I agree with hirschallan. If the problem is just a hole then there is a product called Devcon that is widely available that will do the trick. They have many different products but you are looking for is their aluminium putty. here's a link (no I don't work for them)
http://www.devcon.com/products/products.cfm?market=Maintenance%20%26%20Repair&family=Aluminum%20Putty%20%28F%29
I've seen the local OPE repair guy use it to fill a 2 inch hole in a Tecumseh block.
Cheers
This message was modified Feb 19, 2010 by GtWtNorth
https://t.me/pump_upp