Small Engines (Lawn Mowers, etc.): tecumseh 8hp flywheel fan and ignition timing?, john deere snowblower, plastic fan

Question
hi. i have an older John Deere Snowblower with a Tecumseh 8 hp (hm80?)model# that had a dead, under flywheel points magneto. After finding a used replacement, i went to reinstall the flywheel and found the attached plastic fan to be cracked. Altho i thought Duct tape would help hold it together, i was wrong. the thing flew into peices once i got it running hi speed. Where can i get just the plastic fan for this flywheel? How can i get the part number for this fan? Also, how critical IS the exact ignition timing? i have no way to measure the piston btdc, so i made an uneducated guess and at least it runs now. Is there any possible way to determine if i have it advanced enough to not overheat? would just a couple degrees from kick back be a safe place? i believe my specs call for .090 btdc and add the .010, making a total btdc of .100". i really dont wish to remove the head, and i dont have my calipers, or access to an offset depth guage. Thanks : )

Answer
Check out this link for timing:

http://www.cpdonline.com/692509.pdf

I have never had issues with the timing but have tools the factory Tecumseh tools to check it.  If the engine starts and stops well without overheating or backfiring your timing is fine.

Tecumseh parts link:

http://www.outdoordistributors.com/Tecumseh/Tecumsehpartslists.html

http://www.partstree.com/parts/?lc=tecumseh

Enter the model and spec number to find the parts list and then find the flywheel fan part number.

Let me know if you have trouble finding the part number.
Eric