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My Atom Minor build


911hillclimber
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It's a sorry tale of woe reading ths thread, I feel for you 911. If it was my build I would do what them clever people at Laser used to do and make them from barstock as those castings look ropey, even the best looking castings can have hard spots and blowholes bits of sand and other rubbish inside.

 

If you want to drill an accurate hole then spot drill first and then use a good quality stub drill, if you need to go deeper then swap for a longer drill after starting with the stub drill. Hold the drill in a collet chuck if possible as Jacobs type chucks are not always very accurate and any runout will make life more difficult.

 

It's amazing what you have done on that old lathe but if you use barstock mistakes are much cheeper!

 

 

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Posted (edited)
13 hours ago, Andy Stephenson said:

ED, surely that's an AM35 with the pink cylinder head. The 25 had a black cylinder head.

Well spotted  all of you 😳. Sorry your correct its a typo fat finger syndrom3 whaterver you call it; although all the bottom ends on the 25 and 35 are the same and can be swapped . That said if anyone does wsap parts between the two make sure they are from the same manufacture . IE the original wont swap over with the later models from Premier. 

Edited by Engine Doctor
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Posted (edited)

Thanks for the post, and you are right.

Still trying to work with what I have.

The drill jig I have made is surprisingly accurate (it seems) and is 6mm thick so acting as a drill guide, not that robust but good enough I hope to drill just the holes for this set of castings.

Really busy over the weekend, but will try to save the other castings with this rod if they prove to be compatible.

 

The drill wandered off when drilling, the drill would progress well initially then I hit hard 'stuff' and the drill (2mm dia) would simply ride to one side of the hard inclusion.

 

This was only in the end casting mounting bosses.

 

The rod supplied via ebay is Alubuild 300. The description reads it should do the job!

Edited by 911hillclimber
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Tried the 300 rod again today, nothing doing, must be the material of the casting?

 

Anyway, being that a none-starter, have screwed in some M3 screws with JB weld as an epoxy into the main case. This will fill the holes and bond the alum screws in place too (I hope). Easy to clean the machines faces with a light skim.

 

I then glued some of the same screws into the untapped holes in the front casting, again, easy to face the surfaces when set.

 

I have decided to machine the awkward rear cover/carb from the solid as a I have a nice alum bar the right size.

 

Although a mess, it could rescue the situation!

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I am in the process of trying to mend an OS 10 with a broken lug, with the same 300c rods Trying out various test pieces before comitting to the actual crankcase, has not been very succesful without the use of a special flux for Ali Soldering. So I can sympathise with your efforts. I am not sure how high I can heat the crankcase safely too.

Keith.

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Posted (edited)

Well, after a lot of faffing about finally got the front casting to match the one side of the main case, tapped and loctited in M3 steel studs, not screws.

 

The number of times I took that Sparey engine apart to get it all to clear and fit the threads in the 'aluminium' castings would have the threads worn or stripped.

 

Thus the nose is on and saved. That is 2/3rds of the £67 saved!

 

The rear will be a solid alum piece not the ropy casting as that is as good as scrap now.

 

 

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Edited by 911hillclimber
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