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Antique Tractor pulling with e85 help

Ethanol & Flex Fuel Tuning

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This is not efi related but im curious i pull a antique farmall model m tractor it has a 4 inch bore over haul kit with higher compression pistons compression ratio unknown but i try to run it on a 93 octane pump fuel when i take it too the pulls im really curious if drilling out the jets in the carb and trying to run it on say a 60% ethanol if it would give it a little more edge or does the compression really need to be up there for it to be worth it the head claims to have 200cc chambers i could not find and data for the domes on the pistons the classes i pull is farm stock so its basically stock rpm limit put it in first gear and run it till your out of traction or the engine stalls im just trying to get all i can get out of what i have to work with. Thanks in advance

Attached Files

Hello, I love this old school M my father has a vintage tractor museum and has many Farmalls in his collection, ethanol is a bit of a trial and error to see if it works better in an unknown engine as you have, generally, you would need to be above 12-1 to see benefits when used in a non-turbo application,

if you have spare jets measure them up and then drill out approx 20 percent the ignition timing will most likely not need to be changed but using a knock block and lambda sensor should be able to fine-tune it pretty good

Regards Ross

Ross Honnor thank you that tractor was more or less a parts tractor 3 years ago when i bought it that pic was just a few weeks ago after i put a paint job on it. I have a lm2 wide band havent bought a knock detection system yet but thats coming soon. im sure its no where close to 12:1 factory stats say like 5.5:1 so even with the bigger bore and the dome pistons id say its still making pretty low compression i might have access to a pto dyno need to ask if i can use it and run it on pump gas then try some ethanol and see im mostly looking for low end torque for when the weight box comes up on the sled and starts pulling the engine down wanna keep the fire lit as long as possible. Idle speed is around 400rpm and full throttle is around 1700rpm pretty wild when you compare that to the operating range of most cars.

a little nos works well too just saying LOL

Haha idk how well they would like that in a farm stock class

Is this the engine spec'- https://www.tractordata.com/farm-tractors/000/2/9/291-farmall-m-engine.html

Before getting carried away, I'd suggest checking the rules and regulations - if it's a "stock" class, there may be specific fuel rules and, TBH, I'm surprised you can even use such a big over-bore and higher compression pistons.

With the stock CR, I expected a side valve engine or some form, but it seems to be an overhead valve? Either way, that's a lot of chamber volume to take up - perhaps it'd be worth checking volumes of it all on the next rebuild.

It may seem a little strange, but if you're not running into any sort of detonation/pinking on 93, you may actually gain from using a lower octane fuel that better matches your engine, it's compression ratio, and it's camshaft timing. On that last, you may notice an improvement from advancing or retarding the camshaft a little, for a possible low or 'high' rpm gain in torque. If opening up the valve clearances a little improves the bottom end, that would suggest advancing may help.

Rather than changing fuel type, I expect you'd get more gain by optimising the fuelling for what you have, perhaps tuning from spark plug colour, and adjust the mechanical spark advance, if applicable, for best timing at full load at idle and at peak rpm.

Gord yes thats the data for my tractor in stock form they let the over bore in the stock class cause it would be hard to find one that old with the stock bore still in it and yes it is a over head valve engine. Yeah when i bought this tractor the head was cracked on cylinder 3&4 only showed 60psi on a guage 120psi on 1&2 so i gave it a light hone new rings and a new cylinder head this was before i became a vip member here. I would like to pull it apart a cc the domes and chambers to know what the actualy cr is maybe pull the cam and see how worn it is for all i know its a 72 year old camshaft i ran this tractor on e60 i mixed from a local gas station last week at a pull it did almost the same as it did on pump gas except i ran out of power in the 7500lbs class normally i run out of power in the 8500lbs class but when i did this i threw a larger venturi in it too and i think the lager venturi killed my low end torque so i might put the smaller venturi back in and try it again or just ditch the high ethanol all together but i had to try it it sure does put off a diffrent smell i set the carb with a lm2 wideband think i set it around 1 at low speed and around .90 .85 at the higher rpm. I appreciate your responses

Did any of the suggestions work for your problem with the dxf files?

Yes it did thank you Gord i forgot to click subscribe when i asked that