(27-11-2018, 07:25 PM)Bob Culver Wrote: Unless finished in place all shells are made with an exaggerated clearance at the parting line although it may not be obvious.
Bob, surely you mean interference? (or 'crush' as it's known in the trade). The shells stand a few thou proud of their housing so they are forced firmly into it on assembly. It is this radial force (not the tabs) which prevents the bearing shells turning in service.
I think what Bob is referring to here is the fact that big end bearing shells aren't usually a uniform thickness, they are thinner near the split line, so will present an oval hole giving greater side clearance to the crankpin
Ah, I see. In that case he is quite right (sorry Bob).
(28-11-2018, 01:12 PM)Colin Wilks Wrote: I always steer clear of religion and politics, but as far as the white metalling goes I have my rods booked in with Ian Burlngham at Malton, so I think I'm in safe hands.
Zetomagtneto said "Check small ends for wear, as Bob Foreman says there is so little material it makes it difficult, or perhaps inadvisable to bush them". I think Bob was meaning it was inadvisable to address wear by machining the little ends oversize to fit oversize pins.
I am a bit foxed foxed here. I haven't got the engine out of the car yet so I haven't seen the rods, but being fully floating gudgeon pins I had imagined the little ends would be bushed anyway, and so any wear could be addressed by renewing the bushes, always assuming the rods are otherwise sound?
Colin, Nippy rod small ends are not bushed, you would have to machine them either way,to fit bushes, or oversize pins.
If worn You could try honing them to 13mm which is only .012” oversize and use 13mm pins.You would need to get the pistons remachines as well.To be honest if they are worn probably not worth the faff/risk of saving them
As you have not stripped the engine yet you might find they are fine.
(28-11-2018, 01:12 PM)Colin Wilks Wrote: I always steer clear of religion and politics, but as far as the white metalling goes I have my rods booked in with Ian Burlngham at Malton, so I think I'm in safe hands.
JEL Bearings had a three month lead time on re-metalling when I spoke to Ian a few months ago.
(28-11-2018, 01:12 PM)Colin Wilks Wrote: I always steer clear of religion and politics, but as far as the white metalling goes I have my rods booked in with Ian Burlngham at Malton, so I think I'm in safe hands.
JEL Bearings had a three month lead time on re-metalling when I spoke to Ian a few months ago.
Yes, I booked them in for Feb back in September. I don't think he needs to advertise!
(27-11-2018, 12:06 PM)Colin Wilks Wrote: the crud that inevitably circulates in a traditional splash fed set up. As I do not want to get into fitting an oil filter I have decided to stick with white metal.
CRUD...INEVITABLY!!!!
Surely, sir, you would thoroughly clean out your engine, including crank......then good quality fully synthesised multigrade oil to keep it that way and give minimum wear........we won't mention "Merlins magic additive" (as it has once been erroneously referred to) which I would never be without in any mechanical device.
(27-11-2018, 12:06 PM)Colin Wilks Wrote: the crud that inevitably circulates in a traditional splash fed set up. As I do not want to get into fitting an oil filter I have decided to stick with white metal.
CRUD...INEVITABLY!!!!
Surely, sir, you would thoroughly clean out your engine, including crank......then good quality fully synthesised multigrade oil to keep it that way and give minimum wear........we won't mention "Merlins magic additive" (as it has once been erroneously referred to) which I would never be without in any mechanical device.
Dennis
Hi Dennis,
I have a feeling that oil is another "religious" topic in A7 circles! I just do what Nick T tells me and use Millers' Vintage Millerol 30 and intend changing it at least annually. The logic of using a non detergent oil seems to be to allow specs of carbon or other detritus that is not caught by the gauze to fall out of suspension and lurk in the gunk at the bottom of the sump until this is cleaned out, which I intend doing every other oil change.
I have bought the oft recommended "Which Oil" by chemical engineer Richard Michell to try to understand the subject better. Once I've read it I may be able to argue with you!
The attached photo of the side of the tin seems to describe the Seven engine pretty well. The brand also has the inestimable advantage of coming from Yorkshire.
Hi Colin
All understood. Yes much difference of opinions often expressed......sadly sometimes from old fashioned ideas that "that is what was recommended by the car manufacturer" without thought that oil has come on a long way since those days. I too have done much research into the uses and qualities of the various types of oils and am sure you will probably have just as sore a head as I did at the end! But much enlightened.
I was referring to an additive that I use which does not alter the oil one uses but merely uses it to get carried around the engine/gearbox etc. I have the lab test report on this additive from SINTEF (google it and you will see they are a very large and important oil industry laboratory) showing it does what the additive claims as does figures from MIRA tests. In spite of these two august bodies findings the additive has been referred to by some as "magic of the wizard Merlin type".
I did actually venture across the border down to the former abode of M in Cornwall but unfortunately he was not at home so could not throw any enlightenment on why some thought it magic.
A filter really is a good idea as an addition.
Mention of oil steers this off on a tangent well thrashed before. API SB covered oils from 1930s to the cheapest in 1950s and beyond, when cars were often rebored at 40,000. (Perhaps the oil incorporates modern features but is insufficently detergent to qualify as SC or later)
The VW Beetle ran with harder than wm shells and no filter to the end.
In an era when it is difficult to find written materiol pitched at everyday level, and the Internet is a morass, Which Oil is about the best read available. But the writer is not a current oil development engineer/scientist. The vital topic of instant viscosity whilst under pressure and sheer is not even mentioned. Oil change periods adopted are ridiculously conservative.
Back on topic, I presume the shells sold for the 3 brg engines and Big Seven are forgiving white metal. But what are used for the replacement rods? When cr rose above about 7:1 in the 1950s wm proved inadequate in many engines (notably BMC 803cc)
