Super m fuel question

Brady Miller · Oct 6, 2013

Gents,

My neighbor asked a question about unleaded versus leaded. He seems to think that it was leaded gas back then and that it needs an additive now. Any insight?

I would also like a clarification on the dieseling effect too. What fixes it? Diode? Premium? Another kill switch?

Thanks

Janicholson · Oct 6, 2013

TOday's fuel is just fine. It is higher in octane than the farm gasoline of the M's era. If the tank is clean it will be fine. If varnished up. the new gas will clean it but that is good. Do not put anything in it. It is just fine as is. Do not worry about valves or any engine parts. Getting the lead out of fuel, and far better engine oils have made the major difference between the continuous tuneup needed 50 years ago, and today with auto plugs lasting 100K miles. Jim

notjustair · Oct 6, 2013

Add as many switches as you want - that won't stop dieseling. It is dieseling because the heat of something in the combustion chamber is lighting the fuel without the spark plug. Might be hot carbon in the cylinders or something. You could pull the head and clean up the chambers - that might do it. You could also rig up an electromagnetic cutoff jet for the carb. Riding mowers have those now.

Put it in 4th and ease the clutch out when you shut it down. It's easier and less time consuming.

old · Oct 6, 2013

Dieseling is caused by hot spots in the engine which are carbon build up. ATF in the gas will help with that. 1qt to 5gal of gas. As for lead well any thing you buy so put lead in the gas is fake as in not lead at all but a snake oil to cheat a person out of there $$. The gas of today is just fine in the older low compression engines like that SM

D beatty · Oct 6, 2013

We had an M that did that and tried everything and finaily found putting tractor in fifth gear and slowly let out on clutch and killing it to stop dieseling.

gene bender · Oct 6, 2013

They did that 50 yrs ago when Fire-Craters were installed just let it idle a bit. Then stop it in gear when you kill the engine.

kossuth · Oct 6, 2013

(quoted from post at 18:36:31 10/06/13) Gents,

My neighbor asked a question about unleaded versus leaded. He seems to think that it was leaded gas back then and that it needs an additive now. Any insight?

I would also like a clarification on the dieseling effect too. What fixes it? Diode? Premium? Another kill switch?

Thanks

ike the others said it's most likely hot spots on the pistons or on the head itself that is causing combustion after you kill the ignition. It's likely to be just a build up of carbon that's holding heat. I would try Seafoaming it or something along those lines to see how much you can cleaned out of it.

Bud Kaiser · Oct 7, 2013

Check the timing. Try retarding it a little. This fixed mine.

DaninKansas · Oct 7, 2013

A lean carb or timing too advanced gets things very hot and will cause dieseling.

mkirsch · Oct 7, 2013

None of the lead additives have any lead in them. About the only thing they do is make your wallet lighter.

For what little most old tractors get run these days, even if you work them some, it will take DECADES for the valve seats to erode to the point where they need work.

A friend of mine built a 351 Ford engine for his "shaggin' wagon" Econoline van in the 1970's with the soft valve seats. He drove it all summer, every summer, for roughly 30 YEARS, towing 5000lb+ travel trailers all over the country.

Ran nothing but unleaded gas with it.

I think it was about 5 years ago that he finally had to pull the heads and replace them with new Edelbrocks with hardened valve seats. Time flies, so it may actually be less than that.

Super-H-Mike · Oct 7, 2013

Agreed, mine will diesel if its been working hard, letting it idle for 5-10 minutes cures it. I will also use the fifth gear trick if I am in a hurry.

Rick Remmert · Oct 7, 2013

Stopped in Salina, Ks. yesterday on my way back from the Nascar race to fill up with gas. They had 87 octane there for $3.11. I noticed on the pump there were 2 87 octane buttons. The other one had a sticker that said "pure gasoline", no ethenol added. I assume it was pure unleaded. It was $3.45.

Jim CIn. · Oct 7, 2013

Always let a hot engine idle for a few minutes, that will cure the dieseling.

Super m fuel question

Brady Miller

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Janicholson

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notjustair

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old

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D beatty

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gene bender

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kossuth

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Bud Kaiser

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DaninKansas

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mkirsch

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Super-H-Mike

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Rick Remmert

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Jim CIn.

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