? about hotter plugs

[MF85]

I have a MF 85 (okay, stop laughing). I'm no mechanic but I'm forced to start learning due to location, pending purchase of another tractor. The plugs foul FAST! I'll put in new Champion D21 plugs and I lose power within an hour. When I told the MF dealer that I suspected the rings were shot or the head was leaking oil into the cylinders (I do have oil leaking out over the carb) he suggested that maybe my plugs weren't hot enough and that I should try getting hotter plugs (he did not know the type of plugs I was using). My question for you is, what kind of plugs should I try? Thanks in advance for any help.

P.S. It also drinks gasoline like it's going out of style. Any comments?

 

[Soundguy]

A higher heat range plug can sometimes overcome fouling by burning off some deposits.. like from modern unleaded fuels.. orcombustion byproducts.. perhaps a bit of oil.. etc.

For instance.. stock plug for a ford 8n is a champion H10.. though we genrally jump a heat range and use the H12, for the reasons I mentioned.

If you really are pumping oil.. you may try the higher heat range plug, as wella s anti foul adapters.

A mf 85 calls for the champion D21.. that's stock # 502. For heavy usage, they recomend a 555.. a UD16 plug.

If you hop to autolite, that's an AL 386.. same as my JD-B.. 388 is a higher heat range.. etc.

Soundguy

 

[MF85]

Thank you very much. I'm going to give that a try today and hope it buys me a little more time.

 

[JerryG]

If its drinking gas really bad, there may be something wrong with the carb. That could be causing your plug problem. BTW, get a better plug to replace the Champions.

 

[MF85]

It's a new carb but not factory. When I removed and cleaned up the old one (to no avail) I took it in two years ago. They could not find a factory "match" so they put something else on (aftermarket?). It has two adjustments, one is a flat head screw with a spring under it, the other is a screw with a little rod through it at 90 degrees that serves as a handle for turning it in and out. I don't know which one is fuel or air, what they do, or which way to turn them, in or out, or how to tell what the ideal setting is.

I've tried to adjust them with the engine running and the only difference I can tell in sound is when the engine is about to shut down. I end up putting them back where I found them (based on grease/gunk).

Is there a way to tell the ideal setting? Thanks.

I got the hotter plugs, which seemed to work. I also tightend some bolts on the exhaust manifold (?) and the oil leak quit. I figured out how to lean out the carb and that seemed to help. They did not have the fouling reducers but could order them. Things worked for about 45 minutes but I had to stop to do other work. It seemed MUCH better, so far. Thank you all for your help.

 

[Soundguy]

Jerry is right.. champions seem especailly prone to fouling.. and gas fouling is the worst.

Glad you got the oil leak fixed. those al388 plugs should go for a while.

What make carb is it. Many oldies have an adjustable mainjet, adjustable idle jet, and perhaps a idle set screw.

The mainjet will be easy to find. Get the engine out of idle.. then turn ( usually the biggest needle ) .. you will be able to tell enrich/and lean. Get it just rich enough so that it doesn't stumble when you gas the throttle. If it lacks a bit of power.. give it 1/8 more mainjet and try it.. keep doing this till power is good.. but that it doesn't make black (rich) sooty exhaust.. and doesn't 'flood' out.. etc.

Soundguy

 

[MF85]

After editing my post yesterday, I did get out in the rain and ran it for several hours leveling sites and roads. It ran much better. I'm not sure if it was the carb adjustment, tightening down the exhaust manifold bolts, the new hotter plugs, or all three, but unfortunately it's working so well that I may have to put off my dream of buying a new tractor. ****!

I did not look to see carb brand but I put the excellarator on medium idle and turned in the bottom valve (the brass looking one with the little 90 degree pin handle) until the engine started to shut down, then came back out a little. I had to do that one more time and it ran fine.

The top screw with the spring under it was turned out (I assume it was air and I was trying to give it more) but I did not notice much change. I was just happy to get some work done. I will follow your directions more closely next time I get on it and try to fine tune it some more for better power.

The guy at NAPA said Champion used to suck because they tested their plugs for heat ratings with the wrong gas (high end stuff) but they are better now. I bought the Auto lite any way. He did not have the foul prevention devices for my plugs but showed me what they looked like. He said if I ever use them I should first go back to my regular plugs. He used hotter plugs with those preventers once and burned the plugs up. I'm not there yet.

Again, thank you for your help.