I came across the following article in the Hooe's Old Car Club magazine, makes interesting reading and has a relevance to our bikes with professional engine rebuilds now over ?1000. Many bikes never being ridden after rebuilds and restoration have taken place.
ENGINE REBUILDS - ARE THEY WORTH IT? By David Bick
Now that vintage cars are so prized, like old cottages in the country, we often find the first thing that a new owner undertakes is a thorough restoration. And usually this involves a more or less total rebuild of the engine. For it is always assumed that a reconditioned unit must be better than an old one, and certainly no specialist firm out for business is likely to deter you. And regardless of the engine's true condition, it is not unknown for the client to be hood-winked into a total overhaul- crank grind, or re-metalling, re-bore, new pistons and all, on the basis that the job could not be guaranteed without one. Often, the results are disappointing, not to mention the cost. Oil consumption is a common pretext, and perhaps sundry miscellaneous noises in varying degree. But what is generally forgotten is that few vintage engines ran with a Rolls-Royce silence, nor ever approached modern engines as regards oil, most of which seem to use none at all. Indeed, such a goal would then have been considered not only unattainable, but undesirable. By present-day standards all vintage cars drank oil, and when the Rolls-Royce 20hp model came out in 1922, a consumption of 1,000 miles per gallon was considered ‘remarkably low’. And some sleeve-valve Daimlers could only manage 400! The standards of today are mainly due to tighter and more accurate clearances in the moving parts and better piston and ring design, all of which might be applied to rebuilt vintage machinery, but only at a price. For although you are likely to end up with a quiet engine, it will probably be sluggish, run hot at the least provocation and be heavy on petrol, to the extent that the extra cost of fuel easily outweighs the saving on oil. It is like driving with the brakes on, which in effect, is what it is. However, you will be told that - ‘all rebuilds are like this, and things will get much better on running-in, old boy’. But although this for long held true, the story is very different today. Largely due to improved oils, additives and filtration, engines virtually never wear out, and thus it follows that they do not run-in either, for running-in is simply a process of gradual wear. A man well known in the motor trade told me he had recently taken a BMW engine to pieces and the honing marks were still visible in the bores after 100,000 miles! No wonder Peter Lilley's 14/40 MG is nice and quiet;, but still tight after years of extensive motoring, and still is only doing 20 or 21mpg. (In this context, I am told that Castrol sell an old-fashioned ‘straight’ oil; which may be ideal for running-in, but no more details are to hand). Unlike their modern counterparts, vintage engines do not have the power to spare for the inevitable higher friction which results from tighter clearances. The late Freddie Dixon, the ace Riley tuner, said ‘take three thou off everything’ if you want performance and economy. If a Morris engine is free, with the plugs out you should be able to turn it over on the handle with one finger, even when stone cold. Some years ago when I rebuilt my 1929 Cowley UF 5170 (ex-Barraclough), bored out 70 thou to suit Renault pistons, I specified an extra 4 thou clearance in the bores. The engineer was horrified; but the car went splendidly from the start, often does 30mpg at 50 mph, and much to my surprise, uses very little oil. It is however, quite noisy when idling, but you can't have it all ways: The choice is yours!
ENGINE REBUILDS - ARE THEY WORTH IT? By David Bick
Now that vintage cars are so prized, like old cottages in the country, we often find the first thing that a new owner undertakes is a thorough restoration. And usually this involves a more or less total rebuild of the engine. For it is always assumed that a reconditioned unit must be better than an old one, and certainly no specialist firm out for business is likely to deter you. And regardless of the engine's true condition, it is not unknown for the client to be hood-winked into a total overhaul- crank grind, or re-metalling, re-bore, new pistons and all, on the basis that the job could not be guaranteed without one. Often, the results are disappointing, not to mention the cost. Oil consumption is a common pretext, and perhaps sundry miscellaneous noises in varying degree. But what is generally forgotten is that few vintage engines ran with a Rolls-Royce silence, nor ever approached modern engines as regards oil, most of which seem to use none at all. Indeed, such a goal would then have been considered not only unattainable, but undesirable. By present-day standards all vintage cars drank oil, and when the Rolls-Royce 20hp model came out in 1922, a consumption of 1,000 miles per gallon was considered ‘remarkably low’. And some sleeve-valve Daimlers could only manage 400! The standards of today are mainly due to tighter and more accurate clearances in the moving parts and better piston and ring design, all of which might be applied to rebuilt vintage machinery, but only at a price. For although you are likely to end up with a quiet engine, it will probably be sluggish, run hot at the least provocation and be heavy on petrol, to the extent that the extra cost of fuel easily outweighs the saving on oil. It is like driving with the brakes on, which in effect, is what it is. However, you will be told that - ‘all rebuilds are like this, and things will get much better on running-in, old boy’. But although this for long held true, the story is very different today. Largely due to improved oils, additives and filtration, engines virtually never wear out, and thus it follows that they do not run-in either, for running-in is simply a process of gradual wear. A man well known in the motor trade told me he had recently taken a BMW engine to pieces and the honing marks were still visible in the bores after 100,000 miles! No wonder Peter Lilley's 14/40 MG is nice and quiet;, but still tight after years of extensive motoring, and still is only doing 20 or 21mpg. (In this context, I am told that Castrol sell an old-fashioned ‘straight’ oil; which may be ideal for running-in, but no more details are to hand). Unlike their modern counterparts, vintage engines do not have the power to spare for the inevitable higher friction which results from tighter clearances. The late Freddie Dixon, the ace Riley tuner, said ‘take three thou off everything’ if you want performance and economy. If a Morris engine is free, with the plugs out you should be able to turn it over on the handle with one finger, even when stone cold. Some years ago when I rebuilt my 1929 Cowley UF 5170 (ex-Barraclough), bored out 70 thou to suit Renault pistons, I specified an extra 4 thou clearance in the bores. The engineer was horrified; but the car went splendidly from the start, often does 30mpg at 50 mph, and much to my surprise, uses very little oil. It is however, quite noisy when idling, but you can't have it all ways: The choice is yours!
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