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Allis B 112

briggs engine

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#1 mrmd OFFLINE  

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Posted July 24, 2016 - 12:21 PM

Just took the head off my Briggs 300421 to repair spark plug hoe(stripped threads). Noticed that there is some good scours on the hole. Engine ran and starts real good. Noticed the piston is an .020. It's my opinion that it was bored for the 020 and they just couldn't get all the scours out. My question is since it runs well and doesn't smoke should I leave well enough alone. How much can these blocks be bored out? All thoughts are appreciated. Thanks, Mike

#2 David Brown OFFLINE  

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Posted July 24, 2016 - 12:34 PM

Do you rely on the tractor for work or is it just a fun thing to have.  If it runs well and there's no smoke, I say if it ain't broke, don't fix it.

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#3 boyscout862 ONLINE  

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Posted July 24, 2016 - 01:11 PM

I would worry that dirt had gotten in and caused the scratches. That is why a good air cleaner is so important. I see it atleast once a year where the air filter was taken off and the engine run in a dust enviroment. The cylinders get very scratched up. It usually takes +0.020 over to clean the cylinder walls.

Clean the top of the piston and the valves. Clean the cylinder several times by spraying with WD40 or kerosene, then turn the crank until the piston comes up and goes down abit. Wipe the line of junk out of the top of the cylinder that was left when the piston went down. Do this several times until there is no loose dirt in the cylinder. Give it all a last wipe down with a cean cloth and then lightly oil it. Then put the head on with a new gasket. Change the oil. Use Marvel Mystery oil in your gas. Good Luck, Rick

Edited by boyscout862, July 24, 2016 - 01:14 PM.

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#4 EricFromPa ONLINE  



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Posted July 24, 2016 - 02:13 PM

If you plan on keeping it and mowing with it I would find another Block or Upgrade it to a 14,15 or 16hp briggs cast iron single.Or just use it till she's completely worn out then replace it.


Briggs made millions of the 16hp Cast iron block engines.You can find them on alot of commercial equipment with reasonable low hours pretty easily. 


If it's .020 over and still has wear then it needs bored again.Can't get a .040 or .050 over piston so just use it till you can find another block or engine.

#5 mrmd OFFLINE  

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Posted July 24, 2016 - 02:33 PM

Engine ran and started good before I did this. I have two 16s I pls and till with and another I mow with. This is kinda my utility version and not used much. Soon as new gasket gets here it,'ll go back together. Thanks foe the help.
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#6 petrj6 OFFLINE  

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Posted July 24, 2016 - 07:48 PM

    Before you do anything you should check parts availability, you can still get some stuff but I havnt seen any .030 over stuff for a very long time.