I modified my Dad's brand new HB Viva SL90

by Alan Warwick

Well, it must have been August 1966 travelling back overnight from North Wales that we spotted a pretty dark blue saloon on trade plates coming down the A41 - probably from Vauxhall's Ellesmere Port factory. It didn't have any badges except for a "V" in the centre of its front grille and, as an apprentice at Vauxhall dealer Capital Motors in Hornsey, I knew a new shape Viva was to replace the HA in the latter part of 1966 - so I assumed correctly this was it! 

Standard - as delivered

When I arrived back at my Tottenham home I enthused about its attractive shape and encouraged my Dad Fred to order one as our family car to replace the Hillman Husky currently serving us OK. 

As the new "E" suffix registration plate was to be issued from the 1st of January 1967 we waited until then for delivery of our Glacier white Vauxhall Viva SL90 with the higher performance engine, black upholstery and DISC brakes. It was delivered with the then new-fangled Dunlop Radial tyres - SP41s I think and 41/2 J wheels.

I was working on the shop floor so was allowed to fit all the extras in my lunch hours; Motorola 5 push button radio, wing mirrors with base-plates, fog and spot lamps etc and an alarm. The alarm was not a success as it went off on windy nights or if someone jogged the car but the immobiliser switch hidden under the dash gave us a sense of security. ​

I had passed my test in the Husky but my Mum Winifred, sister Ann, girlfriend Sue (later my wife of over 50 years) and my sister's boyfriend Geoff ( later etc, etc ) all had driving lessons in the Viva which consumed clutches at around 25,000 mile intervals. Fortunately I could fit a new clutch in our garage at home in an evening so this was a minor problem, Dad's kindly wallet providing me with a trolley jack and axle stands for the purpose. These were also useful when i carried out jobs for friends and family in evenings and weekends. 

Most of the mechanics (the term we used in the '60s, I HATE the word "fitter" - which implies someone who just "fits" parts rather than being competent to diagnose as well. I refer to myself as a "Motor Engineer" which seems good to me. Rant over!) at Capital Motors modified or "tuned" their cars and my Dad trusted me when I suggested modifications at around 30,000 miles.

This was the mileage that a de-coke (de-carbonising the cylinder head) was often carried out, so I proposed this as well as fitting a downdraft Weber 28/36 DCD carburettor to replace the "stroppy" ( as we referred to it ) Stromberg. At the time we had difficulty in getting a good slow-running tickover with the Stromberg on most "90" engines and the superior quality of a Weber was a desirable alternative, giving more performance when required.

Brabham Viva

I removed the cylinder head in our home garage and took it to work, taking the valves out in my lunch hour and getting the local engineering company Johnson Roberts to machine 60 thou (60 thousandths of an inch) off the mating face of the 'head.

​This was to increase the compression ratio, releasing superior performance from the red 1159cc engine. 60 thou was recommended by the others in the 'shop but the '90 cylinder head was already a higher compression than standard and this was too much - BEWARE other tuners!! More of that later.

I cleaned up the valves, re-ground them into the freshly-machined head and fitted Terrys stronger valve springs, went home, re-fitted the cylinder head (new gasket with Wellseal sealant as Vauxhall instructions) and added the Weber carburettor on its Blydenstein inlet manifold. Bill Blydenstein was a former racing driver of Borgward Isabella cars who moved on to supplying tuning parts for '60s Vauxhalls and Gerry Marshall was one of the most noteworthy drivers of Blydenstein Vivas. There was a lot of "fettling" of the linkage required to get full throttle on both carb butterflies which included a piece of one eighth welding rod with a sliding nipple.
​
Weber 28/36 DCD carburettors operate the first "choke" or butterfly up to 5/8th throttle and give excellent economy driven this way but, when you floor the right-hand pedal both "chokes" come into play as well as the accelerator pump jet which gives enhanced performance. 

This was the Brabham Viva setup I was used to in the Capital Motors workshop

Twin-Choke Weber carburettor

In addition to the cylinder head and carburettor work I had managed to persuade Dad that his Viva "needed" the benefit of the Brabham Lukey exhaust system as we were used to fitting on the current Brabham Vivas. He was very trusting with his wallet. 

A Mobelec electronic ignition system was also fitted, replacing the contact breaker points and condenser (capacitor) which was designed to keep the sparks consistent rather than deteriorating as the points gap altered with wear. I didn't bother Dad with the technicalities - he was more inclined to his touring bike Campagnolo gears…...

Back to the 60 thou off the head, after I'd finished the work I found severe "pinking" unless 5 star petrol was used but as this was readily available at the time it caused no real problem. BEWARE others with "90" engines, i think this may apply to all Viva HC engines, too. 

Not long after the SL90 was back in use by several family members, I fitted Spax adjustable shock absorbers (dampers) which stopped "bounce" and made it more stable in corners. Really a front anti-roll bar would have helped as well.

Several cosmetic improvements were carried out including getting the original Vauxhall steering wheel and gear knob stitched with leather as one of my friend's family ran the Formula Steering Wheel company. I also fitted a flush spotlight on the rear panel (opposite the fuel filler) as a reverse light as we had a long unlit drive to reverse up to our garage. And it looked cool! 

Our SL90 in the garage where I modified it

Not ours, but a 21st century photo of a very similar car

The modified Viva around 1971 in Cuddington, Bucks

The best things about these modifications is that the Viva ticked over smoothly, was much nicer to drive, had improved fuel consumption and my parents thought it an improvement with no side-effects. Even the three-silencer Brabham Lukey exhaust didn't make extra noise to cause complaints from "the oldies"! I don't think they ever "discovered" the performance given when opening the throttle over 5/8ths. 

The car gave reliable service until around 70,000 miles in 1972 when it was sold to my sister and her husband to make way for Dad and Mum's new Vauxhall Viva HC model X14 automatic, but that's another story…….