A Letter from one Enthusiast to Another about Working on an Anzani-Engined Frazer-Nash

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36

(The following is a letter which Mr. J. G. Hay wrote recently in reply to a fellow enthusiast who had acquired an old s.v. Anzani-engined Fraser-Nash and raised some servicing queries. Because it touches in so refreshing a manner on a number of points which trouble those strange to these cars, and contains so many invaluable wrinkles gleaned by Hay while working on his own car, we are reproducing it verbatim. — Ed.)

Chains. — Adjustment is largely a compromise between individual chain adjustment by adding or subtracting links or cranked links. (Get some of these cranked links if you can, they’re very useful, and James Grose, in Ruston Road, I think has some — 3/4 by 9/16 in. is the size.)

The thing to aim for is to get the axle and counter-shaft exactly parallel — most easily done with a pair of ordinary inside-callipers between the two adjacent parts of the radius arm over the thread.

Best adjustment is to leave about 3/4 in. up-and-down slack on one side of the chain, at several different positions of the rear axle — i.e., jack up and turn the shaft right round to check for tight spots due to bent axle or countershaft, or distorted sprockets.

Line up the sprockets to one another very carefully with a straight edge, letting the counter-shaft sprockets go back against their thrust faces, away from the driving dog. This is important. If you have an axle sprocket that tends to “float” axially on the axle, the usual method is to put a sleeve of sheet metal round the axle between the loose sprocket and its neighbour, or against the bearing end, and fixing this with hose-clips.

Make sure that the adjustment nuts on the radius arms are locked up tight; there is a danger that the radial action may take place there instead of at the proper place, with disastrous results to the adjusting threads and so on.

Brakes. — So far as I know the brake layout you describe was perfectly standard. One can modify by taking the single lever off the near-side end of the foot-brake cross-shaft and putting it on the off-side hand-brake cross-shaft and making or acquiring a double lever for the near-side foot-brake. It’s hardly worth doing, as the standard system is remarkably efficient. What is worth doing is to discard the front cables and fit solid rods. I used 3/8-in, rod and screwed the rear ends 3/8-in. B.S.F. to fit the wing nuts on the cable end adjusters and bent the front ends, hot, to go through the lever ends on the front axle shafts and drilled and split-pinned in position. The difference in braking-power is considerable.

Dynamo drive. — Your engine may have been blown at some time, but I think the reason for the alteration is probably due to trouble in the original drive, a bronze to steel skew gear, or to a defective dynamo and no correct replacement available. I had to modify mine last year using a 12-h.p. Austin dynamo and cradle on the lower side of the crossmember just in front of the bevel-box, driven through an Austin Seven flat fan belt to an Austin speedometer pulley on the dynamo. This is a bit slow but keeps the battery up perfectly satisfactorily, charging at about 7-8 amps. at normal engine speeds.

This drive was the standard one with the G.N., as far as I remember, except that a split pulley on the shaft and a Whittle belt were used. (The belt used to break at high speeds and administer very considerable chastisement to the driver through a plywood board and a very Spartan cushion.)

Bevel-box. — Definitely not grease; treat it as an ordinary rear axle — after all, it’s just the same, except that there is no differential. If you have the countershaft out, make certain that the sliding dogs have a slight clearance between the top of the key and the base of the keyway, and that the keys fit snugly in the shaft and are perfectly flat and square. Otherwise they lift or rock slightly and tend to jam. Also, it’s worth checking the fit of the sprocket bearings on the counter-shaft, since a wobbly sprocket will either throw its chain or wear its own teeth sideways against the inside of the links. It need not be a perfect fit, but any considerable slop should be rectified by re-bushing.

Clutch. — This should be assembled on the bench. Make sure that the fingers are lined up straight on their pivots and that the four fulcrum posts are secure in the back-plate. Put the fingers in place and screw up the nuts on the four pull-rods nearest the rim of the front plate until they are solid against the rear face of the front plate. This is important. Slide the sleeve, thrust-races and spring along the shaft until the thrust-collar just presses on the fingers. Now, unless you are extraordinarily fortunate, the fiddling begins. Being a hand-made job in the first place and after twenty years of re-adjustment by loving hands, it is most unlikely that all four fingers are alike, so they will not meet the thrust-collar evenly. So you start changing them round, marking or otherwise identifying them first so that you don’t end up on the same holes as you started. If that doesn’t work, thin washers under the shoulders of the pull-rods will work the oracle. You say you have a new clutch, so perhaps you will not have all this to do, but if it is a relined job you certainly will, and it’s a lot easier to do it on the bench than standing on your head inside the car.

If it is a reline job, with the standard 1/4-in. thick Ferodo segments, the job should be fairly straightforward. If thinner Ferodo has been used, however, the angle of the fingers or levers may be wrong and the pull-rods will have to be shortened by machining back the 5/16-in. diameter, any subsequent re-lining of the clutch being covered by the addition of washers.

The tensioning of the spring is best done in position, by trial and error, i.e., by removing all tendency to slip and driving the clamp another quarter or half inch up to allow for wear. This is the only adjustment necessary, assuming the assembly is correct. New fibre blocks on the withdrawal fork are advisable, and the firm have a supply.

