re: minimum octane requirements

A couple of weeks ago, I got some recommendations on this site that I should use a minimum of 93 octane gas in my 656 farmall. I had been using mid grade (89 octane rating). My operator's manual says to use fuel with a minimum of 93 octane, research method.

I looked up some information on octane ratings and it said that the research method was approximately 8 to 10 points higher than the motor method. The ratings at the pump are an average of the R & M numbers.

So, if I assume that the R method is only 8 points higher than the M method, then to get an average value of 89 octane, the M number would be 85 and the R number would be 93.

Therefore, isn't the 89 average octane sufficient to use in my tractor? (since it means that the R number is at least 93)

I am going to tell you like this it is your tractor . You can run what you like if saving 10 cents a gallon over say a couple hundred gallon of fuel over a years use is worth and engine then go for it . BUT when ya guild a couple pistons to the sleeves don't come whining as to what happened. Myself i have seen first hand what happens so has our fuel supplier .HE gets us 93 octane fuel with no Al ki hol just straight 93 octane gas and around here we have always been on the research method . We did not start having problems with gas tractors till back in the mid 80's when they made a change with the gas . Also look at all the problems that the change in diesel fuel has cause with older injection pumps . If i had been smart and went ahead and set up and injection shop like i thought about back in 83 i could have been like a buddy that has a injection shop and own my own Beech Craft turbo Baron . So if saving lets say a 100 bucks a year is that important then run the 89.

(quoted from post at 07:06:22 10/19/11) A couple of weeks ago, I got some recommendations on this site that I should use a minimum of 93 octane gas in my 656 farmall. I had been using mid grade (89 octane rating). My operator's manual says to use fuel with a minimum of 93 octane, research method.

I looked up some information on octane ratings and it said that the research method was approximately 8 to 10 points higher than the motor method. The ratings at the pump are an average of the R & M numbers.

So, if I assume that the R method is only 8 points higher than the M method, then to get an average value of 89 octane, the M number would be 85 and the R number would be 93.

Therefore, isn't the 89 average octane sufficient to use in my tractor? (since it means that the R number is at least 93)

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I have no answers, but I think you just may be on to something here.

You can pay the 10 cents per gallon on a LOT of gallons for what an engine rebuild will cost you...

The CaseIH dealer charged Dad $4500 in the early 1990's to do a PARTIAL overhaul on the C291 engine in the 756.

I can't imagine what a full overhaul would cost now. Probably $6000 at least, if you find an independent mechanic to do the work.

You could pay the price premium on 60,000 gallons, yes SIXTY THOUSAND gallons of gas, for what it will cost to rebuild the engine.

BTW, Research + Motor / 2 is the FEDERALLY MANDATED method for reporting octane rating on gasoline. I don't know what part of the world tractor vet lives in where they can get away with just using the Research method. I thought he lived in the USA somewhere.

Local carb rebuilder I know, been at it for 40+ years, will rebuild carbs to run the lower octane gas. Does this help any at all on a moderately used tractor? Or just makes them run a little better.

I don't really care about the octane rating nearly as much as the fact that most or all 89oct. mid-grade gas has 10% alcohol in it. I know I'll catch a lot of flack from farmers that raise corn for alcohol, but alcohol will wash or clean up a lot of things, [u:7a8e13bedf]including some things you don't want cleaned[/u:7a8e13bedf].
In addition, "gas/alky" mix is not as efficient as gasoline so you burn more. I have tried it in cars and mileage dropped to the point that hihg grade was cheaper to run. Had a '98 Linc. Cont. for 10 years that got 25+ hwy. with high oct. and it dropped to 22+ with 89 mix. Didn't take me too long to figure out it wasn't worth it.
As to the octane rating, I think you are all on the same page with the mid-grade actually being 93 oct. [b:7a8e13bedf]R method[/b:7a8e13bedf], but don't want to admit it. BTW, I burn 87 in my 240U, but do not work it hard, so don't see a problem.

You are correct.

Thousands of gas tractors have run millions of hours without issue on 87 octane. The owner’s manual was written before R&M were standard pump ratings. Just as your manual says to use 30 weight in summer and 20 weight in the winter - it was before 10W30 or 15W40 was available - and on older tractors it says to use 30 weight nondetergent - because 30 weight detergentated oil was not available at a price that farmers could afford.

