|
Author |
Message |
billysugga
Joined: 01 Jan 2017 Posts: 55 Location: Carlisle
|
Posted: Sun Mar 19, 2017 3:08 pm Post subject: Adapting big end shells |
|
|
Has anyone any experience adapting shells from another engine to fit a conrod?
The bearings on my engine are obsolete and I cannot find anything with the same housing diameter.
The nearest is 0.2mm bigger but then the shell is too long(crush height needs reduced) and too wide also it has a big taper at the parting point.
Anyone done this kind of thing before?
Thanks Glynn _________________ Volvo Sugga ,Volvo Trygge
I just wish one was working! |
|
Back to top |
|
|
Uncle Alec
Joined: 14 Jan 2008 Posts: 734 Location: Manchester
|
Posted: Sun Mar 19, 2017 3:36 pm Post subject: |
|
|
I do it frequently with Riley RM conrods.
Identify the shell type best suited to your crankpin size, then check that it is larger than the OD of the big end housing. If you can find a shell at std that closely matched the o/d of your crankpin, you will have multiple opportunites for a subsequent regrind, though at our ages I am tempted to ask how long you forsee driving this car!
Check what limits endfloat on the original rods. On RMs the conrod has white metal cast on the side faces of the rod as well as the crankpin bearing surface.
If I am lucky the white metal adheres to the side faces after I have bored out teh housing to take the shells and I don't need to take remedial action. If I am unlucky I spot some mig weld onto the side faces of the rod and cap and reduce with a file until fore & aft play is acceptable; there is no fore & aft thrust so metal-to-metal contact causes no damage.
Much more to this that I can describe here, but PM me if you want a chat. |
|
Back to top |
|
|
peter scott
Joined: 18 Dec 2007 Posts: 7117 Location: Edinburgh
|
Posted: Sun Mar 19, 2017 3:41 pm Post subject: |
|
|
Hi Glynn,
I tried reducing the width of shells and changing the position of the spiggot.
I didn't need to reduce the diameter but I guess you could do this by locating the shell in the bearing cap and perhaps grinding it on an oil stone.
For the width reduction I created a mandrel then clamped the shells to it and parted them.
Peter
_________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
|
Back to top |
|
|
billysugga
Joined: 01 Jan 2017 Posts: 55 Location: Carlisle
|
Posted: Sun Mar 19, 2017 4:57 pm Post subject: |
|
|
Thanks for that Peter and Alec
I have some lister big end shells which are 0.2mm bigger on od they are very soft white metal. But also have some from a b20 which are 0.4mm bigger on od these are a harder alloy. In both cases I would have to reshape them to fit the rod and reduce crush height.
End float is just edge of rod to crank clearance.
What are your thoughts on type of white metal on a 50s engine?
And also diameter reduction? ( I tried mounting the b20 shell in the conrod but it doesn't sit correctly and becomes oval. The lister one is better, but this must be the closer to actual diameter the better)
I like your idea for width reduction Alec.
Glynn _________________ Volvo Sugga ,Volvo Trygge
I just wish one was working! |
|
Back to top |
|
|
Uncle Alec
Joined: 14 Jan 2008 Posts: 734 Location: Manchester
|
Posted: Sun Mar 19, 2017 5:05 pm Post subject: |
|
|
Lister used very soft lead/tin alloy, at least on my SR engines. Not good for high-revving engines.
What engine is this for? What crankpin mesurements? |
|
Back to top |
|
|
peter scott
Joined: 18 Dec 2007 Posts: 7117 Location: Edinburgh
|
Posted: Mon Mar 20, 2017 10:16 am Post subject: |
|
|
billysugga wrote: |
What are your thoughts on type of white metal on a 50s engine?
Glynn |
I think it would be best to try and locate bearings that have similar layer structure to the originals especially if this is a diesel engine.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
|
Back to top |
|
|
billysugga
Joined: 01 Jan 2017 Posts: 55 Location: Carlisle
|
Posted: Wed Mar 29, 2017 11:10 am Post subject: |
|
|
I have some bearings of bigger diameter and blued the backs and they seem to fit well on the backs. The crush height needs reducing. What is the best method of reducing the crush and checking it?
Thanks _________________ Volvo Sugga ,Volvo Trygge
I just wish one was working! |
|
Back to top |
|
|
|