RUMBLINGS By BOANERGE,S.”
ALTHOUGH to the ordinary citizen there may be seasons of the year when certain overhauls should be undertaken on a motor car, to the man who is really trying to get the best out of his model there is no close season. If the motor is getting tired it must be dealt with at once if not sooner. The fact that some people prefer to do it sooner may explain why the results are not always very clever, as you can’t mend something which is already O.K.—However, what is of more immediate concern is the fact that motors do get tired for a variety of reasons apart from such simple routine matters as carbon deposit, etc.
One of the commonest causes of that mysterious falling off of revs is worn valve seatings, and this is specially common in sports car engines for two good reasons. One is that no keen owner will continue to run an engine in which the compression is not absolutely up to scratch, and as a result the valves are frequently being reground ; and another is that with modern camshafts and the consequently strong valve springs they require, give the valve seatings a most uncomfortable time, and result in a sort of masked valve, without a camshaft to match it. The falling off in power due to the restricted valve opening is far greater than people realise, especially as it happens so gradually that it is often far gone before being really noticed. I was forcibly reminded of this during a recent visit to Baritnar’s works, where Mr. Brett showed me a formidable array of cylinder blocks and heads from all types of engines, which had come in to be rejuvenated in this particular department. These included a fair number on which repairs had already been attempted by the use of “false ” seats, and although various methods of fixing these have been tried by many firms, they are not satisfactory, and I ‘gaw several cases where the seats had come loose or shifted and so completely upset everything. Some
others had caused the head to crack in the vicinity owing to insufficient metal being left round the seat.
The method used by Barimars for repairing worn seats is to build up, by welding to the original shape, and then machining the seat again. In all the examples I saw of this method, the job was absolutely indistinguishable from new, and certainly seems the obvious method of doing it—that is providing that there is sufficient welding experience behind the firm doing it. The job certainly requires great skill and it would be a very foolish course to try and save money by letting anyone who had not the great experience of a firm like Barimars behind them to attempt such a job.
Another advantage of this method is that the building up is done with a harder grade of iron than can be used for manufacturing cylinders and heads, and therefore the rebuilt seatings should have a longer life than the originals. I would willingly have spent a whole day in looking round at the various welding processes going on, such as building up cams and other worn parts, and of course, repairing crank-cases.
Lack of space forbids further description of these, but the question of valve seatings is of such importance that I cannot refrain from drawing attention to it.
Shelsley Again. The attraction of Shelsley was again proved on Saturday, 13th of last month, when no one seemed to think that it was far to go from London, judging by the host of spectators which hailed from the south. At the last minute I found myself landed temporarily without a motorcar to get there, so something had to be done quickly. I mean, one couldn’t not go to Shelsley (why can’t you learn to speak English ?En. Well you know what I mean— Bon.) Anyway the solution of the trouble was found to be a phone call to Aldington of Frazer-Nash’s, and could he lend me a motor car ? He
was very sorry, but the ..,only spare vehicle was a works hack which he explained (a) had not been down for 16,000 miles, (b) had some totally unsuitable carburettors and simply would not go at all, and I must not imagine for a moment that a FrazerNash was really as bad as that, etc., however, if I had nothing else, I was welcome to take it,—and who could say fairer than that ? Well, after about 500 miles in that car I can only say, that if that is Aldington’s idea of a tired motor, some other sports car makers had better pull their socks up and start tuning.
I started late, as usual, and arrived in time — most unusual — and in spite of perfectly beastly weather the whole time, put up a higher average than I have ever done over this particular route. Actually Aldington was right, the car was slower than is the habit of this breed, but knowing something of its recent past, the wonder is that it had survived at all.
The only other vehicle which showed that the performance was at all under par, was another FrazerNash which just, and only just, managed to leave us behind. What a joy to have a car that will hold its tune to that extent after thousands of miles of blinding, and still reel off 300 miles as an incident in the day’s work, without the least sign of protest.
The way it sits the road and corners is a positive joy, and I couldn’t help being amused at Aldington’s prayers not to say anything about its performance, as it wouldn’t be fair ! However, MOTOR SPORT is due for a road test of one of the latest Frazer-Nash’s, as soon as one can be withheld from a customer long enough to be used as a demonstrator. At present he is finding that all his motors are sold before they are built, a very happy state of affairs for him, but rather disappointing for those who haven’t vet had a Frazer Nash and want to hear all about it. But, when the new works are in full swing we may be more fortunate.