Don I know I said in an earlier post that my cousin has run a 656 for years on 89 octane. But the application was errand tractor (spraying, elevator, etc) not heavy field work. This is the same tractor I ran has a kid in the early 70s field working it. That manifold gets red hot, so do the exhaust valves. Do like tractor vet recommends, don't risk major engine damage.

I can't understand this claim. All you generally have is idle and rich/lean. Is he changing jet sizes? This would help the tuning of the carburetor but couldn't help the firing within the cylinder.

Why would the manufacturer suggest an octane rating that hurts the tractor?

I meant for the question to be at the bottom, sorry for any confusion.

(quoted from post at 08:34:19 10/19/11) Local carb rebuilder I know, been at it for 40+ years, will rebuild carbs to run the lower octane gas. Does this help any at all on a moderately used tractor? Or just makes them run a little better.

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Impossible to make any changes to the carburetor that would allow any engine to run efficiently on lower, or even higher octane gasoline. The carburetor DOES NOT care what the octane rating is. The only way to accomplish that goal is to modify the engine so it has lower compression, or seriously retard the ignition timing to prevent pre-ignition associated with lower octane fuel. Doing either of these measures would also drastically reduce the performance and power of the engine.

so, would a M with a kerosene head run better on ethanol? (don't
the kerosene heads have lower compression) Just wondering.

(quoted from post at 12:19:11 10/19/11) so, would a M with a kerosene head run better on ethanol? (don't
the kerosene heads have lower compression) Just wondering.

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Ethanol raises the octane rating. I've got a 1940 M with the high compression gasoline head and it runs just fine on E-85.

(quoted from post at 08:34:19 10/19/11) Local carb rebuilder I know, been at it for 40+ years, will rebuild carbs to run the lower octane gas. Does this help any at all on a moderately used tractor? Or just makes them run a little better.

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It's not the carburetor that's the issue.

It's the cylinder pressures and temperatures in the later HIGH compression IH gas engines. That is, any post-1958 tractor starting with the 460/560 series.

The old pre-1958 engines are LOW compression engines, and run fine on 87 octane. Higher octane is a waste of money on these.

Lean, rich doesn't make a lick of difference. The low-octane fuel will still go *BANG* too soon in the high compression engines. It's the fuel, not the mixture.

Octane doesn't make any difference in modern cars because there is a computer, a bunch of sensors, and a bunch of controls that change timing, fuel mixture, etc. to compensate. These old engines have one "sweet spot" where they work. Performance and longevity fall off drastically when you start messing with that sweet spot.

Ethanol raises the octane rating. I've got a 1940 M with the high compression gasoline head and it runs just fine on E-85.

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E-85 has an octane rating from 100 to 113 depending on who you ask.

If not for the lower energy content (which causes the engine to run lean) you might think E-85 would be better for the high compression engines.

I have probably put around 500 hours on this tractor with the mid grade 89 octane gas of which at least 300 hours were working the tractor hard. Seems like if the 89 octane was going to damage the engine that it would have done it by now. I recently did some heavy field work with it. I started on 89 octane and switched to the 93 octane when I had to add fuel to the tractor. I couldn't tell any difference in the performance of the tractor.

My basic question is this: Does the 89 octane mid range gas (average of R & M, and which is at least 93 by the research method) satisfy the operator's manual minimum octane rating of 93 research method or not?

When you say high compression you have to use the right context, the C263 was "high compression" compared to the 7.5:1 (or less) compression of the early 50s, but no where near what people consider "high compression" for a modern engine - or even an old engine.

The nonLP C263 runs about 8:1 compression well within the operating range of 87 octane. An LP head C263 runs 8.8:1 compression. For comparison the 300 six engine in my 1966 Ford runs 8.9:1 compression on regular.

Don, looks like this gas issue has been beat around pretty good, but I never did see a direct answer to your direct question. So I'm gonna take a stab at it.
First a disclaimer: Although I have a couple of the six cylinder IH gas tractors, I haven't had them long enough to tell anything definitively.
That being said(and I too have read the operators manuals describing the need for 93 octane Research Method) I agree with your calculations that the 89 octane at the pump would equate to 93 octane Research Method. Don't know if anyone else out there agrees, but that is my take on it. Guess I'll eventually find out; I plan on running them.
Maybe somebody else will give their thought on the issue.

