Tractor Vet - Farmall 656 Gasser Information Needed??

Farmallhal · May 11, 2012

Recently purchased a 1967 Farmall 656 gas tractor and have been reading through the Owner's Manual as to specifics unique to the tractor as I have never had a 6 cyl. Farmall before. I know you have beliefs on the proper fuel to be used and would like to start it's life off with me on the right track. The manual states "this engine is designed to operate on gasoline with a 93 minimum octane rating (research method)" so think I will be needing to use preminum fuel with this one. Gas today (unlike pre-ethenol days) has an octane rating based on the research method along with another standard which is averaged I believe. What gasoline product should I be using in current octane ratings with this tractor? The tractor's main use will be with my New Holland 273 small square baler and with a 10' Bush Hog clipping summer weedy growth on my pastures. It may get some tillage type use later when I need to replant some of my hay fields once I obtain a plow for it. Thanks much for any and all responses relative to this matter, Hal.

Anonymous-0 · May 11, 2012

I have one too it does good on regular gas. No ethanol though doesnt run worth a crap.i have nnever tried premium

mkirsch · May 11, 2012

Hal, I recall a recent post from tractor vet where his neighbor melted a piston on his 706 because the fuel supplier started filling his bulk tank with 93 octane, 10% ethanol gas.

So it seems even when you use 93 octane fuel and everything else is right, it has to be PURE gasoline or you're in trouble.

Sure wish we could get to the bottom of this whole controversy... I know some guys dump the cheapest gas they can get into 'em, run 'em hard and put 'em away wet. No problems. Then there are other guys who do everything right and melt pistons just pulling the dang things out of the barn...

the tractor vet · May 11, 2012

Well all you can do NOW is run the 93 that we are getting shoved down our throats . Get yourself a GOOD timing lite and make sure that the ing. timing is set dead on . When setting ing. timing you set for full advance at high ideal or wide open . Run a cold plug make sure the heat riser in the exhaust manifold is working and the thermostat is working. Also confirm that the advance is working in the dist. With out running out to the truck and check what the timing is on your tractor i will not guess on it . And here again i am not sure if you have a C263 or if they stuffed a C291 in it like they did on the 706's . I know some area's guys can not get 93 and it seems that all the 93 now has ALki hol in it and i am telling you this is not good. I have been talking with a fuel supplier about getting some BLENDED gas as he has told me that the best gas he can get is 90 octane that is straight gas and then getting some 100 LL aviation gas and blending it, but at what amount . Would 50 gal of 100ll be enough to bring the 90 up to 93-94 ???? don't know. We were thinking about getting 250 gallon of the 90 and adding in 50 of the 100 LL . If i am wrong and more then likely i am it can get costly and time consuming . I do not get my Jollys off pulling heads and removing scrapped out pistons . I am running out of answers and idea's here.

mkirsch · May 11, 2012

I'm a math guy so maybe I can help...

If you mix the 90 and 100LL together 50/50, you will end up with 95.

At 250/50, you will end up with 91.67.

To get 93, mix 100 gallons of 90 with 50 gallons of 100LL.

the tractor vet · May 11, 2012

They DID run just fine when ya run the correct fuel and have them tuned dead on the money . i have been running them gasser since 1975 . Now even BEFORE i ever had and owners manual on one i used high test gas as that is what i have always run in every gas powered piece i have owned . Now with me working on tractors a lot of the work i did was for the LITTLE guys that more or less hobby farmed on a shoe string budget and 90 % of the problems they were having with there tractors was fuel related . Also due to there fuel suppliers not flushing out the hose or draining the compartment and making sure that they did not dump a couple hundred gallon in on top of 50-100 gallon of diesel and have the hose full of diesel . This does wonders on starting problems and sure does a wonderful job on plug life along with excess black smoke out of a gasser . The 87 Octane fuel burns way hotter then the 93 and a whole lot faster , you do not get the longer burn off of it as you do with the 93 . Before gas prices went thru the roof 93 was only a few cent more and now it is 20 cents more . Ok so it is 20 cents more and 200 gallon will cost ya 40 bucks more . This comes down to it will take you about 800 gallons to equal the cost of one piston , one set of rings and one head set and one pan gskt. over the 87 . We go thru about 600 gallons a year on our 706 and it is the most used tractor over the 806 D and the 1066 .

Anonymous-0 · May 11, 2012

Farmallhal, go to the wikipedia "octane rating" and you will find that tv and mkirsch are full of beans. 93 rm fuel is now 89 r+m/2. Nascar runs ethanol in way higher compression engines. You melt piston by running LEAN you break pistons by being mistimed. We've used E-10 (89octane) in everything for 30+ years, no melted pistons, and no need for dry gas in winter.

