Welding of cylinder block

[YamahaV4]

I would like to heat the whole 2 stoke block in an electrical oven before the welding of a fracture. Does anyone know how high temperature can be used without ruining the small oil valves in the block? Are the valves completely made of metal?

If someone has a block that can not be used any more I would be interested in buying spare valves just in case... Please let me know. Please don't reply saying that the block can not be welded

[sandflyer]

I have some experience with welding these metals. I have welded on these outboard motors but never on the block itself. The aluminum / zinc rods work very well and are actually stronger that the base metal. I'm not quite sure why you want to heat the whole block. More important to slow the cooling process.
gene

[YamahaV4]

Hi. Thanks for your reply. I'm using a computer con*****ed double pulse machine with AlSi5 wire, not TIG so we have different welding processes. I mostly believe in wires that make a weld that has a lower yield strength than the base material. If the yield strength of the weld is greater than that of the base material it is usually more likely that the weld cracks in the heat affected zone (under fatique stress). Sorry this is so difficult for me to write about because English is not my language. I heat up the blocks to decrease the temperature gradient in the specific area. I have different welding programs in the computer for different temperatures. If the temperature gradient was zero, the structure would not change it's dimensions at all and there would not be left any tension in the cooling weld -> no cooling worries. But I don't try to say that I'm right and someone else is not.

But the original problem is still with me. I have to weld in a difficult area very near the valve and even without the pre heating the valve is going to heat up. Is it sold as a spare part or could someone cut that area off of some block and send it to me. (this whole problem started when a piece of the piston got off and was stucked between the connecting rod and the block. The block looks good on the outside but there is a hole between cylinders 1 and 2 on the inside)

Thanks

[slim]

are you talking about the little 90 degree valves on the sides of the cylinders? if so just heat the alum. around it and pull it out with vise grips while twisting.

[YamahaV4]

Are they valves or hose connections on the sides - they all seem to flow both ways...?

But I meant the valve inside the crankcase under the main bearing. If someone can get me a spare one please let me know.

[slim]

yeh you can replace them very easily. take a #6 screw and screw it into the valve and use pliers to pull it out. tap a new one in with a punch just a hair smaller then the hole itself. they arent pricey.

[YamahaV4]

Slim, thanks. I started to write about this without ever having a look at the cylinder block's spare part list. And there it sits - a valve for 4 dollars. I thought for some reason that it's not sold separately. How can I be this stupid...

Thanks again...