Goodman

Member
Out of curiosity. What's about the minimum Rpm you can idle a 450 motor down to? I've got my Super A where it will just barely put along.
 
400rpm is pretty easy. maybe less if it is warmed up and the idle mix is tweaked while slowing it down. Jim
 
425 RPM idle is specs for 281 Fire Crater engine. Why would you want to go any lower RPM? I had an M and have a 450 both engines are 281 Fire Crater engines and if you let them idle very long they want to load up.
 

I've heard talk of getting an M to idle slow enough that you can count each cylinder as it fires. I can get my M to do that, but not for very long, and then it dies. No practical reason for making it idle that slow. It is just fun.
 
I rebuilt a stuck LUC JD combine engine. Carb was a ball of rust. I boiled it in lye water a couple times & blew it out. It will now idel down to where the impulse on the mag is tripping which I think is around 250 RPM.
 
Low idle speed is fine for a few minutes, preferably just before shut down, but , remember, the pistons get their oil from the throw off of the crank shaft rod journals. Never a good idea to let an engine run at low idle speeds for long length of time. Also, fuel mixture is normally richest at low idle speeds which again washes down the lubrication to pistons.
 
I have no problem with run on because I shut gas off and run it dry. I should state that I take my tractors to shows and pulls and run them dry so nobodies kids can start them by accident and it has now became a habit that I do it all the time.
 
good deal, that was the way you shut the John Deere D down is turn the gas off right at the dash. it had a rod right from the sediment bowl to the dash. i know the rpm on these ih's has to be low cause when u would come in from the field after hard working even after idling they still liked to run on.
 
The M had a 264 block in it that we over hauled to a 281 and it wanted to run on no matter how you adjusted carb. and timing was dead on. My IH dealer that I bought kit from rebuilt carb. & dist. That tractor I would shut the fuel off or put it into fifth gear and let the clutch out just about the time it came to a stop and would want to run on.
 

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