Anonymous-0 · May 11, 2012

And tractor vet we are NOT hobby farmers, just not smart enough to work on diesels in the farm shop and to cheap to buy newer when the gassers we have do the job. $125 per hour shop time for our diesels. I have to believe that the combines work as hard and as long as those 706s, full rpm for 10 hours a day and have never had problems w ethanol.

the tractor vet · May 11, 2012

Ouch this is not going to work out . Back to the drawing board. Wonder just how many old gas tractors are out there still earning there keep not a trailer queens or play toys ?? For us and the neighbors there are 4 S/MTA's two John Deere A's two 460's five 706 gassers a WD 45 A/C a John Deere B and a 50 6 Farmall 400's and 450's And that is just around me that are on working small dairy farms And the BIG power is the 1066 and Vernon's 2255 Oil all over that is broke down Again with a locked up transmission. So we have nothing new but will used . even the diesel fuel is causing head aches for the older tractors , Just ask my pump guy he is loving it as he has told me that he has never been so busy .

the tractor vet · May 11, 2012

You may not notice it but i sure did on my Massey 300 . I tried running it on the 87 and i could not figure out why it was always running well over 200 degrees . First thing was wash and blow out the rad, no help there changed the water pump , nothing there changed the T/stat Nope that did not help , check the timing nothing there pulled the rad out and had it rodded and flow checked , that did nothing but re-leave me of fifty bucks . BUT when i put the same gas in it that i was feeding the 706 it dropped down to 190-195 on a warm fall day running thru 178 Bpa corn in second gear half way up on the variable speed . so this showed me that the gas was my heat problem on it before we had a problem with the 706 and before we had the gas lab tested over the melt down. as for doing your own work on a diesel and not being able to do it yourself WHY . You know how to work on a gasser and there is not that much difference between it and a diesel. JUST NO SPARK PLUGS .

the tractor vet · May 11, 2012

No it is not research method is research . I am not the only one with fuel related problems . But what ever you say and myself i could give a rat arrses about a NASCAR engine as it only has to last 500 miles or about a couple hours and it is scrapped when done . Just like a double A alki hol dragster only has to last 5 seconds and then put in new pistons IF the block and head survive . How many 487 Donaven's have you built or 426 hemi's or DOHC 427 have you put down the track or ran on a dyno ???? how many first places have you earned over the years???? I can back up what i know about this stuff. And oh BTW them NASCAR engines are not running on the same stuff you get at the farm.

Country Nate · May 11, 2012

Since I took Vets advice and started using 93 in my Case gasser it runs 5 to 10 degrees cooler. And no more run on when you shut it off. The tractor likes ot better, so I will continue to use it.

dhermesc · May 11, 2012

For some reason our gas 656 with over 20K hours runs fine on regular. Granted it is on its third overhaul but then it's also had good operators and mechanics working on it.

mkirsch · May 11, 2012

gtski, since you're so smart, explain to me how you RICHEN a C291 gas engine and get any useful power out of it?

One single drop more fuel than that stock solenoid passes, and the tractor is blowing black smoke and can't get out of its own way. In other words: TOO RICH.

What's your magic solution?

dej(Jed) · May 11, 2012

(quoted from post at 05:25:24 05/11/12) Recently purchased a 1967 Farmall 656 gas tractor and have been reading through the Owner's Manual as to specifics unique to the tractor as I have never had a 6 cyl. Farmall before. I know you have beliefs on the proper fuel to be used and would like to start it's life off with me on the right track. The manual states "this engine is designed to operate on gasoline with a 93 minimum octane rating (research method)" so think I will be needing to use preminum fuel with this one. Gas today (unlike pre-ethenol days) has an octane rating based on the research method along with another standard which is averaged I believe. What gasoline product should I be using in current octane ratings with this tractor? The tractor's main use will be with my New Holland 273 small square baler and with a 10' Bush Hog clipping summer weedy growth on my pastures. It may get some tillage type use later when I need to replant some of my hay fields once I obtain a plow for it. Thanks much for any and all responses relative to this matter, Hal.

Pump octane is R+M/2. There is a Research octane number and a Motor octane number. We seem to be getting confusing. A 92 Research and an 82 Motor would produce a pump octane of 87. An 87 octane pump gasoline should work well in the 656 -6 cylinder. I use it all the time and have no problems.