My understanding is that the M rating in the US has to be a minimum of 82. Since the R+M/2=89 you have two figures and can easily solve for the third, or the R rating:

(R+M)/2=89
R+82=89*2
R+82=178
R=178-82
R=96

Thus it appears that by the research method the octane of 89 octane is 96, or more than adequate for the 706. The research method alone is no longer used in the US and it is not sold that way in any part of the US. So I see no problem with 89 octane gas. If you do the same calculation for 87 octane (unleaded regular) gas the research method is 92, perhaps borderline for a 706 in good condition, possibly harmful if the engine has a lot of carbon in it.

Yes! the voice of reason, Well done. A

i don't want to incure the wrath of the tractor vet but i have a couple 706 gas tractors that i put c-301 combine motors in and i have never used anything but 87 gas. i have another 706 to switch engines in this winter and the 715 that gave it's life for me to do this was a neighbors' that farms around 800 acres and used several 715's to do their combining with and they have never used anything but the cheapest gas [87] and no engine works harder than a combine engine. they never had a minutes trouble with the engines, except a couple years ago the one blew a spark plug porcelin out of the head.

(quoted from post at 07:06:22 10/19/11) A couple of weeks ago, I got some recommendations on this site that I should use a minimum of 93 octane gas in my 656 farmall. I had been using mid grade (89 octane rating). My operator's manual says to use fuel with a minimum of 93 octane, research method.

I looked up some information on octane ratings and it said that the research method was approximately 8 to 10 points higher than the motor method. The ratings at the pump are an average of the R & M numbers.

So, if I assume that the R method is only 8 points higher than the M method, then to get an average value of 89 octane, the M number would be 85 and the R number would be 93.

Therefore, isn't the 89 average octane sufficient to use in my tractor? (since it means that the R number is at least 93)

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The way an engine runs is mostly a function of the heat value present in the fuel. BTU (Bristish Thermal Units is the measure). It is more commonly called the heat of combustion. Heck these old tractors have run on some real garbage over the years. The original Farmals ran on a middle distillate and that octane varied by as much as 10 numbers. The first octane numbers were run only on a RO engine , the MO engine didn't even exist back then. Ethanol has a low heat of cmbustion and doesn't run as well as regular gasolines will. It has a higher octane value, but that octane doesn't help performance.

(fuelsandlubestechnologies.org)

What the TractorVet tells you is true, EXCEPT......... he never takes into account that the new way of rating octane is R+M/2. Therefore, what is 87 octane today would be about 91 octane rating when your tractor was built. Today's 89 octane would be about equal to 93 rating when your tractor was built. Mike

With all the talk and disagreement about octane ratings and their use, has any one ever put a detonation sensor on one of these engines to help determine if we are having detonation or not. I certainly cannot hear any but my ears don't hear any high frequency at all . Others hear the old auto engines ping and I don't. Just seems to me we could tune that engine under full load for the fuel we are using by varying the total spark advance with in limits of course. It doesn't take very much increase in compression ratios and design of combustion chamber to alter the needed advance. I see guys running 40 degree advance on a M farmall with gasoline head and fire crater pistons. It was supposed to be 22 degrees with 93 octane fuel. I hear of guys pulling their engines that are rated at 1800 rpm down to 1200 rpm which has to drive that combustion chamber up the wall unless he had tuned his distributor for proper advance at that speed.

You're ASSUMING the 89 octane has a Research Method rating of 93.

The difference between Research and Motor methods is TYPICALLY 8-10 points, BUT it could be more, OR it could be less.

89 octane... What if the difference is only 4 points on this batch? Now you're running 91 octane (Research Method) fuel in the tractor and risking damage from excessive detonation/pinging.

The manual says AT LEAST 93 octane by the research method. IIRC, the octane rating on "regular" fuel was 95 using the research method in the heyday of these tractors.

Only 93 octane premium fuel can be guaranteed to have AT LEAST 93 octane by the research method.

