rpm through the years

sald

Member
I just wanted to know (no plan on changing) about farmall A RPM settings through it's years of production.
High no load-1540 to achieve 1400 under load as per manual. Did they up the rpm without changing anything to increase HP later? I am scared to blow up the engine and was curious as to how high it can really go and not bomb.
 
The 'grand daddy' of all Jd 2 Cyl.(modle D) was a whopping 800 rpm. The last 2 cylinders wound up to almost 1200. The f12 was 1400,the F14 increased to 1600. The D282 in the 560 was 1800,in the 706 it increased to 2100.The 282 in the 660 wound up tp 2500.the dt436 in the 66 series was 2600.Tractor pullers often wind em up to several thousand.So IMHO,you can safely wind one up a couple hundred rpm without hurting anything.
 

Can't remember off hand the rated RPM of a Farmall H, but the same engine in a W4, I4 etc. has a higher rated RPM. I think the rated RPM of any engine was determined more by the application and what was needed to get the performance desired. Ground speed, etc.
 
H & SH were 1650 full load and 1795 no load. 300 & 350 were 1750 full load, the International 300/350's
were 2000 full load and 2100-2200 no load. But they make so much torque down low really no reason to run
them that fast. Torque peak of H/SH around 750-775 rpm. M/SM around 650-700.
 
Unrelated, years ago I modified the throttle linkage on a W-30 so we could get a little extra belt speed on the threshing machine,
a little more rpm plowing. One IH collector noticed it was running faster on the threshing machine at the show and told me the rod
bearing dip oil system was not designed for that speed, said they wouldn't oil properly.
I told him I would check the rod bearings that winter, never did. There might be something to that, I don't know.
 
Engine RPM has several ingredients for more power, and less life.
The first is that the A engine (and all small IH including gas H and M) have 3 main bearings. This places 1 and 2 between bearings with no support between them. The same for 3 and 4. Fine and dandy for ever at the rated RPM and displacement.
The second is that there are no balance weights on the crank, 2 up 2 down every revolution smooth kinda depends on equal weighted pistons and rods, and staying pretty slow.
The third is that the increase in rpm increases the effective displacement,i.e. 10% more RPM= 10% more firing strokes per minute. But the carb, valve size, cam profile, and timing are all designed around the working load RPM as designed for PTO, or plowing, and the rpm will likely drop to that RPM when loaded because that is where the torque is found.
The real value of any speed increase (to lets say 2500) depends on new intake, new Cam profile/timing, new ignition timing, and maybe bigger valves. Making power for farming means getting a bigger tractor. Getting more power in a tractor pull means getting a bigger wallet. Jim
 
My take is that more RPM is more combustion events per time, more heat flow, and where heat concentrates in an IC engine is where there are likely to be problems. Which are typically bathed by combustion itself or exhaust.

A cooling system in top shape would be another plus.
 
When I was setting the governor it revved up to 1650 1700 for a few seconds and I got panicked. It is at 1530 to 1540 now. I just wanted to know if my fears were unwarranted is all.
 
(quoted from post at 13:05:26 09/11/18) When I was setting the governor it revved up to 1650 1700 for a few seconds and I got panicked. It is at 1530 to 1540 now. I just wanted to know if my fears were unwarranted is all.

150 RPMs over rated speed for a few seconds is not going to hurt anything. You could probably even set the governor for 1650 RPMs and still have a long engine life.

My 1940 M was running kind of slow when I first brought it home. I verified my opinion by checking the speed at the PTO shaft. Wide open throttle would give only about 500 RPMs at the PTO. I adjusted the governor to give 600 RPMs. I don't know the engine speed after the adjustment, but the tractor just felt a lot better.
 
The W-4 has the SAME rated engine speed as the Farmall H (1650 rpm). The group of tractors that I am aware of with different rated speeds were the F-12 (1400 rpm), W-12 (1700 rpm) and the O-12/Fairway-12 (2000 rpm).
 
I don't know about the rods, but that long crank with no center support definitely would make me nervous trying to spin very fast. Dad said they broke 2 cranks on F-20s back in the day trying to run 200 rpm above normal. I don't know how long they lasted but apparently there is not a lot of room for error on rpm on the splash lube engines.
 
My father had a Super A he bought when it was 10 years old from the original owner. It looked and ran like new but over the years he loaded up the engine with carbon from cultivating all day with it at idle speed. I used to hold the governor open and run it until the carbon got burning and blew out the muffler in the form of sparks. Never seemed to affect the engine in any way. Still ran good and used no oil when I sold it after his passing in 1991.
 

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