Sheared Flywheel Key - Why?

buggyal

New Member
Looking for guidance. I recently rebuilt a FE350D AS27 in a CarryAll. The AS27 has adjustable rockers and tappets rather than hydraulic lifters. During the rebuild I discovered that the head was cracked. Replaced the head with one off of a AS11. See photo below. New rings, honed cylinder, lapped valves. I have run for just a few minutes. Upon starting it seemed to hesitate on the compression stroke. I am thinking that is is just a week starter. It ran and took it for a test drive. Drove for about 4 blocks. Shut it off to check everything over. All looked well. Stepped on the pedal it hiccuped and farted then nothing. Took it back to the shop and found that the flywheel key had sheared. Replaced the key and torqued the flywheel nut to 101 ftlb and put it together. Just started it up. Start up sounded normal. Drove 1.5 miles all sounded fairly normal. I did hear what I thought sounded like a little pre-ignition. Shut it off sat for about 5 minutes then started with a little hesitation on the compression stroke. Drove about .5 miles shut it off. Restarted no problem. Drove 2 blocks shut it off for 2 minutes and on restart it sheared the flywheel key. There is a small difference in the heads and the replacement (AS11) head is higher compression. Valves are set at .004 cold. looking for solutions.
 

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Jack M

New Member
Let me first say that I am not familiar with this engine.
My experience is with OB motors.
Is the crank shaft tapered?
If so you may need to lap it in, It is possible that the taper was thrown off when you removed the flywheel in the first place, especially if you had to hit it to get it to come free.
You may be able to check it with some Prussian Blue. Use valve lapping compound if you don't get a good full pattern. Be sure to clean thoroughly.
 

Nubs

Cartaholic - V.I.P.
Let me first say that I am not familiar with this engine.
My experience is with OB motors.
Is the crank shaft tapered?
If so you may need to lap it in, It is possible that the taper was thrown off when you removed the flywheel in the first place, especially if you had to hit it to get it to come free.
You may be able to check it with some Prussian Blue. Use valve lapping compound if you don't get a good full pattern. Be sure to clean thoroughly.
Agreed, I have run many 2 and 4 cycle engines with no flywheel key in order to adjust timing etc. All golf cart and snowmobiles engine run drive clutches with a taper and no key, all about matched surfaces and correct nut torque. Hair line cracks are very hard to see without magnafluxing.

Valve lapping compound:yes:
 

buggyal

New Member
Just got everything resolved.

Grabbed another flywheel and actually lapped the flywheel onto the crank. Cleaned everything up and torqued it back together. Started up several times and runs well.

Thanks for the help
 
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