Looks like everyone should use what they want to since there's no agreement. Another Factor besides octane is operators. Some can run anything and get years of use. Others can tear one up no matter what oil or fuel is in it.

mkirsch -- 93 octane by the (M+R)/2 method has closer to 104 octane by the research method -- extreme overkill. That fuel is meant for high compression modern cars, not tractors. To me the use of 93 octane by the (R+M)/2 method in low compession engines is ridiculous. If there is any doubt at all about 87 octane, then use 89 midgrade, which, as stated below has an R value of about 96.

My IH engine service manual, ISS-1040-1, last printed in 1968 says that the gas C221 and C263's have a compression ratio of 7.2:1, LP is not mentioned. The C291, also used in the 706 is not mentioned either, but the C301 which is sleeveless has a compression ration of 7.7:1. I don't know if the compression ratios for post 1968 engines were increased or not. The 460 is the largest tractor I have, the operators manual says to use 87 octane by the research method or 80 by the motor method. (R+M)/2 would be 83.5 octane. Not sure that that low octane is sold even at 5000 ft elevation or so, where the octane requirement is less.

Ya know Pete you and i both worked on I H tractors for a lot of years. around here we still have a bunch of older I h's still working for a living . I started seeing problems back in the early 80's with gas tractors. First it was a lot of plug fouling that looked somewhat like oil fouling but it was not . The one tractor that comes to mind that about drove me up the wall was a 641 ford that we did a complete major overhaul on with line bore decking of the block a total rebuild of crank and head both ends of the rods and OEM as per customer request parts wright from Canfield Tractor . When done it was run at the shop for a good 5-6 hours set to spec.'s and ran like new . I filled the tank with fuel out of my tank and it was running fine . Took the tractor out of the shop and parked it outside over night to see how it would start cold as it was in the teen's at that time Next morning i get to the shop and first thing was see IF the Ford would start , It started like summer and ran fine . Later that day i hauled it two miles to the customer and dropped it off and got paid for the job . Three days later i have one ticked off customer standing in the shop because his Ford would not start that morning . dropped everything and went to his mini Farm to see why we had a no start . YEp it would not start . It was 10 degrees and i am pulling plugs they were fouled . I put in a new set of Motor Crafts and it started but smoked but cleared out . Just figured he flooded it . He hauled is manure and parked it in the shed . Next day same thing fouled plugs , went back thru the carb to see if i screwed up . That was not it doubled checked everything . This went on for a week with a new set of different plugs . I could not figure out what was going on as it ran fine for him for two days then the problems started with it , he was not the only one with the same problems as i was at just about each of his neighbors with the same problems with the gas tractors of all colors . My buddy and i were there this one evening tryen to get this Ford running again and i said it has got to be your gas , so i went back to the shop and got ten gallon of what i was usen and drained what he was usen and put my ten in the ford. Ran fine FOR TWO DAYS and back to the same old thing when he put his FARM gas in it . And all he was doing was hauling two loads of manure a day from his massive herd of 12 cows he was milking with his mini spreader . So we took some of his gas put it in a bean can and threw a match to it , to the surprise of all standing there when the match went into the can that had been setting there while we tired to light the new SAFETY matches the match went out . To get this gas to burn we had to soak a old rag and light the rag then place it in the can of gas and it burned like a smudge pot . we tired the same with the gas i had and it flashed . we checked all that were having problems and it was the same . The difference was they were getting gas from the same supplier and i was not they were getting the cheap stuff where i was getting 93 . That spring the neighbor got a 766 gas and that was the first time we ran into the problem with it loosen power and trying to seize up . He was trying to plow with a set of 145 J D 4 x16 plows . When going down the hill it ran ok but turn and try to come back up the hill about half way she would start to miss , sometimes cough back and just plum die . When you would try and restart she was locked up . let it set for 10-15 min. she would restart and run fine so we thought . and the min. you tired to come UP the HILL in 4ht low with stick in high she would start to die and pull the crutch and get maybe 15-20 more feet and she would lock up . First we went thru the carb but found nothing . checked timing and it was dead on spec. went thru the valves they were a couple ths' out set them did change plugs as it did have D18's in it and dropped back to D15Y's , maybe a little help. but the problem was still there . at the time i had a late 706 same engine as Ronnie's 766 he was getting behind and i let him run my 706 with my fuel in it It was playen with them plows in first high . So we drained a half tank out and refilled with the 93 that i had and i took his 766 and hooked to my 710 4x16's and took it over ans started plowing with it i could pull a much heavier plow in 1st high with no loss of power or any sign of missing or bogging down or seizen . at the time we did not know the damage done by this but soon found out as the 766 was starten to suck oil .when that started it was not long before the first of many exhaust valves went to lunch and that was another problem that took awhile to get figured out and after a long talk with a man for Marion Ind. and seeing the Service bulletin that was about valve torchen and the use of oil that was not low ash . when we first pulled the head that is when we found the scoring of the sleeves and the damage to the top of the pistons above the top ring. Now that area above the top ring grove is .019-.020 smaller the the skirt are of the piston and according to the BOOK skirt to wall on new SHOULD be .0035 to .0045 clearance or RIBBON fit with x amount of pull on the blade . O Ronnies 766 w did a Clevit rebuild and just went the mic fit to each hole and did the head with the engine in chassy and new exhaust valves . Ronnie switched gas and oil and we had no more problems . I have lost track with out going back into records of the number of 706 gassers that i have bought from sales but there was not week that went by that i did not have atleast two setting on the lot to sell with one or two in the shop getting something done on them to make them ready to sell . My closest friends have one of the 706's that i bought and fixed up and they are in use each and everyday on dairy farms and one is just a play toy for the one guy . The one i sold to Bill R was the one that had the Org owners manual and that was when i fist saw the fuel rec. on them in black and white . But as for myself i have always run the hightest since i started driving . even back then where i worked we had GAS powered semi tractors and they were fed hightest 105 octane gas The B60 Mach that pulled the 50 Rogers lowboy got fed that way the old White Mustang got fed with it and the 549 I H 's got the same along with the 534 Fords. And so did my 56 Ford 292 T. Bird spec. with the dual quads and Isky 3/4 cam and until Eugen's 706 everything was fine Till he got that load of gas from a local fuel supplier that took not one BUT all 6 sleeves and pistons on a fresh engine with 35 hours on it . I stood behind my work but when i saw the new pistons looking like the ones i took out of Ronnies 766 i knew wright off what had happened and that is when we looked for a independent lab to test the gas and tell us for sure what was gong on . We found one in Columbus Ohio and for the small fee of 650 bucks they did just that . We DID NOT tell them who's gas it was or the octane , they told us and what was in the gas and what caused the melt down . Eugene still has a copy of the report and if i was as good on this magic box as i am fixen stuff and had a scanner i would put it on page by page . There are three or four of us that have made a living working on I H tractors and the rest of the guys on here just play with them and come running for answers but when you try and be nice they tell you you do not know what your talking about. And anymore i could really care less My feelings anymore about this is about as much a shooting a ground hog .

