Farmall m - whats up?

north puller · Nov 17, 2012

atached is a graph showing the pto torque curve of 2 farmall super m motors. The bottom is a pure stock, somewhat worn out 264 inch super m. The top is a somewhat built up 281 inch motor with higher compression and a cam.

Can anyone tell me why the torque takes a dive the way it does in the circled area? What might be going on here?

The tractors were dynoed on the same dyno, the same day. A M&W slide chart was used to calculate HP, then the HP and PTO speed were used to calculate torque.

I dynoed 3 other tractors that day, (not farmalls)and no other tractor experienced this dive in torque at 400-450 pto rpm which makes me think that it is nothing to do with the dyno.

Any idea what might be going on with these super m motors?

Aaron SEIA · Nov 17, 2012

Just my SWAG but is it the way the Farmall gov is working?
AaronSEIA

Ed Carlsen · Nov 17, 2012

Just a thought carbs on farmalls frosting or was the same fuel used in the farmall tractors (high octain?)not enough compression to burn that fuel?

johns · Nov 17, 2012

I think the cam has the biggest effect on the torque curve and where it climbs and drops. Surprising it is in about the same range on both tractors.

Roger in Iowa · Nov 17, 2012

Sticky advance mechanism in distributor?

CLIFF S · Nov 18, 2012

My SMTA would Change like that too But it was the time the Gov Opened up all the way!

I Changed the Gov Spring to a Stiffer One and it Helped make the Gov Smoove Out and Gained about 2 Hp at 540 on the pto!

Cliff S

north puller · Nov 18, 2012

It is not the gov. For the sake of the dyno test, the 281 had a very stiff spring. Likely would give 2500 rpm or higher. I loaded the motor up at part throttle, then opened the throttle up all the way. I then baked off the dyno till rpm's cam up to 700 pto. I didn't want to let it go any higher and didn't feel the need as I run slower than that at a pull. The gov was for sure wide open all the way.

The dist in this tractor has a 40 deg plate in it - could it be something to do with ignition timing and a change in the advance at that rpm? Would a dist with a 30 deg or 25 deg plate be a better choice?

CLIFF S · Nov 18, 2012

The More Compression the Less timing advance to Loug well!

I would Try a Distubitor with Less Advance and make Shure it works Smoove on the Advance and not hanging up!

Cliff S

High Octane · Nov 18, 2012

north, use stiff advance springs, or lock it up all together like a mag. itll help.

Anonymous-0 · Nov 18, 2012

main thing is cams advanced to much. distributor needs advanced lockout and timed for initial timming . my two cents

north puller · Nov 19, 2012

How may motor rpm's will the tq curve shift with 1
deg change in cam timming?

Anonymous-0 · Nov 19, 2012

(quoted from post at 06:42:25 11/19/12) How may motor rpm's will the tq curve shift with 1
deg change in cam timming?

I wish it was that easy . A cam with a duration of 200 @50 should be maxed out by 3000 or a tic above when put in straight up but rod length etc is variables that change (general)characteristics .

Dodgeit · Nov 19, 2012

(quoted from post at 13:31:27 11/19/12)

(quoted from post at 06:42:25 11/19/12) How may motor rpm's will the tq curve shift with 1
deg change in cam timming?

Click to expand...

I wish it was that easy . A cam with a duration of 200 @50 should be maxed out by 3000 or a tic above when put in straight up but rod length etc is variables that change (general)characteristics .

Although it could be a timing issue. I have seen simalar results when a clutch is slipping. Especially since you mention pulling the throttle open from partial. My guess is clutch slipping.

Anonymous-0 · Nov 19, 2012

(quoted from post at 11:56:51 11/19/12)

(quoted from post at 13:31:27 11/19/12)

(quoted from post at 06:42:25 11/19/12) How may motor rpm's will the tq curve shift with 1
deg change in cam timming?

Click to expand...

I wish it was that easy . A cam with a duration of 200 @50 should be maxed out by 3000 or a tic above when put in straight up but rod length etc is variables that change (general)characteristics .

Click to expand...

Although it could be a timing issue. I have seen simalar results when a clutch is slipping. Especially since you mention pulling the throttle open from partial. My guess is clutch slipping.

True I would have thought that would be ruled in or out by the dyno not being able to pull engine rpms down.

Farmall m - whats up?

north puller

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Aaron SEIA

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Ed Carlsen

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johns

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Roger in Iowa

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CLIFF S

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north puller

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CLIFF S

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High Octane

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Anonymous-0

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north puller

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Anonymous-0

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Dodgeit

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Anonymous-0

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