87 octane

Jerry Gilliam · Apr 1, 2011

Interesting article in Progressive Farmer in April 2011(this months) issue. Page 36. Ask the Mechanic, Steve Thompson) says to use 87 octane in these older motors as it will explode quicker. The article was based on a question concerning a 656 gas. That would mean it was a 263 engine. Just so happens I have one along with a 460 with a 221 engine. I've always used 87 with the exception of a few times and had good luck. I have read here several times that they must run on hi octane. He also says not to use octane booster as this will slow down burn, which you do not want. Now go figure.
JW

John T · Apr 1, 2011

Im an electrical engineer NOT a chemist or fuel person but as I understand it higher octane is purposely made harder to ignite so as to avoid pre ignition spark knocking in higher compression engines. I dont think you should use any higher then necessary octane to prevent pre ignition and if you go higher theres more chance of carbon and unspent fuel left over versus if you run lower octane thats easier to ignite and may result in a more complete burn.

In these old relatively low compression relatively low RPM tractor engines I SEE NO REASON TO RUN HIGH OCTANE FUEL as pre ignition spark knock IS NOT A PROBLEM so why use harder to ignite high octane fuel and perhaps end up with a less complete burn and left over nasties????????

Ya know what makes me angryyyyyy When I was a kid I remember big oil tellin all us bumpkins they had to raise gas prices due to the cost of ADDING extra lead (LEADED FUEL) to reduce pre ignition like Gulf No Knox etc..........BUT THEN years later they had to raise the price to REMOVE that nasty harmful lead???????? So which is it, did they ADD it (raised cost) or do they have to REMOVE it (raised cost)????

John T

sflem849 · Apr 1, 2011

That's pretty standard theory. The only positive from running high octane fuel is that premium is generally no ethanol so it has a longer shelf life.

Jerry Gilliam · Apr 1, 2011

The big mistake was to ever let those big oil giants merge. Of course they said it would bring cheaper gas prices. LOL
Looks like ATT has the same idea with its' active takeovers.
And look at GE. No taxes paid. We paid more taxes than GE. Now ain't that a hoot.
JW

Janicholson · Apr 1, 2011

Yes it does seem like paying for what they didn't give us. The anti knock control was still needed, and to do it required more expensive cracking, and additives (including ETOH) So they just for got to tell us what we were gettin in out shorts as we bent over. Jim

karl f · Apr 1, 2011

The fact is a 656 owners manual says "93 octane minimum, research method." I have heard the 560 or 706 etc. manuals say the same or similar things. The problem is today's gas is rated by the average of both octane rating methods (motor and research), so without the spec sheet of the fuel, you don't know what the research number really is.
Those 6 cyl IH gassers were built for use in tractors to the point of self destruction, which the higher octane helped slow because the pistons wouldn't overheat and score the liners. Tractor Vet and others have discussed this extensively in the archives.
I believe if you aren't working them to the max, 87 (R+M/2) is just fine. And anything in stock form pre 58 or so would be fine with even less of an octane rating.

karl f

Jerry Gilliam · Apr 1, 2011

What ever happened to the Vet?

Anonymous-0 · Apr 1, 2011

Yabbut, it's those excessive corporate taxes like GE is paying that drives our jobs overseas. So let's give these companies another bailout, and then another round of tax breaks.

[And then notice how the corporate CEO's are ROTFLTAO at the rubes who are buying their BS and who believe that it's the American worker who is the "enemy."]

560farm · Apr 1, 2011

If you only used it for parades and tractor rides 87 might be ok. If you work it under load better use 92/93, unless you want to swell pistons and score liners and use low ash 30wt if you don't want valve problems. I have seen it happen like tractor vet. Vet posts now and again on tales.

sflem849 · Apr 1, 2011

(quoted from post at 14:00:36 04/01/11) What ever happened to the Vet?

I think he is super trucking.

RustyR · Apr 1, 2011

I used to run low octane fuel in my 806 gasser plowing & discing full thottle and yes I did melt 4 of the 6 pistons. After a rebuild, I will only run 93 now.

mkirsch · Apr 2, 2011

If tractor vet were available he would tell you that premium fuel (92+ octane) is MANDATORY in the IH 6 cylinder engines at all times. That is what I've seen him say many many many times, and I've had him tell me the same thing personally.

The post-1958 6-cylinder engines are NOT "low-compression" like the pre-1958 4-cylinder engines. They are high compression and they will suffer from detonation when you work them on 87 octane fuel.

Allan from PA · Apr 2, 2011

Just for information, I have a 1945 HV that runs great but will not shut off with 87 octane gas. Was told to use 93 octane and it would stop doing that. I did and it works great. Am happy the way it is. Allan.

teddy52food · Apr 2, 2011

That means it is firing like a diesel under load too before the plug fires. Not good.

Rumplestiltskin · Apr 2, 2011

I don't want to get too far off topic, but your mention of CEOs brought up a rather sore point.

I work for GE. In February 2010, we all received an email that due to current business conditions, there would be no employee bonuses that year or in the foreseeable future. A quick check on the internet revealed that GE's CEO Jeff Immelt had pocketed $2 million worth of GE stock (at no charge to him, of course) about two weeks before the email.

CNKS · Apr 2, 2011

I don't call the 7.2:1 compression high. 460 operators manual says 87 octane research method or 80 octane motor method. R+M/2 = 83.5, meaning that the research rating of todays 87 octane by the R+M method is higher than that recommended by IH-The cutoff for regular gas used to be about 9:1, meaning you should use a higher octane rating. If IH 6 cylinder engines fry with today's octane rating, my guess is that something was wrong with the engines to begin with. With mine I'll never know, because I don't use it enough under heavy load. One other comment -- low octane alone is not the only thing that damages pistons. Most are probably just worn out, and some people like to blame the gas, which as far as I'm concerned is much better than it was 50 years ago.

CNKS · Apr 2, 2011

I did a little studying on octane numbers. The M used in calculations must be at least 82, therefore the R has to be 92 for R+M/2 to equal 87. (92+82)/2 = 87. Thus todays 87 octane gas is 92 octane by the research method or a full 5 points above the 87 required in my 460 Operators manual. Should be enough.

LenND · Apr 2, 2011

We farmed about a 1000 acres with two Ms and plowed just about all of it. Then went to one M and a 400. Then a gas 706 and a 656 . They all were run on plain old regular delivered by the bulk dealer. No special additives, The Vet and I had a little decussion about that. He same as called me a liar. I have 70 years of running IH and Case tractors and he may know alot . But that one time he proved himself wrong.

LenND · Apr 2, 2011

That should be sixty yaers running tractors not seventy. Sheeeesh!

CNKS · Apr 2, 2011

(quoted from post at 15:05:48 04/02/11) That should be sixty yaers running tractors not seventy. Sheeeesh!

Probably only feels like 70. It appears that people that work on tractors have to blame the problem with the engine on something, in this case gas. Basically it is impossible to prove. People like yourself who take care of their equipment, don't overload it, etc, probably have overhauls simply because of normal wear. Almost impossible to pinpoint a specific reason, although some repair people try.

87 octane

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