I would like to see you use the 93 octane in a 460 ford engine built back in 1970-71 you can not enver feed a 71 383 Mo Par set at the factory timing spec's with out it pigging on light acceleration So i am off my soap box since you are a far better engine builder then I.
And OH BTW The highest compression ratio that you can RUN ON THE 93 octane is a ( 9to 1 As per Clevit performance engineers.

Dave, I certainly agree with that. Sounds to me like most of the tractors TV worked on were abused. When I read about them pulling down and sputtering going up hill, I wonder if the operator knew he had a lower gear. Of the tractors I have driven, I tried not to let them get below PTO speed. Some people I knew wouldn't shift until it was a couple of hundred below that. May not hurt for a few feet, but not good if they run it like that too long. If no tach, if the tractor does not get up to RPM fast enough, I shifted down a gear.

Well Vet, you have sure been through wringer on those gas tractors. I remember how frustrating it was when those new 706 gas burners started eating valves, spark plugs etc. I once complained to our so called district mgr, he wrote his boss about us out here and we got a letter that dist mgr told him we had a poor attitude. That was the help we got. No one else was having any problems. Few weeks later I went to a week long session at Hickory Hills and the very first subject that was a common problem was, you guessed it. Poor engine performance on those gas burners. Burned valves, pistons, plugs etc. Wasn't long after that they introduced low ash oil, improved valves seals, different rings, oil pressure relief valves, and more. Not a lot of emphasis on gasoline octane ratings though, but they did of course have their min specs. Out here, like your tractors, they were doing their heavy work with them, not much just doodling around. Anyway, try not to let this forum get your blood pressure up. I know it isn't easy sometimes. Some have all the answers, I sure do not.

