Timing a farmall 123 engei

1946 BN IHC · May 19, 2018

I have started and tried to time by sound on this farmall 123 engine. This is the first time in doing so. Is there any other information that my mechanics mauel doesen't give me that would be of benifit to securing proper timing of this rebuilt engine? That would make it run to the best it can.
Thank you for any assistant you may give to me.
Wm.

Janicholson · May 19, 2018

The timing mark for TDC is on the flywheel (tractor application) the hole used to see the mark is on the bottom center of the bell housing. The mark is usually very hard to see. Set number one piston on TDC, (Turning by hand till pressure is felt coming out of #1 plug hole, then with a plastic soda straw stuck in the spark plug hole, turn it slowly through the highest the straw moves while looking at the Flywheel. Clean the edge of the wheel to locate the mark, and paint it white. This TDC location is the static timing point, and should be where the points break when the engine is being cranked with the hand crank, or starter. This also places the centrifugal advance in the correct location for running at operating speeds. Setting the advance earlier is possible if very careful to not cause it to try to spin backwards against the starter, or the hand crank which will hurt someone. Make sure the advance system is working using a timing light to see it advance as the throttle is opened from idle. The advance system is located behind the breaker plate and not easily accessed. Jim

jeffcat · May 19, 2018

You sure make a good instructor on that one. I was just going to add that my 300U distributer has a tiny little tick mark in the edge about the two o'clock position. That is where the center of the rotor blade should be when firing #1 cylinder. Another way to get TDC that I have used. Take your air gun, turn the pressure down to a few pounds. Gently blow it into #1 hole as you slowly turn the crank handle. If the valves are open you will hear the air from the carb or the oil. Bath air cleaner. When the piston is comming up to TDC it almost sounds like a Slide whistle. You can get amazingly close.

gene bender · May 20, 2018

with a lite when the plug is out you can see when the piston is at the top

Roger in Wisconsin · May 20, 2018

I tried to find that Mark on the flywheel, about an hour later I gave up and used compression gauge and listened for the magneto snap.

1946 BN IHC · May 20, 2018

Thank you Gene,Jim, Roge and Jeff for all your information. Even though I have the engine running reasonably from idle to full throttel I just need to make certain all is in optomum condition before I start to put this old " raskel" to work haling loads, thus the question of making certain of best timming for optomum "performance" so that I am not out and burn a valve or somthing.
Thank you again I will check out all as has been writen and appy it.
Wm.

BarnyardEngineering · May 20, 2018

On a low compression engine like that, unless you are absolutely pulling its guts out for hours and hours, it's not going to burn a valve.

Oh, and you can SEE the piston come up on TDC by simply looking down the spark plug hole on a 113/123/135/153 engine. Just shine a light down in there.

teddy52food · May 20, 2018

Just to add to Jim's reply, the mark is in line with a bolt that holds the pressure plate on. Clean the spot in line with the bolt when you think it is close & you will find it. I have never found a flywheel yet that didn't have it.

David G · May 20, 2018

Easy to time by ear, loosen distributor so you can move it by hand, move back and forth slowly until the engine is at fastest RPM, then go to ideal, if loping back off timing a little until that stops. I have not timed a tractor by light in years.

Timing a farmall 123 engei

1946 BN IHC

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Janicholson

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jeffcat

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gene bender

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Roger in Wisconsin

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1946 BN IHC

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BarnyardEngineering

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teddy52food

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David G

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