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Flywheel is shearing

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Please help Just did a compleate rebuild on my 14 horse briggs model 320421...after tearing it down twice because I was 180 degrees out on the timing...I finally have a VERY strong spark...and strong combustion and of course fuel...so after a week of tinkering in the garage after work I am a pretty happy guy but...and here is the part where I am stumped After I turn the key for ignition ( it fires immediately!) I get about 4 or 5 piston fires then the keyway on the flywheel shears I have replaced the keyway twice...getting pretty good pulling the engine!..but I am stumped...note I do not have the shaft that connects the engine to the hydrostat connected..don/t know if that is important or not, but thought I would mention it,,,and I am using ney keyways So,,,,, please help if you can! Again, thx..Dan

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quote:
Originally posted by BLT
What are you torquing the flywheel nut to? Doesn't sound like much
I know specs say 145 foot pounds but I do not have deepwell socket to use so I have been improvising

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BLT
You have to torque to 145 lbs. Just checked the book. If not not resonably close the nut will loosen and the flyheel will spin on the shaft. And god forbid but check the taper on the flywheel for any cracks and if there are any the wheel is on a self destruct course. BLT

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mr.jeffro
Torque spec is an absolute! There is no improvising. When I torqued my flywheel on I had to have my son and wife hold the engine assem just so I could torque that nut. Just like BLT says "check the flywheel taper for crack!" Also check the keyway slot. If the slot is chewed up and the nut not tight to spec this could cause your problem. Make certain that the flywheel does not bottom out on the crankshaft shoulder. The taper will insure a good tight fit. One more thing.. Do you disengage the starter when this happens or are you still cranking? Does it backfire? Timing? Trying to give you ideas.

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roma3112
hi all I WILL EMPHASISE TORQUE TORQUE TORQUE to specs i did a rebuild on my 300421 12hp and as you folks know pullung the engine on a 3000 series hb212 is a pain in the butt. Well being used to small hp engines most of my life i could get away with the ole " hand tight and 1/4 turn well needless to say i installed and pulled that engine on my 3112h AT least 3 times untill i went out bought a torque wrench and tigntend that sucker for all it was worth. Not ever rebuilding an older cast iron syncro-balanced engine i checked every thing from timing to counterweight timing ect, meanwhile it was mechanic headspace all the time, after i clamped that sucker down tigntend it so specs it worked like a dream. i would also reccomend a brigs key i have had a few of those "arnold non oem keys" give me trouble on customer machines. good luck john

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dlcentral
Use Briggs key torque up to fact specs.,If wheel has spun on shaft too much its a VERY good chance wheel is no longer any good,,it'll never stay tight,Sounds like someone ''monk-eyeed'' up the ign timing.Supoposed to fire at .020 or so before TDC.

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