Tractor Vet, you are correct if you mean the 93 octane by the research method. The current (R+M)/2 93 octane is 100+ by the research method. I owned a 66 Plymouth 383 with 4 bbl carb. It ran on the mid grade at that time, don't remember the exact octane. Regular was too low, Super premium was not needed. That engine did not have a compression ratio as high as the Ford 390 or the GM 396. I traded that for a 1972 Chevy Monte Carlo with 454, unfortunately the first year GM dropped the compression ratio to 8:1 from 10.5:1 or so. It did not accelerate nearly as well as my 66 Plymonth, when the previous year the 396/454 would leave it in the dust. It also would ping on unleaded regular if I went from the 2800 ft altitude where I live now to the 500 ft or so where I grew up. Going to quit, this is not about tractors.

66 383 4 bbl mopar was 10 to 1 and way back then you were if you were running sunoco you COULD get by with 230 a 66 Ford 390 4bbl was also 10 to 1 a 70-71 429 SCJ was 11 to 1 and also a 460 was 11 to 1 . Ford offered two versions of the 390 in two bbl one was a reg fuel and it required 95 and the prem. fuel one required 100+ Now i have been around lots of engines and some that you may or may not have ever been around and back in the days of lets go fast if i had a dollar for every hour i spent on dyno's testing engines and changes we made i could enjoy retirement . Now i may not have and engineering degree but i did work around them mostly with ford and when i switched brands also Chrysler . and on this issue on the 93 MINIUM fuel requirement on the newer I H tractors you would have to see for your self what is going on , first off they are not the old slow turn engine that was a large bore and long stroke they are small bore short stroke and they now DO NOT have forged pistons that can get ride of the heat fast enough Believe me i had to get the gas tested that caused the second melt down and your thinking is fouled on this . I do have a lab report on the gas and the chemist went into great lengths on this as to why the 87 burns so much hotter then the 93 of today . Up till the death of the performance car era i had some really fast rides and the best one was my built 61 ford rag top with a 390 tri power that i built when i was 17 back then it was a 11.56 in a 1/4 and that one you COULD get by if you were light on the pedal with Sunoco 250 If it was the weekend it was the last click on the pump past 260 BUT i was running 13.5 to 1 with 72 CC heads . Like i said we ran all the old semi gas tractors on 105 back then to keep them running cooler and not detonate . when the new gas tractors come under a load it is not like what a car goes thru when ya mash the gas with a car you start a load off and it lightens as you gain speed . When a tractor engine comes under a load it increases till you reach the end of the field or the pull is over . The 87 or reg. of today is made for emissions and it runs way hotter and burns fast . Cars are now computer controlled and at the first tiny little ping the timing is layed back the injectors are told how much to squirt . with and old tractor engine ya got a mech . advance dist. a up draft carb and that is it when the flash happens the heat is much higher . that heat can not get away fast enough and the top of the CAST pistons start to swell . when you put a mic to a piston when building a engine you will find out that on the top above the top ring that it is .019 to .020 smaller then the skirt and when fitting said piston to each hole here again no two pistons are the same out of the box. So you mic. each and size each hole for that one piston that is going into that hole Myself on a C263-291 i like .004 skirt to wall clearance So now with that and the .019to .020 at the top YOU should have about .024 clearance Should be more then enough , NOT with the 87 that top of the piston will expand over that and guild to the sleeve With the 93 that we get at the pump this does not happen as it burns cooler and slower and longer , now like Don 656 said he did not see any horse power increase NO you will not see a huge H/P increase BUT if you had that tractor on a dyno you WOULD see a little a horse or two and IF you had a pyrometer on it you would see a drop in EGT . NOW the next thing here as to Compression ratio on them , you also have to stop and think how many times that head has been off that tractor because of burnt exhaust valves because of not using low ash oil on this i am dead serious as here again i have learned first hand and after a lot of talking to OLD I H wrenches one guy from Marion Ind.showed me the TSB on the valve burning problem . But just how many times has the head on that tractor had .007-.020 shaved off it . Each time the compression ratio goes up . How many of them old dist. are wore out and giving just a few degrees more then they should ?? Can you run a dist strobe ?? and rebuild and test a dist?? I can and i have been doing it since 1964 when i bought a brand new 1020 Sun Scope and a 505 strobe and went to the Sun school to learn how to do this. Wright now i have two S/MTA's that will not run on the 87 because of the plain 450 Gas head and the above 8500 foot pistons and they are both running over 90 H/P . Put them on the New Holland 355 Grinder mixer and feed corn to them off the drag and watch them work . But they will not do it on the 87 or the 89 . I do a darn good job of maken the old gas tractors run and have been doing this for many years . My one friend a old fellow jocky of mine i did a 706 narrow ft fast hitch gasser for him and at the dead weight pulls it was never beaten and had two rooms full of first places to back that up . I would extend and invitation to you to come and see for your self and i can show the end results of the cheaper gas in these engines. Our tractors aren't pretty but they do run and run well and if it means spending the extra 20 cents a gallon then this is what we do . We use around 5-600 gallon of gas each year for what we have in gas tractors . And around 1-1200 gallon on the diesel . we will not get into the cost of the injection pump problems with the new diesel fuel.

