Ultimate P4 Q car


Guild member Ian Portsmore owns this spectacular Rover 110, CAS, which he has modified very tastefully as you will read below. In the metal it is easy to look at CAS and think that it is a standard car. However, on looking closer and under the bonnet it is a very different story of outstanding engineering craftsmanship. Ian has delighted many folk at Guild events and in 2019 when CAS appeared on the Guild's stand at the NEC Classic Car Show where those trying to look at the car were sometimes 4 deep!

In addition to CAS, Ian owns two other P4s, a 1963 95 which had been off the road 25 years, and a recently acquired restoration project 1962 110 which has been off the road for 10 years. WIthout doubt Ian will be applying his magic to these P4s. Ian also contributes to the Guild's magazine, Overdrive, with recent articles about engine oils and coolants, where his engineering knowledge is shared with our members. Back to CAS now in Ian's own words.......

This 1962 110 was bought as a ‘rescue job’ for £550 from eBay ten years ago in a fairly sorry state. This burgundy P4 was languishing in a shed on a farm in Shropshire needing a fair bit of work, the car had at some point in the past been prepared for banger racing, and then saved and loosely put back together, a terminally ill rover 90 engine and 95 non o/d box were sat in place which whilst they ran (just) and moved under their own power, they were beyond economical repair. In reality the car itself was beyond economical repair also but the project was taken on anyway. Much work / welding / fettling was carried out to make the car solid and safe once again over a period of several months, which left the question of drivetrain replacement.

I had owned two V8 conversions previously and was interested in making this one a V8 conversion also. Whilst the P4 may appear to be an ‘oddball’ car to be fitting a large V8 to, the design in reality lends itself far better than most to the conversion. The enormous separate chassis and the same brakes that also stop a not far short of 4000lb mk3 3 Litre coupe from over 100mph make for an excellent base. Initially a rebuilt Chevrolet Corvette V8 engine with 6 speed manual gearbox was fitted. This engine was not a difficult conversion as the physical size was not much greater than a rover V8, with forward swept tubular exhaust manifolds there was sufficient clearance to retain the original steering box and the sump hump cleared the central steering bar.

At this stage of development of the vehicle a heavy duty front anti roll bar was in place, a 3.54 P5b diff utilised, the dampers refilled with heavier oil and 7/8” P5b rear wheel cylinders employed. Coupled with vehicle weight reduction of around 400lb pulling up sharply from over 100mph at a drag strip was accomplished with ease. The car was fun to drive and with a high efficiency high compression engine and a 0.5 ratio sixth gear it would return 32mpg on a regular basis, whilst being quicker up the standing quarter mile than a Ferrari Testarossa.

After a few years the Small block GM engine was replaced with a period 1960’s design 385 series Ford ‘Lima’ engine rebuilt to my own spec, fitment of which needed several engineering solutions to be attended to as the physical external dimensions of the engine block were considerably larger than the previous GM unit. The bulkhead within the confines of the vertical reinforcement ribs was moved rearwards by 3” to make room, the steering box was replaced in favour of a modern Ford rack and pinion unit. The exhaust manifolds were hand produced full length tubular items crafted at the expert hands of Tony Laws Exhausts in Leeds. These tubular manifolds feed into a twin 3” system with two large stainless silencers to keep noise to a minimum, mostly for the neighbours benefit.

The leaf springs were no longer able to cope with the increased torque so the decision was made to fabricate and install a rose jointed 5 link axle location with coil springs replacing the leaves. The diff was sent away to XS 4x4 diff specialists where a KAM Diffentials 2.83 to 1 ring and pinion were fitted, with a Quaife Automatic Torque Biasing differential unit in the centre (like a limited slip diff but better).

All round QA1 re-valveable racing shocks from Summit Racing in Ohio are now fitted with 900lb front springs and 275lb rears. The 900lb springs whilst sounding harsh only give a 325lb wheel rate due to the wheel rate being bottom arm distance ratio squared x actual spring rate, with the P4 bottom arm ratio being around 0.6 at the centre of the spring. Front brakes have been replaced with billet aluminium 4-pot callipers from Fosseway Performance (originally intended as an E-Type brake upgrade) giving the car the ability to pull up sharply from over 130mph. Needless to say there are a whole raft of other additions, improvements and upgrades to make the car drive as well as it does, too many to list here.

Two pairs of original steel rims were sent off to Alonze fabrications in Scarborough who are a wheel banding specialist, and came back 20mm wider on the outside, 30mm on the inside, which still fit within the confines of the original rear arches. One pair now wear a pair of rear drag slicks and the other pair with 225/80 r15 rear tyres for the road. Whilst the gearbox is now a 3 speed auto with no overdrive the car still achieves 20mpg on the road thanks to 13:1 static compression, tall axle gears and tyres, and a killer multi spark per firing stroke ignition system. The car has been built to be a road car rather than a race car and as such the engine is in a relatively mild state of tune and is very driveable regardless of journey type or distance. This 110 is currently doing the quarter mile in 10.5 seconds crossing the finish line at 133mph, which is quicker than a 2006 Bugatti Veyron. In English 0 to 60mph is in three seconds, and 0 to 100mph is in six.

The ethos with this 110 during the last 10 years has been to have a P4 with a period V8 conversion with the necessary updates and upgrades but still appear original, including retaining the standard ride height, and has won several ‘Spirit of the Show’ type trophies in recent years.

Ian Portsmore
Rover P4 Drivers' Guild Member
January 2021


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