spark plug fouling on right

elkcagg · Oct 12, 2014

What would cause plug fouling on ¤2 cylinder & not ¤1 side? After tractor was dynoed the plugs were pulled & left side was normal warm & the right was cold & wet. The tractor ran fine before shutdown but if it idles for 5 minutes the plug fouls. Autolite 3116 plugs were used before now champion d23s in now

buickanddeere · Oct 12, 2014

Can't read your mind. What tractor, it's condition and it's history?

Kemper · Oct 12, 2014

Could be a bad plug wire, low compression, getting oil on the plug, carb, mag or dist, any blue or black smoke?

Juicybusa2 · Oct 12, 2014

While your case seems extreme, single barrel two cylinders all seem to have an unequal intake charge at idle and exhibit to some degree the right cylinder reads significantly richer than left at idle. The more heat, rpm and load you apply, the less apparent the cylinder disparity. Two barrel dltx tractors are much less succeptible to this characteristic. Most people tune for the type of use. PArade tractors hotter and leaner. A worker will need to be richer and minimize no load idle time.

elkcagg · Oct 12, 2014

It's a JDG. Fresh build, 600 cubes. It has 265 lbs cylinder pressure consistent each side

buickanddeere · Oct 12, 2014

(quoted from post at 18:23:24 10/12/14) It's a JDG. Fresh build, 600 cubes. It has 265 lbs cylinder pressure consistent each side

Cam and followers, re-ground or as found? Coolant temperature? How rich or lean is the idle and main mixture? Putting around or working?

elkcagg · Oct 12, 2014

I was wondering about wires myself...they are new. I'm running a 4 cylinder mag on it. We are suspecting the mag & fuel at this point but I don't think it's the fuel.. (110 race fuel) I've got a similar G basically same setup but stock stroke & no issues for the last 2 years.

gtx1967jewison · Oct 12, 2014

Does it have a duplex carb & manifold or a single barrel carb/manifold?

Keep in mind with that high cylinder pressure you need a very high energy ignition or the spark cannot jump the gap. Another 'solution' is to gap the plugs narrower.

elkcagg · Oct 12, 2014

It has a bored out DLTX51 carb & murphy's manifold

elkcagg · Oct 12, 2014

Coolant temp barely raises the needle. Work it hard under load all day runs great. Get the load off & run it into the shop & you need a plug.

Kemper · Oct 12, 2014

Try the mag off your other G and see how it does

gtx1967jewison · Oct 12, 2014

Well then it can't be one side of the carb having an issue. Good to know.

buickanddeere · Oct 12, 2014

(quoted from post at 18:35:45 10/12/14) I was wondering about wires myself...they are new. I'm running a 4 cylinder mag on it. We are suspecting the mag & fuel at this point but I don't think it's the fuel.. (110 race fuel) I've got a similar G basically same setup but stock stroke & no issues for the last 2 years.

I assume you are familiar with the firing order, mag rpm and firing interval?

RandyB(MI) · Oct 12, 2014

What's your actual comp. ratio. You may be better off blending to abt. 94-96 octane. I am surprised a 600 cu. in. 2 cyl could "work hard under load all day" and still hold together. Oh well, shows what I don't know.

BushogPapa · Oct 12, 2014

Nothing you don't already know, the Rt cylinder at Idle always sucks Hind Nipple and seldom fires efficiently..so it fouls that plug.
The Richer the idle mixture, the Faster that plug fouls..Operating Temp that Low only makes it worse..

Ron.

BushogPapa · Oct 12, 2014

I had to change the 3 letter word to Nipple to please the "Correct Police"..!

Ron.

RandyB(MI) · Oct 12, 2014

You could have used "teat" since it is the correct farm word for the item you are referring to. LOL

buickanddeere · Oct 13, 2014

(quoted from post at 18:41:38 10/12/14) Coolant temp barely raises the needle. Work it hard under load all day runs great. Get the load off & run it into the shop & you need a plug.

It's never ever going to run decent without fouling plugs until the coolant temp is raised to 195F.
The factory cooling fan could be tossed and install and electric pusher fan with a coolant stat for control. Or install a mechanical thermostat in a plate sandwitched at the top of the head/coolant pipe casting.
Why use a mag instead of a Delco distributor ?

David G · Oct 13, 2014

The others nailed it.

You will also see this on a 4 cylinder engine with common intake ports. The only thing that evens it out on them is that they are usually higher RPM.

BushogPapa · Oct 13, 2014

Not in the days I was associated with them...!!

NNP · Oct 13, 2014

normally those conditions indicate oil fouling on that cylinder,
or a very weak ignition.

I run 3116 in mine and hot, cold, warm, working, idling, no fouling.
carb adjusted as recommended here, good response at all rpm's, the slightest puff of black at the onset of a heavy load.
works fine.

But the introduction of that 110 racing fuel changes things a bit.
Ignition then needs to be very, very good as it is harder to ignite high octane stuff....and with high cylinder pressure..you need ignition lightning.
The right side will fail first for the reasons mentioned.
When I drag raced and ran the good fuel in a warmed over engine, the staging lanes time to get to the line was very important. Take a while to get up there and it was a fight to keep plugs from fouling. Get to the line and get those revs up and no problems.
Race fuel by definition isn't made for idling.....

elkcagg · Oct 17, 2014

You are correct as we are making some progress & I'm glad to say it's not a broken ring as we had thought. It's an ignition problem for sure & I'm most certain that a hotter spark will help me here. Thank you everyone for your inputs here.

spark plug fouling on right

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