Reece Fish Carburettor conversion
Another magazine articles on sportier Viva HA’s, this time featuring the Reece Fish Carburettor.
The light, lively little Vauxhall Viva, with its free-revving 1,057 c.c. over-square power pack and fully-flowed “balanced” head almost in Stage 1 tune, is a sitter for the “improvers”. So much so that Bob Henderson of M.P.G. & H. Ltd. (Soho Mills, Hackbridge, Surrey) is developing a Formula III racing engine from it.
Meantime, as a start for its roadgoing conversions, the firm has produced a simple carburetter swop for the Viva which turns the small family car into a quick-off-the-mark vehicle that can show a clean pair of heels to most. The improvements are not all to acceleration. Nearly 10 m.p.h. is added to the top end. All this is achieved with little sacrifice of original economy. A road average of 50 m.p.h. under give-and-take conditions gave 32 m.p.g.
The conversion is simple and can be carried out by the average handyman in an hour or less. In place of the Solex carburetter, a Fish unit (fully described in our June 1963 issue) is bolted on to an adaptor on the manifold, the original accelerator linkage being retained. This carburetter, with no other modifications, steps up the original back wheel b.h.p. of 33 to 39-plus b.h.p.
In performance the biggest improvement comes in above 50 mph. Up to 50 m.p.h. from a standstill the Fish Viva shows a 1.7 second gain over the standard model; is six seconds faster to 60 m.p.h.; and 14 seconds to 70 m.p.h. These are impressive figures. Above 75 m.p.h. (5,000 r.p.m.) the rate of acceleration tails off, and about a further three-quarters of a mile is needed to reach its 84-85 m.p.h. maximum. However, on a slight downhill gradient it reached 90 m.p.h. at 6,000 revs without undue fuss.
At 75 m.p.h. it cruised quietly and comfortably, with still nearly 10 m.p.h. in hand for overtaking.
The excellent Viva gearbox, with its well- chosen ratios and short precise travel, contributes a great deal to the enjoyment of the car. First gear gives 23 m.p.h., second 45 m.p.h., and third 73 m.p.h.; but it was found in our acceleration testing that it was best to change up at 6,000 r.p.m., giving 42 m.p.h. in second and 68 m.p.h. in third.
Unfortunately the original rear suspension does not cope with fast roadwork as easily as the engine and gearbox. The back end is twitchy and can readily be made to hang out, particularly on wet roads, although it is not difficult to correct. If the car were to be used for quick cross-country journeys it would pay to stiffen up the rear shock absorbers and suspension generally. If acceleration is all that is needed the suspension is adequate as it stands.
During hard acceleration, non-enthusiast passengers found the carburetter roar unpleasant. But this dies out as cruising speed is reached. Air cleaner/silencers are available as an extra for this conversion and cost from £2 2s. 6d. to £6 10s. according to type. Because the vertical intake manifold leaves little room under the bonnet the cleaner is bolted to a bracket on the nearside wheel arch and is connected to the carburetter intake by flexible trunking.
More noticeable when the engine was hot was the flat spot when the accelerator was depressed, through a too-rich acceleration shot being pumped down the vertical inlet manifold. In later conversions this has been overcome by a modified separator between the float and inner chambers of the carburetter which has a “bleed” to reduce the pressure in front of the fuel pick-up arm and, therefore, the amount of petrol forced into the carburetter intake.
Although the engine started first time even when the car was left out in freezing weather great care had to be taken only to depress the accelerator a quarter of an inch before using the starter motor. The carburetter has, of course, no choke. Weakening the initial shot; will have the effect of making starling a less delicate operation. The Fish is susceptible to heavy-footedness. On this, as on all Fish-carburetted engines, the accelerator can be backed off much further than normal when cruising speed has been reached.
Cost of the Fish carburetter conversion for the Viva is £27 10s., or £30 fitted. Alternatively a new Viva with a Fish installed is list price for the car plus £30.
Next stage in the M.P.G. & H. conversion is a “detuned” camshaft to reduce interference from the centre siamesed exhaust port and increase top-end performance. The exchange cost of this will be £12.
To sum up, the Fish Viva is a roomy and flexible family car with a performance that raises eyebrows.