Guessing Total Miles

[Colin Morgan]

Hi,

How far did Sevens used to go in the old days between rebores, please?

The engine block on my Ruby is likely to be original (Feb '37) from the M number stamped on it.  Given it is currently sleeved and bored to -20 thou, would this suggest that the total mileage the car has travelled is about 5 rebores x 20K = 100K miles, or maybe a bit more?  The speedo currently reads 22K - perhaps this is suggesting that the total is about 120K?  (That is not a lot in 81 years, though.)

Colin

[Nick Turley]

Hi,

How far did Sevens used to go in the old days between rebores, please?

The engine block on my Ruby is likely to be original (Feb '37) from the M number stamped on it.  Given it is currently sleeved and bored to -20 thou, would this suggest that the total mileage the car has travelled is about 5 rebores x 20K = 100K miles, or maybe a bit more?  The speedo currently reads 22K - perhaps this is suggesting that the total is about 120K?  (That is not a lot in 81 years, though.)

Colin

Hi Colin
My erstwhile mentor (who taught me all) Les Sweet opened his garage in 1923 in Leeds and did many many Austin seven engines. He always told me that he expected them to do 60k or maybe slightly more if done correctly in fact he warranted his rebuilds for 30K !
Certainly my RP saloon (owned by me since 1968) engine had a rebuild in 1972 and did 63k before it's next one which was in 1991, since then it has had an easy life (due to not relying on it for all use) as this engine has only done 16k since. 
Now, like many of you I have several cars on the road (they all get used).
 To date it runs well currently, smoke free and good compression. 
So with current use all being well it should last my lifetime baring the unforeseen !
As a matter of interest I choose to use SAE 30 oil (none detergent). 
A fresh engine of mine gets gentle treatment of the first 1000 miles. I change the oil at 100 miles then four changes at 250 then 500 thereafter. 
I also remove the sump tray for cleaning the bottom out every three changes.
Oil seems cheap maintenance to me.
Quality of boring, quality of pistons and rings and correct fitting is paramount.
I learnt that lesson the hard way with some inferior parts I fitted some years ago.
If in doubt get expert advice would be my suggestion.
Proper cleaning of the crankcase and related parts is another essential - an area that many take short cuts with.
Above all else do not compromise, you risk doing it twice if you do.
Bearings are an area of poor performance there are some horrible cheap Chinese things not worth using.
Use RHP as original - they last.
Having good dynamic balancing is also worth doing for smoother running and longer life. 
Interestingly all the new cranks I have had required balancing despite the various suppliers saying they were balanced.
Hope that is of interest.

[Colin Morgan]

Hi

Thanks Nick.  If the rebores lasted 60K, this would put the mileage covered by a block with 5 rebores at 300K+.  This sounds high?  The car was less than three years old when the war started and petrol rationing went on until 1950.  If the car covered, say, 12K per year between 1937 and 1940 and then from 1950 to 1960, it would still only have covered 3 x 12K + 10 x 2.5K (based on a ration of 5 gallons a month) + 10 x 12K =  180K.  So it seem unlikely that many late Sevens did more than about 200K over the years, and the survivors generally less?

Colin

[Peter Naulls]

Our Ruby recorded 45 thousand miles in the first 17 years by which time it had very little compression and was badly in need of a rebore. Over the next 30 years it covered about another 48 thousand miles and smoked really badly before its second rebuild.

I imagine sporadic use (probrably off the road for the war years) poor quality oil and questionable maintenance would all be significant factors.

Peter.

[Colin Reed]

Hi Nick,
I think that your Assessment is spot on, Do it right first time.
To many times photos are posted when a job is being done and nothing has been cleaned not just on the engine,to my mind this unless on the side of the road repair is stupid.
How long does it take to clean something , it makes inspecting so much easily to do and No contamination on reassembly.
KEEP IT CLEAN

[Mike Costigan]

My grandfather bought this Big Seven in 1937; not brand new, it was the original Mann Egerton demonstrator, so may have had a few hundred miles, one thousand at the most, when he bought it. It was obviously laid up over the war years, and was also laid up every winter (4-5 months each year?). This photo was taken in 1969 when it had clocked up exactly 100,000 miles, every one in his hands!


