I thought that only the higher hp gas tractors like the 706 required the higher octane. But I read a post a day or two ago saying that a 560 should also used the higher rating if you work it hard. I have a 300 that when it's on the baler sees a workout and an A with overbore sleeves and domed pistons that gets the snot worked out of it when the grass gets ahead of me. Should I use 89 or 93 octane instead of the 87? Just curious, in the grand scheme of things the extra 20€ or so for the 89 isn't that big of a deal.
- Thread starter Bkpigs
- Start date
Janicholson
Well-known Member
The topic is beaten to death.
If it spark knocks the fuel is too low in octane or the timing is too advanced, or the engine is fouled with deposits that glow when worked. Knock is the issue. 87 Octane (R+M/2)is good for these old tractors (even if the compression is at 135 or so) spark knock and preignition heats pistons and burns holes. Fuel today is more reliably what is on the pump. Run it. Ethanol is also just fine. Jim
If it spark knocks the fuel is too low in octane or the timing is too advanced, or the engine is fouled with deposits that glow when worked. Knock is the issue. 87 Octane (R+M/2)is good for these old tractors (even if the compression is at 135 or so) spark knock and preignition heats pistons and burns holes. Fuel today is more reliably what is on the pump. Run it. Ethanol is also just fine. Jim
Brendon-KS
Well-known Member
- Location
- Goessel, KS
Even the 706 had a compression ratio of only 7.6
to 1 which is very low by modern engine standards
so the need for octane is likewise low. High
octane fuel is needed only for very high
compression or turbocharged engines.
The manual for my 350 (7.0:1 ratio) specifies 86
octane Research Method or 80 octane Motor Method
which in today"s language would mean 83 (R+M)/2.
This is lower than the minimum octane fuel that is
available from the pump these days.
As was said, if you don"t hear pre-ignition
knocking with what you"re using now then running
higher octane fuel will accomplish nothing except
to provide more profit for the fuel company.
to 1 which is very low by modern engine standards
so the need for octane is likewise low. High
octane fuel is needed only for very high
compression or turbocharged engines.
The manual for my 350 (7.0:1 ratio) specifies 86
octane Research Method or 80 octane Motor Method
which in today"s language would mean 83 (R+M)/2.
This is lower than the minimum octane fuel that is
available from the pump these days.
As was said, if you don"t hear pre-ignition
knocking with what you"re using now then running
higher octane fuel will accomplish nothing except
to provide more profit for the fuel company.
mazemeister
Member
as for what gas to use, i'm not touching that with a 10 ft pole! Read the archives, the experts have weighed in.
But i will say that a 560, 706, 656 all used the same (maybe with minor differences) engine, the C263 and if you count the C291 and C301 which are just bigger displacement versions of the same thing you're talking everything from a 560 up to 856 in the gas. I forget what is in a 460 but i think it's just a sleeved down version for less cubes.
But i will say that a 560, 706, 656 all used the same (maybe with minor differences) engine, the C263 and if you count the C291 and C301 which are just bigger displacement versions of the same thing you're talking everything from a 560 up to 856 in the gas. I forget what is in a 460 but i think it's just a sleeved down version for less cubes.
Owen Aaland
Well-known Member
The C221 has the same bore as the C263, just a shorter stroke.
7.6 might not be high by today's standards, and today's engines have no issues running on 87 octane fuel even though their compression ratios are far higher, but you also have to keep in mind that 50 years ago is NOT today!
The 6-cylinder IH engine was designed in the 1950's and it was "bleeding edge" for the technology available at the time. It was being run right at the ragged edge of meltdown to produce the power it produced, and it was expected to do it 12 hours a day, 7 days a week, for years on end.
There was no electronic fuel injection, no computer to sense and adjust for fuel mixture and knock conditions.
The 6-cylinder IH engine was designed in the 1950's and it was "bleeding edge" for the technology available at the time. It was being run right at the ragged edge of meltdown to produce the power it produced, and it was expected to do it 12 hours a day, 7 days a week, for years on end.
There was no electronic fuel injection, no computer to sense and adjust for fuel mixture and knock conditions.
If I remember correctly no lead gas was used in all or most new cars beginning in 1972. (The first computers in cars were by GM in 1981 and had no effect on gas at that time). I think the cutoff for 87-(R+M)/2- was about 9.0:1. This is for cars, may or may not apply to tractors. But it seems to me anything up to 8.0 should be safe with 87 octane.
Anonymous-0
Well-known Member
I remember some farmers upping the compression ratio for more HP thus the need higher octane fuel.
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