White Metal Bearings

[Lowbarn]

Please can anyone point to a thread that talks about refurbishing white metal conrod shell bearings?

Richard C.

[David Stepney]

I presume that you are talking about the big ends on a '31 two bearing engine. On these, the bearing metal is cast directly onto the conrods. This is specialist work and is best entrusted to  a specialist firm.

What has happened to your big ends?

[frequentflyer]

Pouring white metal is not difficult with a bit of knowledge and the right equipment. I have seen some fairly poor examples of work by professionals as well as DIYers. I have made several bearings for cars over the years and our steamer. My tips would be dont over heat the babbit material as some of the metals in the alloy can boil off and leave a less than designed bearing material if held too hot for too long and always preheat the parent parts. Most materials about 300C.
The best tip I learnt on the last bits I did having got the core stick in the previous job after sooting it up to make it non stick is to spray the core with a few coats of cheap red oxide primer. The paint burns off and the core comes out easily.

[Lowbarn]

My big ends are slightly loose David!
You are correct - ‘31 2 bearing 1 5/16” journals.
If I could figure out how to upload a 6 second video on here I could show you.
Noticed this after properly fixing the flywheel.
There is slight movement at TDC. Enough to make a clunking sound as the crankshaft is rocked.
I’m putting it back together in the morning and will see how fixing the flywheel has improved things.
If it still knocks badly I’ll start researching engine builders.
I’m not quite up to casting new bearings - yet!
I’m thinking I could look for a set of shell bearing conrods?
If I have to change the conrods I’ll have the whole engine refurbished.
Although it’s great entertainment fixing bits, I rather be driving it!

Richard C.

[Howard Wright]

Hi Richard

I am sorry for you. You haven’t had a lot of luck with the engine.

Before you put the engine back or start talking of engine building it might be a good idea to remove the sump and gauze and check the big ends from under the engine.  Slight knocks when turning the crank could be the valve train. It could also be just a case of tightening up the big end bolts (although this is unlikely).

I don’t think you can get shell bearings for 1 5/16 cranks. Whilst pouring a new white metal bearing might be doable, unless you have a lathe line boring the rods afterwards is a skilled job.

Good luck

Cheers

Howard

[David Stepney]

So far as I am aware, the later three bearing shell bearing conrods do not fit a two bearing engine , as they are not as wide as the two bearing rods and there will be too much end float. If the movement is only slight and the bearing surfaces are in good condition, it has been known to file the caps to take up the slack.

I would suggest before going much further that you invest in some Plastigage and discover just how much clearance you have between the rods and the crank. Also, check the crank pins for any taper and ovality with a micrometer or a set of precision verniers. You will need ones that measure to 1/1000 the of an inch. The cheapo ones only measure to 1/100th.

Do you have a copy of Doug Woodrow's Austin Seven repair manual?

[ppearson]

I think that 1 5/16" shell bearings are available from FW Thornton.

Hope this helps

[Malcolm Parker]

I wouldn't have thought that the use of shell bearings on a standard 2 brg crank was a good idea.  Flexing of the crank would surely knacker the shells very quickly.   I think you would also need an oil filter of some kind.   White metal bearings are much more forgiving.   It is something I would leave to an expert.

[Lowbarn]

Thanks for the advice. I have a very well thumbed Doug Woodrow David, extremely useful.

I test ran the car this afternoon and was quite impressed with my amateurish renovations.
No leaks and running much quieter. I decoked the head and emptied a barrow load of silt out of the tractor carb.

For those of you that answered my other thread, top marks for anyone who suggested loose flywheel - spot on!
The flywheel was very loose, it’s now very tight and virtually all the knocks and bangs have gone.

I think I’ll go along the plastigague route and research rebuilding the white metal bearings.
There is definitely movement in the bearings, but I don’t think it’s worsened in the last few weeks. There is no contamination of the oil yet.

Something I will need to watch closely.

Cheers,
Richard.

[David Stepney]

Provided the engine doesn't exhibit any weird noises and runs fairly sweetly, I would tend to leave things alone until something goes wrong.  The bottom end of a standard engine is quite long lived. My own car has done 112k miles (believed genuine) since new and is still running on its original crank and rods. The last time I had the engine to bits was two years ago, to fit new pistons and the bottom end looked to be in good condition then. I too had a slight amount of movement in the  big ends , which I corrected by judiciously filing the caps until I had about a thou radial clearance to make sure that the oil had somewhere to go.

I have done about 8K miles since then and all is still well.