Mr. Javelin would indeed care to respond thus:
The 803 is a much maligned and reviled engine. The performance figures are nothing special and the preceding sidevalve engine was stronger - but we must remember that this was 1952 and the change from S.V. to O.H.V. would have been remarkable in such a cheap car.
The top speed is academic. Realistic maximum cruising speed on an 803 fitted with original spec. transmission is 45 MPH. Some have indicated 70 MPH on the speedo but that is pushing to the absolute limit - as my own observations have proved.
The bottom end is very weak, the big-ends being made from white metal and the oil pump and lubrication system not exactly the best in automotive history.
Fuel consumption is poor for the size of the engine and power output. (Or it may just be that my carb has had it).
However, one must remember that these engines are plodders, made before the motorway age and will happily run all day at speeds of 40 MPH. How often does a Minor have the opportunity to exceed this speed for Heaven's sake?
Having just rebuilt my own 803 on 88,000 miles and not needing a rebore, I will be running this engine extensively to see just how long they do last.
Summing up, then, the 803 WILL do its job perfectly well - it just takes slightly longer and does it in a more noisier fashion.
P.S. I will be updating my '803 rebuild progress' thread with the results from the oil restrictor made by Rolf Corbat and supplied by Declan Burns.