Re-babbiting big end bearings

[Ian Williams]

These sketches come from Colin Reed, and depict the design of a jig he used when metalling rods, the idea is to make the jig quick release without the need to struggle with extremely hot nuts and bolts. The Rod and cap are metalled separately and Colin tells me the process was quite efficient and reduced the need to let the jig cool and then reheat it every time. 


  White metal Colin Reed 1.jpg (Size: 48.43 KB / Downloads: 475)

  White metal Colin Reed 2.jpg (Size: 42.84 KB / Downloads: 471)

[john williams]

Grieg, although it is not obvious from the pictures of my casting rig; there is sufficient clearance between the con rod/cap and the sides of the jig for a white metal coating of about 3/16 inch. Thus the need for the exhaust putty string to stop the white metal "running away". I have also sent Ruairidh a picture of "the Newton Big End Boring Bar" I doubt you will find another one, but it does show how the sides are machined, together with profiles of the cutters. So you could adapt a lathe jig to suit. Incidentally, I have made up right angled cutting tool from good quality Allen keys. They are hard enough to cut aluminum and white metal with no problems, and are ideal for the side thrust radia. John

Hello Chaps

Firstly thank you all for your valued input on this subject, I need to have the rods sorted in a short-ish space of time as I've offered the car to a friend to drive and the rods need to be sorted out rather urgently, so I'm now on a steep learning curve.....

The pictures of the jigs are invaluable, I too am curious about how to cast the white metal so as to get the thrust face on the side of the cap...... I've been considering how to do this and hold the rod in the dead centre, your collective jigs show this clearly, however I just can't see how the white metal will be able to 'cast' around the edges of the caps, hopefully the picture below will highlight this more clearly.

The rods are all that's stopping us from rebuilding the motor, we've bored out the oil pump and done the double oil jet conversion a-la Mike Forrest, so hopefully this shouldn't happen again. Quite a few of the tips and tricks in the 750 Bulletins from the '50's have been incorporated into this car and the supercharged sister car we're busy building...

Cheers
Greig

[Ian Williams]

Another picture from Colin Reed


  Colin Reed Jig.jpg (Size: 111.83 KB / Downloads: 360)

[Greig Smith]

Hello Chaps

Just a note to say that the jig concept is going forward tomorrow - drawing on all your collective wisdom this jig needs to be able to pour the shell and the side thrust faces in one pour - it also needs to have some sort of a quick release system so that one can swap out the rods and caps relatively quickly to do consecutive pours without loosing heat out of the mould, but more importantly so you don't have to handle a seriously hot mould 8 times in a row....

Will post some pictures of the results, my supremely talented Engineering friend Steven is already working on a basic concept - for some idea of his skill, pop over to the thread on our new Supercharged single seater and have a look at what he has done for us.

Now its just to find a bit more Babbitt material as I don't think we have quite enough...

Cheers
Greig

[Ian Williams]

Our white metalling project has been on the back burner for a while but today Marcus Ling came over and we successfully poured a couple of new big ends. Next job is machine them up and see if we have full depth metal with no inclusions, if that is successful we can get fully underway with production for several club cars. 

  DSC06556.JPG (Size: 208.08 KB / Downloads: 211)
  DSC06557.JPG (Size: 212.02 KB / Downloads: 211)

[Ruairidh Dunford]

Can you describe the tinning process you used please Ian?

[Ian Williams]

This is the part still under development Ruairidh, at this stage we are still experimenting, when we cleaned out the old metal from a few rods we had a couple with what appeared to be a perfectly tinned surface so to prove concept we used these. We do have tinning powder and pure tin so with luck Colin Reed will come up and show us how to correctly tin the rods that require this, I will report on that process in due course.

[Ruairidh Dunford]

Thank you.