (with 1 empty). I was pretty sure I matched the terminals correctly but it acted a little funny. The tractor started and ran great. It sat for a month or so in the summer (outdoors) and when I went to use it to help a neighbor with a downed tree, it wouldn't run right. No revs, the exhaust got super hot (glowing) even after only 10 minutes of running.

So I figured it's got to be that Holley carb... So, off comes the carb - and it's spotless! The stupid piston slides smoothly, the jets and passages all flow well. Before I put it back on, I decide to change the plugs. While the plugs are out, why not compression test it; 160, 168, 165 psi. Plugs look a little black but I've seen worse, replaced them anyhow with Autolites. Figure why not do points & condenser while I'm in there. New Standard brand from Oreillys. (Plugs, rotor, cap, & wires were replaced 60 hours ago when I rebuilt it).

No joy.

I have not visually checked spark, I'm planning on replacing the (original as far as I know) ignition coil while I check that (maybe next week?) as I have a spare in the barn. It runs like my VW dune buggy did when the condenser went bad. I just came in from verifying that the coil + is hot both cranking and run position, battery voltage (12.2v drops to low 10s during cranking).

Thoughts, opinions, warnings?

 

[Plays with toys]

Coil should not be hot. My '29 Mod AA would run for a bit and then die. Coil was hot. Swapped coil and no more problem. Don't know why your exhaust is cherry red. Too much gas? Exhaust manifold restricted?

 

[gears]

I should have said the coil positive post had 12v+ going to it. It has the stack exhaust so I pulled the muffler and put a straight pipe to verify, got just as hot. That's what made me think it was carb related.

Nothing has been modified/changed with the dizzy, but maybe I need to verify timing too.

 

[Powered By IH]

Check timing and readjust the carburetor, and go from there.

 

[Sean in PA]

exhaust too hot is usually too lean of a mixture or a timing issue.

 

[gears]

Not sure how timing could've been changed but definitely worth checking.

 

[gears]

Anyone had a case of the intake manifold on these coming loose? I had a Jetta do this but never thought about checking the tractor's intake manifold torque...

 

[gears]

Ok, update. Pulled the coil wire and checked spark - good, strong fat whitish spark. Got it to start (still haven't done anything with timing) ran slow, wouldn't rev, occasional backfiring, and pulled #3 wire - no difference to "idle". Pulled #1 same thing. Pulled #2 and it died - just as though it's running on 1 cylinder.

Going to pull #1&3 plugs and check wire resistance while I'm at it.

When it was a project I didn't mind this sort of thing. Now that I just want to use it...... grrrrrr

 

[Powered By IH]

Ok, update. Pulled the coil wire and checked spark - good, strong fat whitish spark. Got it to start (still haven't done anything with timing) ran slow, wouldn't rev, occasional backfiring, and pulled #3 wire - no difference to "idle". Pulled #1 same thing. Pulled #2 and it died - just as though it's running on 1 cylinder.

Going to pull #1&3 plugs and check wire resistance while I'm at it.

When it was a project I didn't mind this sort of thing. Now that I just want to use it...... grrrrrr

Can you post a picture of your spark plugs and inside of the coil cap?

 

[gears]

I'll get some shots - the cap's center carbon button was worn down almost flush and the rotor's spring steel contactor was tweaked. I replaced both with CNH parts - that's what it started on.

 

[used red MN]

Ok, update. Pulled the coil wire and checked spark - good, strong fat whitish spark. Got it to start (still haven't done anything with timing) ran slow, wouldn't rev, occasional backfiring, and pulled #3 wire - no difference to "idle". Pulled #1 same thing. Pulled #2 and it died - just as though it's running on 1 cylinder.

Going to pull #1&3 plugs and check wire resistance while I'm at it.

When it was a project I didn't mind this sort of thing. Now that I just want to use it...... grrrrrr

Are the spark plug wires in the cap in the proper firing order? If 2 is correct then 1 should be clockwise to it. Then 3 should be counter clockwise of 2. Rotation is counterclockwise and the firing order is 1-2-3.
The unburned gas from cylinders 1 & 3 not firing is burning in the exhaust making it hot.

 

[showcrop]

An exhaust glowing in ten minutes is almost always retarded timing.

 

[gears]

Verified dizzy rotation and firing order (in case some kids playing in the back 40 were messing with it). Will pull plugs and maybe cut new wires for 1&3 while I'm taking resistance readings, Before checking timing.

 

[Hobo,NC]

Ok, update. Pulled the coil wire and checked spark - good, strong fat whitish spark. Got it to start (still haven't done anything with timing) ran slow, wouldn't rev, occasional backfiring, and pulled #3 wire - no difference to "idle". Pulled #1 same thing. Pulled #2 and it died - just as though it's running on 1 cylinder.

Going to pull #1&3 plugs and check wire resistance while I'm at it.

When it was a project I didn't mind this sort of thing. Now that I just want to use it...... grrrrrr

Test at each plug wire at the spark plug end. You can also test running. untill you prove your spark claim spark is in doubt. Get a spark tester and eliminate guessing.

spark tester guess eliminator

 

[gears]

Thanks Hobo, I've always just held the wire away from ground and cranked or pulled.... gotten bit a few times for my trouble. Ordered that one you linked to off that auction site. Looking forward to getting some answers next week!

 

[gears]

Ok, so it was more than a week. Let me start by quoting George Strait: "I hate everything..."

Got the spark tester, checked for "S/E" spark from coil - good. Through cap/rotor/wires to plug - good. Check timing, good. Still running on 1 cyl (#2). I can pull #s 1 & 3 (getting slightly bitten through insulation on pliers). No joy...

Pulled the "new" plugs out of 1&3 (NGK) and they are black and dry. Start it on #2 letting 1&3 dangle on the manifold - can see spark on both.

Figure since I have them out I'll put the Autolites back in.

RUNS PERFECT!

It was not running like this when I pulled these Autolites to check compression in the Fall.

Anyhow, thanks to all who chimed in (Hobo, that spark tester has a special spot in my "electrical" drawer), figured I'd give this thread some closure.

 

[Hobo,NC]

Sounds like your spark plugs were carbon fouled. spark plug color chart I dunno what you mean by S/E I hope you adjusted the checker to the 2/0 setting.

 

[gears]

The "S/E" marker is opposite the "0/2/0" indications as shown in your posted pic linked above. Same gap...

 

[Hobo,NC]

I picked the tester up and snaped a pix then put the red line @ 2/0, 2/0 is 20KV for automotive conventional ignition (point type). I knew when I posted this photo it may confuse someone that's why I added the instructions. SE is for small engines lawn mowers and such. 2/0 Is for your tractor.

An ignition coil will put out enough spark to jump a normal gap, life's good everyone is happy. When you induce a situation when it has to jump a larger gap as you did by letting the spark find ground by letting the plugs dangle a ignition coil will boost spark output to bridge that gap.

A discussion on this Spark

You could also put his in your search bar More about spark

 

[gears]

Sweet. Thanks for the links Hobo. I also knew that the plugs dangling weren't in a compression environment and so just seeing them spark out in the open didn't mean that they'd do the same thing under pressure. Now, I just need to throw them out instead of leaving them on my workbench where they'll eventually find their way into my bucket of spare plugs...