Running a bit rich...

[spandit]

Nothing wrong with the coil - trust me!

Whilst testing the spark plugs I inadvertently lost contact with the ground point & had 40,000V earthing through me. It's a wasted spark system so it was like being tasered!

Going to try sandblasting the plugs as my cleaning regimen may not be all that efficient. Failing that, I'll buy some more but need to stop it running so rich

[spandit]

Well, gave the plugs a good clean - sandblasting is really very effective! Put them back in and engine ran beautifully, albeit a little fast. Turned the idle speed down (with the throttle stop screws) using the sync tool as a guide (they were both reading about 65).

Still fouling the plugs, really quite quickly.

Checked the choke gaskets - they seemed fine (and spraying with carb cleaner during running doesn't seem to have any effect). Air filter is pretty clean - it's not brand new (as it's not an item I can easily pick up locally) but I've blown it out with compressed air.

After ANOTHER plug-remove-clean-reinstall session, I started the engine (she's starting straight away without any choke at all) and locked the throttle at about 2,00rpm for about a minute - exhaust looked pretty clean and when I took the #1 plug back out (because it's the most accessible) it was still pretty sooted up, aside from the top of the electrode, which was clean.

I've currently got the mixture screws turned in all the way and out HALF a turn only. I might try running again with them turned all the way in. If the engine does idle/run like this - what does it indicate?

[spandit]

Right, after reading a few posts on here, decided to check the float levels - they were a bit high so spaced out the needle valves a bit and got them closer.

Took her for a drive - the first 1/4 mile was horrible - popping and banging all over the place. After a bit of pedal to the metal, however, she ran a lot smoother. Stopped briefly at a friend's house where I sat idling for a few minutes. Driving off again, we were back to the old banging/popping (until I got down the road a bit further).

So, still running rich at idle and fouling the plugs - would lowering the float levels any more help with this? At least she's running, though and although it's a PITA, I can quite easily swap out some clean plugs in the field should I need to.

[spandit]

Decided, in desperation, to start stripping the carbs down and checking/cleaning everything. Was just checking the idle jets (behind the little cover) when I noticed that the cover, which was pretty dirty, had "OBEN" ("above") written on one side of it. Glancing at the back it was obvious that it was meant to go one way up but they were both installed upside down. I admit, this was done by me, by chance, on a previous occasion.

Reinstalled them both the right way up and the engine wouldn't run - which is a good thing because before, despite the cold, it was bursting into life and fouling the plugs. I've now got all the mixture screws fully in so can reset them and start tuning properly. Have ordered a Colortune which I'll pick up this afternoon.

Fingers crossed this was the problem...

[spandit]

...it wasn't (this is turning into a bit of a blog!)

Picked up the Colortune and it works really well, although I still couldn't get the flame blue at idle. With a few revs it was a nice colour.

I then took the front cover off the engine. A bit of history here: I've installed MegaJolt electronic ignition onto my engine - to make best use of this, it requires a vacuum feed. I'd installed a T-piece in the balance line between the air intakes, with a fuel filter in it for damping purposes. I noticed, whilst round the other side of the engine, that this fuel filter had more fuel in it than the actual fuel filter! I'm guessing that this line has filled with fuel and thus regardless of what the carbs are metering out, there's still more available. I plugged the line, which will affect the timing (I'll have to put a vacuum line elsewhere - I wonder if my brake servo is full of fuel?)

I also dramatically lowered the float levels as they were a bit high - the combination of these things gave me some lovely blue flame inside the cylinders!

Now think the float levels are too low - I didn't have any thin spacers so had to improvise, but once they're at a better level, I'm hoping for great things (because I'm sure the neighbours are getting a bit fed up of the huge bangs from the unburnt fuel igniting in the exhaust!)

[krick3tt]

Never heard of color tune. What is it?

[edzz]

Never heard of color tune. What is it?

http://www.autoexpertproducts.com/colortune-14mm.htm

[audiocontr]

Color tune is interesting! Do they work well for a pinz?

[spandit]

Yes, pretty well. The fact that the engine is inside & the plugs are recessed makes it easier to see the colour. I haven't tried it on cylinder #4 yet, though

[spandit]

Running out of options here. Still fouling the plugs at idle. Thinking the mixture seats might be buggered - guessing that's not an easy thing to fix...

[Jimm391730]

Thinking the mixture seats might be buggered - guessing that's not an easy thing to fix...

The idle mixture needles are a "fine tune" to the mixture; closing them completely or opening them all the way does affect the way it idles, but it will still run either way.

Have you checked that the "choke" (actually an idle enrichment system, since it doesn't "choke" off the airflow) is working correctly and fully disengaged? Since there is no choke butterfly, opening the throttle just bypasses the enrichment and the truck will run fine with the throttle open (unlike a true "choke", which won't run worth a darn if the choke stays closed). The enrichment system is on the passenger side of the carbs, opposite the main jets, with the "choke" cable that runs through the levers. Try disconnecting the cable and move the levers by hand to the most forward position; this will be no enrichment.

I haven't had to mess with this system much so I can't say what could be wrong within the carbs, but I do know that the levers open addtional air passageways that bypass the throttle (to increase the idle speed) and adds extra fuel to that airstream for enrichment.

[spandit]

Choke levers are both fully forward - gaskets are good and holes are clear.

What I'm trying now is this:

1) undo the throttle stop screws until the throttles are completely closed
2) wind them back in again until they'll grip a piece of paper
3) set the mixture screws to 2 turns out from full in
4) try to start the engine
5) wind the throttle stop screws in half a turn at a time until the engine will actually idle

It's not easy getting a screwdriver onto the forward carb throttle stop, is it? Oil filler tube is directly in the way

[audiocontr]

I used a stubby flathead and ground the blade thinner

[spandit]

Think that's what I'll do too.

Annoyingly, left the truck overnight with clean plugs, mixture screws out 2 turns, throttles only just open. Started straight up this morning (and there's a frost) without choke... WHY IS IT SO RICH?

[audiocontr]

Just a guess here - maybe the jets have been modified? maybe too large? At this point, I'd send them to Jim =)