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The valves were reground and the cylinders decarbonised each spring together with an annual oil change, but it was still on the original pistons and bores when it was sold in 1972. Sadly, in spite of having being kept so carefully, it seems to have subsequently vanished.

[Douglas Alderson]

Hi Colin

The logic sounds ok but have you considered that in the life of the car it may have one of the following done to it.

Clocked by a dealer or owner,
Engine swapped for a similar number,
Speedo replaced and not adjusted to original,
Car driven with a broken speedo cable not recording the miles.

[Colin Morgan]

Hi Douglas

Yes - I have driven it myself with the speedo not working a couple of times after cable failures.  Also, the speedo could have been swapped at any time.  The evidence that the block was originally in the car is based on the engine numbers at the time the car was built - again it is always possible that it was swapped later.  So, yes, speculation.  But what else is there to go on?  

Having been told above that cars might do up to 100K without a rebore - seems that the block may have been sleeved before it reached its 4th rebore at -60 thou for some reason?  But perhaps many cars were not so well cared for and needed more frequent attention?

Colin

[Bob Culver]

Cylinder wear is a very unreliable indicator of wear. At full operating temp wear is and was virtually nil. Many Sevens were used primarily for short runs and in cold climates would have run very cold. There seems to have been a major change in the 1950s presumably due API SB and better rated oils. Until then light cars were commonly rebored at low mileage. Even the likes of A40s were often reconditioned at 60,000 or so. The minimum overbore often not adopted; I suspect the first factory oversize was 1/32 (near .030). Reconditioners favour use of pistons they chanced to have in stock.
My RP was rebored about 1939 at 40,000 miles and , with both extensive main road and very short runs,  was a very worn .010 taper 60,000 later about 1957 (but not burning a lot of oil!). At 110,000 and much hill work there was some pitting of the pinion, possibly promoted by non optimum adjustment. Comparison with other old gearboxes seems to suggest these have done several times the mileage!
Mileage varies enormously car to car and with different owners. Few did regular long trips in Sevens but reasonably long daily commutes pile on the miles.  Here towns and cities were smaller and drivers who do 10,000 pa did 3,000.
It is also difficult to judge from general wear. Many older cars in later life were not regularly greased so wear through the spring bushes etc does not necessarily indicate vast mileage.
(Incidentally whilst many use expensive oils, change frequently, fit filters, etc presumably in pursuit of nil wear I have read of no one advocating  for a thermostat. Even Bradfords, which run hot anyway,  had these.

[Tony Press]

Hi,

How far did Sevens used to go in the old days between rebores, please?

The engine block on my Ruby is likely to be original (Feb '37) from the M number stamped on it.  Given it is currently sleeved and bored to -20 thou, would this suggest that the total mileage the car has travelled is about 5 rebores x 20K = 100K miles, or maybe a bit more?  The speedo currently reads 22K - perhaps this is suggesting that the total is about 120K?  (That is not a lot in 81 years, though.)

Colin

My three owner 1929 fabric saloon was fitted with the original light shaft coil engine until around 1971 and covered 78,000 miles in 51 years.

Unfortunately although the original owner kept some records there is no mention of rebore, but this could possibly have happened at around 60,000 miles.

For some unknown reason the original engine was removed at this time and replaced by an earlier magneto engine at 78,000 miles. 

The original engine had been carefully stored and was still with the car when I bought it from the second owner in 2015. When checked it was surprisingly in very good condition so the bores were honed and the original? pistons and rings refitted- unfortunately I didn't note the bore size, but  I believe the block was still the original.

The second owner only drove the car on car club events over his 40 odd years of ownership so the whole car would have only done some 80.000 miles in its 89 years.

Tony.