Welding Tips and Tricks

I have some old Harley panhead rocker arm blocks.These are two piece bearings for the rocker arm.The top being brass and the bottom cast. The fit is gone and I would like to rebuild them if possible.The question is what do I use? I'm thinking silicon bronze might work but I have never used it. I only need a couple of thousandth and will machine the fit. What do you think?
Thanks, Ron

I do machine work & welding & my first thoughts are a few thou is not much to build up & machine back - may start getting inclusions or have trouble machining that near the weld / parent metal transition - is it possible to bore over size to allow taking up the slack with a bush or bore oversize to allow more depth of buildup to be sure of machining a good surface ?

Thanks Noddy, these parts are halved and carry a shaft at about 13/16" and there are no parts that I know of that are oversized. It would be great if there were O.S. shafts and I really don't know why, it would be a reasonable and practical.

Anyway, for now I have to do it this way.

OK - I've not seen your exact engine part but speaking in general if you have the facility to machine then if there is sufficient material bore the half blocks out round & bigger then machine an interim bush to the original shaft size to take up the difference - I never heard of oversized rocker shafts either - they are also normally very hard so not easy to replicate - if you need to build the brass half as well as the cast steel you cannot use bronze / tig but this will work fine on the cast - I would personally not try tig at all on something like this if I had to build it up I would oxy / acet braze it - never failed me yet - if this is a common problem on older Harley's then maybe ask around on a Harley forum to see what other solutions people are using ? though I bet if you can wait till others here catch up & respond there are bound to be some fellow tractor owners ! - however you tackle it best of luck & hope you succeed.

I can build them up with braze, silicon bronze or 70 wire, what I am concerned with is what is a better bearing surface.

Many rockers have / had brass bushes in so I would say braze should work fine as long as everything is cleaned / fluxed & it takes well - the silicon bronze will puddle with the base metal so machining back to only a few though depth will leave a random blend of steel / bronze that will likely be inconsistent & not that good a bearing surface - ER70 should work if you want to keep with the original design of steel - hopefully some else is going to chime in on this as schedules allow maybe with more insight.

Thanks Noddy, good reasoning.I was apprehensive about using the ER70 when the base was steel already,but cast I think,I will give the nod to the ER70.Thanks

contact this guy http://tatromachine.blogspot.com/


he has a lot of weld repair videos on YouTube as well

The recommended way to fix this problem is to split the journal and sand each face on a flat surface and ream to size. I had some that were as much as .010 sloppy,fit is a about a.001. I ended up chucking them in my lathe took a light cut and ran a 7/8" reamer through the journal. Which is the correct way to do it.

When I asked the pro's if there were ever OS shafts made for this, I was treated to a free lesson on how to do it correctly.I guess there really is such a thing as a stupid question!

Glad you have it sorted - I don't think it was a dumb question - some engine parts are available in over / under size to take up wear - trying to build that little up & machine back was not really viable but you have now achieved a good result - I'm not sure how easy it is these days to buy but faced with worn bearing fit surfaces such as yours on obsolete engines we often would bore a little oversize to restore round then tin & white metal the cleaned surface & ream & / or hand scrape them to fit.