The foot-brake cross-shaft is dropped to remove or refit the clutch assembly; this is easier than taking out the clutch cross-shaft. Plenty of grease on the withdrawal races and centre-bearing, and on the ball-thrust pin inside the flexible coupling at the rear end of the shaft, and the job is done. Do not let any oil or grease get on the shaft near the spring clamp, which should be tight.

Engine mounting. — The steering-box mounting is standard and has no snags, except that any slack in the off side engine-bearer bolt (1/2-in. B.S.F.) allows the engine to move against steering reaction. Cure is to ream out and fit a larger bolt, 11/16 or 5/8-in. The first notice one usually gets of this trouble is when the engine speeds up or slows down during turning operations, due to the engine moving in relation to the accelerator pedal.

Tappet clearances and timing chains. — I forget the correct figure, but I set mine to 0.006-in. inlet-0.008-in. exhaust hot, and the engine seems to like it. With the sudden-death cam profile of these engines, the valve-gear is always noisy anyway, so a thousandth or two over the original setting is of little moment. How are your timing chains?

They are a rather weak point in these engines and are non-adjustable. Best way of investigating is to take hold of the magneto coupling and try to turn it, first one way and then the other. The first bit of slack is the mag.-chain, but go on trying, and you will be able to turn the cam-shaft slightly against the resistance of the valve-springs. If these chains, of the inverted tooth variety, are allowed to run too sloppy, the sprocket teeth get chipped and worn and the chains are liable to jump. I speak with some authority on this point, having waited since before Christmas for new chains, and got them from Frazer-Nash last week. They had to get them specially made, but got a dozen of each so there are some left.

Ignition timing. — Your cylinder head will allow of a lot of advance, even on “Pool” petrol. I should set it to kick back on the handle when the magneto is in the half retard position, experimenting from there on actual performance, generally running as far advanced as she will go without pinking.

Carburation. — The large Solex was standard. My present one had a horrible little 3-jet Zenith on it when I got it eighteen months ago, which I immediately threw away in favour of an enormous S.U., a brand of which I am very fond. Unfortunately, the piston is rather too heavy for a 1 1/2-litre engine to lift, so I am looking for an aluminium one to replace the present bronze unit. But consumption is around 40 m.p.g. and performance was good enough for 24.4 seconds and 2nd (Vintage) place to Denyer at Elstree last year, so I’m not really complaining.

General. — My top-gear sprocket on the axle went west last summer, and the best Nashes could do was a 24-tooth replacement, so my ratio is down from 3.98 to 1 to a more modest 4.2 or so. I altered third at the same time for sprint work and hill-climbs, as I find that 3,000 r.p.m. is about the efficient peak of these engines, and I don’t like winding them up too far in second. So I’m now running 11.5 to 1, 8 to 1, 5.7 to 1, and 4.2 top, with a maximum of about 75 m.p.h., or perhaps a little better, and an all-day cruising speed of 60-65 at around 38-40 m.p.g. This is really slightly on the weak side and though the valves don’t mind, the rather poorly constructed outside manifold is slowly disintegrating. By the way, a B.T.H. magneto is rather tall with an outside manifold; if you can construct some sort of an aluminium shield over it, it may save trouble. (I dismantled a Lucas mag. seven times in one day to remove shellac from the armature tunnel, at the Vintage meeting at Bisley last summer.) I subsequently fitted a B.T.H. magneto, with a piece of heavy sheet aluminium held by the strap nut about 3/4 in. clear of the magneto and bent up in front so as to catch an air stream over the timing case. No further trouble.

Chassis. — Nothing particular apart from the brake-rod modification; steering about 1/8-in. toe-in; gear-oil in the steering box, not grease. If the rear brake-drums rub on the back-plates due to axial displacement of the shaft bearings, it is safer to pack the brake drums out slightly with 5/16-in, washers on the studs, rather than try to move the axle in the housings. Shock absorbers are important if you want to motor quickly. I ran mine at Prescott last August with the rear shock-absorbers non-operative and couldn’t hold the car at all through the bends. Gear-shift linkage adjustment is important, so ensure that the dogs engage fully before the arm in the cross-shaft touches the gate, and if you have no rocking-plate on top of the bevel box to prevent double engagement, it’s worth while making one. I think they were standard on all 1926 models, as well as later. Incidentally, have you 6-volt or 12-volt electrics? My last one, definitely 1926, was 6-volt, and my present one, believed 1927, but quite possibly older, is 12-volt.

My present ‘Nash is registered as 1939, having apparently been rebuilt and re-declared then, and its early history is unknown. Chassis and engine numbers are 4640 and H.E.4893. How do these compare with yours? There is a hole in my scuttle bulkhead, on the near side, which might have housed a tank; the body has been pushed in at the back to clear the filler spout of a 12-gallon tank hung between and below the chassis extensions carrying the spare wheel and rear shock absorbers. Unfortunately, some so-called enthusiast fitted cycle-type front mudguards, which rattle, jam up with mud, and generally spoil the appearance of the car. I envy your bronze-plated cylinder head; I approached the firm who used to do it the other day, but there’s no hope of it at present.

Joins G. Hay.

[Frazer Nash owners may be interested to know that an article on the development and tuning of these cars, from the Anzani-engined cars, through the Meadows-engined jobs to the six-cylinder Blackburn-engined cars appeared in Motor Sport for March, 1936. A few topics of this issue are still available, price 2s. 2d. post free. — Ed.]