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Old 01-30-2016, 03:17 PM
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Default precision hardfacing?

I ended up purchashing a set of 4valve heads for the 77 BMW R100RS..

Rather rare setup..

It looks like somebody got in there and heated up the contact surface of the push rod pad and this has allowed for the tappet to mush the face of it..

I have 2 options.. I can hardface it with a tig or pull the bearings and do a complete re-hardening of the seat/contact area..

The first idea would be the easiest and least expensive time wise..

The second one would mean having to remove the bearings (28.00 eachX4) then heat and quench the faces.. This is my least favorite method but could pull it off in a pinch..

So my question is where do I find some fine mesh tig hard facing rod?
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Old 01-30-2016, 03:57 PM
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I would think that some of the 1/16" tool steel welding rods could be used by knocking off the flux. Have you done a hardness check on the pad next to it?
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Old 01-30-2016, 04:32 PM
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Ya what he said. I would check the hardness of the neighbor with a punch and then go from there as to what rod to use
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Old 01-30-2016, 04:46 PM
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Jen what I see looks like fairly typical wear. Are you sure enough is eroded to warrant welding? I might be inclined to buff the rough spots smooth and use them as long as your not out of adjustment.

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Old 01-30-2016, 04:46 PM
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In days gone by we used to play around with a few repairs like this--results were varied at best. Metallurgy is critical--you need to know (or determine) the exact parent material you're dealing with and match your filler/build-up rod to it. Get it too hard and it'll take out the tappets pretty quick; too soft and it won't last long at all. We had one case where the build-up flaked off and ended up taking out the engine bearings themselves.

Personally I'd replace parts rather than weld it but if you wanna go for it Gerry's on the right track--you need something more along the line of a tool steel rather than a hard-surfacing rod. The latter will be too brittle, in my view. Both of your approaches require that you get the heat treat and the pad profile just right or you're going to have issues...
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Old 01-30-2016, 05:38 PM
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One of my former jobs we used to do a lot of tig welding of hardened tool steels. A2, M2, and H13 were the common ones we used. There were tig rods fairly readily available, but I don't know what suppliers were used.

When we were welding this stuff, the weld would be as hard, or slightly harder than the base metal, but as mentioned, it depends a lot on the base metal and it's properties. If it was surface hardened material instead of 'through' hardened, then there's no guarantees, as the filler and base mix in the puddle and the carbon content can then vary widely.

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Old 01-30-2016, 07:52 PM
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Well, As with any of this stuff. It's vintage and the guy who made this is dead..

So, its a crap shoot.. The surface that is worn or eroded by the tappets is pounded down you can see the grooving and the face is flatter vs convex vs the narrower one..

I do agree with making it to hard but the tappets are very hard or at least are supposed to be..

Think automotive cam shaft and lifter/cam followers.. They are very hard.. Upwards 60/62C.. The failure usually comes with lack of lube or bad break in do to bad manufacturing eating a lobe..

So, both the tappets have brinelling on there surfaces and I believe this is from oil break down via un even contact with the faces of the rockers.. very small contact patch.

In reality it's a bad design.. cam follower, push rod, tappet.. lots of places for slop..

A file will cut the back side of the rocker but not very easily..
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Jennifer

If I defend myself I am attacked.

My meaningless thoughts are showing me a meaningless world.

My attack thoughts are attacking my invulnerability.

I'd like to think of something smart, but I don't want to hurt myself.

My google+ page

DoALL 36"
Another Johnson model J Project
Lathe? Maybe..... 1958 SBL 13"
Yeti Esseti Aka running welder on 3phase.
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  #8  
Old 01-30-2016, 09:49 PM
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Try Crown Alloys in MI; great products and great customer service, they will also break packages if you only need a pound or two.

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Old 01-30-2016, 10:24 PM
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I would run that stuff by somebody that specializes in repairing rocker arms. You might try Kibblewhite precision machining, don't know if they do that but I would think that they might know somebody that does if they don't.

http://www.kpmi.us/
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Old 01-30-2016, 10:48 PM
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Quote:
Originally Posted by Shade Tree Welder View Post
Try Crown Alloys in MI; great products and great customer service, they will also break packages if you only need a pound or two.

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I have dealt with them and they are really helpful. I must have talked to there rep for a half hour about the welding process with one of their products.
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