HAve someone scan and post your lab report! Youve said this before, and havent backed it up with proof you have it! Also, why do you continually make references to OTHER vehicles in your posts, they are not in question, the IH tractors are in qiestion, as well as the debate of old vs new gas octane ratings, which you seem to still be stuck in the 60s in your way of thinking, or sipping on your bottle once again. As I have told you before, I do have respect for your knowledge, and your obvious many years of experience, but I can not and will not agree with you on this, and Im sure others wont as well. I base that on MY experience with our 806. We ran pretty much everything on the cheapest stuff atthe store up the road, ran it hard, sometimes 16 - 18 hours a day, for years.The only thing we never touched on it was the engine, and it had abroud 3500 hours on it when we got it. EVERYTHING we had, except for a few diesels, ran on the cheapest gas, never a fuel related failure, so you tell me why everyone else blows pistons on cheap gas, and we didnt?

Here i can not answer your question on this as to why you get by on the cheap stuff I just know what has happened with what we have dealt with . Yea mmaybe i am stuck back in the sixty's . But that is when these tractors were made and when the mid seventy's came around that was the end of the gas powered tractors . And that was when they made changes in the gas . That was when we first started having problems with our pick ups mainly because the group that i ran with did not have bone stock engines in them. My 460 gas tractor was anything but stock and it was a fight with it . Yes the copy of this as you put it is out at the farm in Eugene's desk . Now as getting someone to scan it and get it on here will take someone smarter on the thing than myself and defiantly smarter on computer operation then Eugene.He does not even know how to turn one on much less use it . Now the guys that have been getting along on the cheap stuff this i do not understand, is it because they are still running the org. pistons that were forged or what ?? do i have all the answers Not by long shot as i am still learning . And also why is it that some people are so cheap that you would worry about fifty or sixty bucks a year more for gas. Since just one hole from Case I H the last time we had to buy one was a 176 bucks and change plus the head set and pan gskt. Our fuel supplier has see this Lab report and the one time his new man brought the wrong gas out by mistake because Matt told him Take a load of gas out to Eugene's he loaded 87 and filled the tank with 300 gal. and Eugene filled the 706 and went to grind feed when he was about half way thru grinding the corn she seized up and she locked up till it cooled down . Then it fired back up but had a rap in # 5 with light scoring in 2 3 6 . 5 was toast Pulled her down and took the piston into Matt and set it on his desk and got the look of oh Shut and he called the new driver in and asked him what gas he took out and he said why the 87 why cause you said take a Load out to Eugene's and i loaded the reg. And Matt said my mistake and payed for the repairs . I still have that piston setting here in the office . as to New gas verses old gas Ck's thinking on this is not correct and 89 IS not the same as the 93 or what ever he was tryen to get across. Even Clevit performance will tell you that with the 93 octane of today that when building and engine for Street use you MUST limit compression ratio to no more the 9to1 and there is a world of difference between a STREET engine then a engine that is pulling a load . And here again would Forged pistons be better over the Cast pistons that they are suppling now on the rebuild probably . Gas today is formulated for emission and newer engines run way hotter then back then . I could see the extra heat in my Massy 300 with the 225 slant 6 with pump 87 it was always over 200 degrees . First thought was bad gauge , installed a Stewart and Warner showed that she was running at 215-220 . Changed water pumps with more impellers No change . Pulled the rad and had it rodded out and cleaned and flowede it was good . Still ran hot . Changed fuel grade one morning because the little station out in the middle of nowhere was out of 87 and he only had 93 and back then it was only a few cents more . engine temp dropped back down to 190-to 195 . and back to the question of this Lab report we do have it and as to getting someone with a scanner to do this i will try . But you are more then welcome to come and look for your self at it and the extra parts first hand and even run one of the tractors Trust me i have nothing to hide and i am not hard to find.