Anonymous-0 · May 11, 2012

We run E10 89 octane (R+M/2), $0.06 over 87 regular, in everything would have been about 91-92 by the old method again never had a problem. The only thing we don't do with the diesels is the pump/injectors cause we have no equipment for that.

dhermesc · May 11, 2012

You know what's strange - hundreds of thousands of other tractors have the same experience.

wisbaker · May 11, 2012

Blending 100LL and autogas- the line is a curve! Mixing 100LL in lead free doesn't give you an average of the two fuels, you get more octane increase with the first unit and each successive unit of 100LL gives you a lower return on octane. You might very well get what you need with 10 to 20% 100LL avgas. I'd start at 33% and work my way down to 10% checking to see what changes. Look at operating temperature, if you have one of those IR thermometers I'd scan the head, exhaust manifold and muffler/stack and see.

wisbaker · May 11, 2012

Just looked at a pilot's forum if your aircraft has been STC'd (airplane speak for modified) to run autogas and you set it up to run Autogas but run 100LL your engine will run RICH if your engine is set up to run on 100LL but fuel it with with autogas it'll be lean, in fact lean enough to cause engine damage. Rotex (airplane engine manufacturer) recommends setting their engines up to run on Autogas but occasionally run a tank of 100LL through it. One forum pointed out that airplane engines are low-speed and relevantly low performance , a Continental IO 550 is 550 cubic inch engine rated at 300-301 horsepower. Low speed because you have to keep prop speed below the speed of sound or airflow over the prop gets messed up and your prop efficiency goes to heck. Pilots don't like gear boxes, they add weight and it's something more to go wrong, and a smaller engine turning more RPM's doesn't usually last as long. Another interesting comment is aviation fuels have different vaporization characteristics because they are made to be used at higher altitudes.

CNKS · May 11, 2012

gtski is correct in that the R+M/2 octane measurement is about 4 points lower than the research method. In other words 87 octane by the R+M/2 method is about 91 octane by the research method. The 89 octane that gtski runs is about 93 octane by the research measurement. I don't think there is a fixed standard, and different companies may use different values for their research or motor number. If you use 93 octane by the R+M/2 method the research number is 97, seems like overkill.

John M · May 11, 2012

I did have something else typed up, think Ill just let it go!! TV is going preach 93 octane no matter what, so let him! When he can provide the PROOF that he claims to have, then maybe, just maybe, Ill listen!

Farmallhal · May 11, 2012

Thanks for all the discussion and as always this brings a lot of opinions into play and with the removal of lead and addition of ethenol to our gas has certainly been detrimental to our old tractors. As summerized from comments of others by CNKS it appears todays 93 octane is not the same as the old 93 octane of the era when my 656 was produced in 1967 but something even higher in octane rating. There is a service station in town (that's correct not a quick mart type store that also sells fuel) that has 91 octane un-blended preminum gasoline without any type of alcohol available. I believe that might just be my best available choice. Maybe I need to get a truck bed fuel tank with a hand pump to bring it out to the farm for the 656 along with a good lead substitute if there is such a thing available. Thanks for all the discussion and your comments relative to this matter, Hal.

mkirsch · May 11, 2012

One thing I think we can agree on is there is no such thing as "good" lead substitute. It's all snake oil, and the only adding it does is add your money to their bank account.

wisbaker · May 11, 2012

Okay let's beat a dead horse, I just checked density and energy density on Gasoline, Gasohol, Ethanol and Methanol. Ethanol is more dense than gasoline- gasoline runs .71-.77 but Ethanol is .789 and if is has any water in it it'll be more dense (mix 1 cc of water with 1cc of ethanol- the resulting mixture will occupy about 1.97cc'c). It might very well have water in it, pure ethanol will absorb water from the air, I'm thinking that they blend 180-190 proof (90-95%) into gasoline. Looking at the Energy Density- or how much energy is in the fuel by weight- Gasoline 46.4 MJ (MilliJoules?)per gram, Gasohol (10% ethanol 90% gasoline) 43.54 MJ/g, Ethanol 30MJ/g and Methanol 19 MJ/g. I wonder if the detonation and resulting melted pistons is a function of the engine being lean. I say lean because we mix the fuel with air by volume but we see with 10% alcohol the mixture has fewer MJs or BTUs (energy). Could the lower energy input in the cylinder mean the combustion is hotter as it would be if the engine is to lean? Or does Alcohol burn hotter than Gasoline?Here in Wisconsin Shell and BP advertise alcohol free premium gasoline.

CNKS · May 12, 2012

Hal, I don't have a 656, etc, I do have a 460 where 87 octane by the research method is required, the compression ratio of the 263 in your 656 is the same as in my 460, 7.2:1, although there could be differences in the engines that require a higher octane. But, I think the most important thing in this octane discussion (that repeats itself every week), it seems is DON'T overload the tractor. Tractor Vet will shoot down my comments, but my understanding is that he farms very rolling ground, where any tractor diesel or gas will become overloaded, diesel takes it better than gas. It is probably more level where you live. As the saying goes "one size does not fit all". If you have doubts, use 91 octane by the R+M/2 method. I for one am not sure about the effects of alcohol, but I don't even use it in my personal vehicles as they have not yet put it in the 87 octane gas that I buy. But I somehow doubt if it causes many problems particularly if you up the octane a little.

Anonymous-0 · May 20, 2012

Tractor vet also has to explain how he ruined a feshly overhauled engine without getting stuck with the bill.

Tractor Vet - Farmall 656 Gasser Information Needed??

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