Lead Replacement

Just had a guy say I didn't need to run lead replacement in my 1967 Farmall 706 Have been since I got it was always told if its older than the '70's that you should looking for your opinions.

All that stuff is is a snake oil made to rob you of your $$$ and it does not even have so much as one drop of lead in it. So yes you do not need it and never did. I have never used it in any of the many tractors I have and have yet to have any problems. Tractors where made to be run on the cheapest lowest octal gas made and back in the day the stuff you had delivered to the farm was not even the same stuff you got at the gas station

Old is correct. Jim

Tetra-Methyl-Lead was added to gasoline as an antiknock compound and is a flame retardant. It tends to prevent preignition spark knock in high compression engines. Gasoline with no additives to prevent spark knock will ignite in a hot cylinder via compression alone hence the knock since the ignition often occurs too early in the compression cycle. Lead is still used in older piston driven aircraft (and NASCAR) with the approval of the government because these engines have very high compression and other additives can't prevent spark knock. Tractor gasoline engines never came close to having the compression ratios needing high octane gasoline. Older automotive engines do not do well on unleaded gasoline until rebuilt with a different cam to change the valve timing and the compression ratio had to be reduced. Since tractor engines were made to run on almost anything knocking is not a problem. If you needed more antiknock compound in your gasoline for your tractor you would know by the sound of the engine running. Otherwise the lead does absolutely nothing to help your tractor engine. Direct timed fuel injection also will eliminate the need for antiknock compounds so that modern gasoline has fewer antiknock additives. It would be intuitive to assume that gasoline without a flame retardant would perform better than otherwise since it would burn more completely.

Agreed on all. Lead hasn't been added to fuel in any measurable manner in nearly 30 years. Even "regular" in the early 1980s was way less than half the lead that "regular" had in the early 1970s.

87 Octane today (RON+MON/2) is higher octane than what was recomended for these low compression engines back in the "day" (RON).

There have been a few posts about Late 50's to mid 60's IH gas tractors here, it seems in some conditions under heavy load they'll melt pistons and do other bad things. Many discussions have blamed today's ethanol laced fuel, using unleaded alcohol free fuels and even dumping or cutting it with 100LL avgas or racing fuel. Search for the posts and learn some. The old tractors wern't particulary high tech or high performance but it seems under a heavy load the new fuel is rough on them. The newer engines with computer controlled fuel injection adjusted with a feed back loop can tolerate it and richen the fuel mixture up to hold off the detonation but the older stuff can get lean and self destruct before you have time to pull the plug. The lead substitute is not an answer and doesn't help. In my opinion the energy density of the new fuel is a little more varible and the engine can get too lean real quick. The alcohol is an octane enhancer and maybe the remaining petroleum fraction is not as refined or is of a lower quality.

With respect. What I believe:
The fuel today is much better than the leaded mix that we remember. It may not have the shelf life, and it may remove varnish and other deposits from ancient fuel evaporation, but it does not eat sparkplugs, it does not detonate until we put it in engines with compression well above those in tractors of that era. It is a leaner mix. It does in some cases need greater fuel flow to keep from being lean edge. but not more than 1 to 5 percent. Non adjustable carbs from the mid 60s might need a jet size increase.
It is necessary to find evidence that is not one persons opinion. I will run fuels that prevent detonation in engines I operate. Detonation and spark knock are the real enemies of engine survival. Lugging the life out of a 6 cylinder IH engine because you could do that to an M is not the fuels fault. Jim

i don't know about the different type of gas then and now but my grandfather had a boat gas tank with five gallons in it he died in 1979 i know it was good because my cub burn all of it and what ever was in it cause the cub to quit blowing smoke out the exaust

Don't know about a 706, but when power kero stopped being sold here, Dad just ran the Farmall M on 'Standard' petrol and then on unleaded. Hasn't done it any harm at all in over 25 years.
SadFarmall

In case you havent noticed NASCAR is using ethanol just like you get at the pump

(quoted from post at 12:40:27 10/01/12) In case you havent noticed NASCAR is using ethanol just like you get at the pump

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Yes, and the Indy 500 cars all were powered with E85.

(quoted from post at 06:40:27 10/01/12) In case you havent noticed NASCAR is using ethanol just like you get at the pump

Click to expand...

Correct.... As of the 2011 season, the three touring NASCAR series (Cup, Nationwide and Truck) use Sunoco Green E-15. Before that they used what was basically leaded blue aircraft gas.

Some very old engines had valves and seats made of material that would burn without the protection of the lead deposits left by leaded gas. When low-lead gas first came out these engines needed tetraethyl lead added. However, very, very few of those engines will not have had valve jobs by now (and thus have valves and seats of modern materials), and the "lead subsititute" has no lead in it anyway. It raises the octane, but that"s all.

If you have a 1940"s engine with original valves run it on avgas. Otherwise, don"t worry about it.