Don 656, in order to see whether or not 89 octane has at least an R rating of 93 we have to know the M rating. My reading indicates that the US version has at least 82 octane, thus if my calculations are correct 89 octane gas by the average of R+M has an R rating of 96. The M value can be as high as 85 and still have an R value of 93. If M is as low as 80, the R value is then 98. In other words with an average octane of 89, as the M value increased, the R value decreases, and vice versa. The ONLY way to be absolutely sure is to see if your distributer can find out what the M value, or better what the R value is. But, IMO, there is no way that 89 octane based on the (R+M)/2 octane is NOT going to be suitable for IH 6 cylinders. Many say that 87 is ok, but I can see that depending on the condition of the engine it may be borderline. I will also say the the only 6 cylinder I have driven is a 460, the manual says it needs 80 by the motor method or 87 by the research method. I will agree with Tractor Vet that it depends on how heavily the engine has been modified, or how carboned up it is, but that is as far as the agreement goes. Also if it does not detonate it is ok. My ears are too far gone to hear that anymore. Without further data or absolute proof, which no one including me and Tractor Vet actually have, you simply have to decide for yourself. I have entered into this discussion, because all my life I have been told and have read that low compression engines do not need high octane gas. Tractor Vets comments are the exact opposite of that, and I simply do not agree.

That's a great theory CKNS, but not realistic.

Heck by that reasoning what if the motor method has 1 octane? Then the gas must have 187 octane by the research method, right? It ought to be super-extra-awesome for the high-compression IH gassers!

By that reasoning, 87 octane should be okay because if the motor method says it has 80 octane, it must have 94 by the research method.

It doesn't work that way.

You can't just pull numbers out of your butt and say "what if?"

The research and motor methods come up with pretty close numbers. 8-10 points difference is about all you would ever see.

So 89 octane would have 84 by the motor method and 94 by the research method.

I looked a long time for the Motor rating of 87 and 89 octane gas with no consistent luck. I did find that the Research method is "usually" about 4 points higher than the R+M/2 rating sometimes 5, meaning that by the R+M/2 rating 87 octane has 91 octane by the research method, 89 has 93, and 91 has 95. I did not specifically see 93 octane, but I suppose it is about 97. It doesn't really change my conclusions below that the compromise of 89 R+M/2 should be sufficient for IH 6 cylinder engines used in the 706-up but makes the 87 more borderline. It will vary by manufacturer and the part of the country where the gas is purchased. I am done with this.

(quoted from post at 12:55:23 10/20/11) You're ASSUMING the 89 octane has a Research Method rating of 93.

The difference between Research and Motor methods is TYPICALLY 8-10 points, BUT it could be more, OR it could be less.

89 octane... What if the difference is only 4 points on this batch? Now you're running 91 octane (Research Method) fuel in the tractor and risking damage from excessive detonation/pinging.

The manual says AT LEAST 93 octane by the research method. IIRC, the octane rating on "regular" fuel was 95 using the research method in the heyday of these tractors.

Only 93 octane premium fuel can be guaranteed to have AT LEAST 93 octane by the research method.

Click to expand...

Exactly.... which is why I wrote "ABOUT" 93. Good point, Mkirsch. Mike