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MORGAN PLUS 8 BUYER’S GUIDE

MORGAN PLUS 8 BUYER’S GUIDE

Posted by Matt Bell on 4th December 2019

The Morgan Plus 8 offers brilliant performance in an elegant shell. Here’s what you need to know before going out and buying one.

A Morgan Plus 8 is about as British as roast beef on a Sunday. Not many cars come as British as the Morgan, and for that reason, its customer base has meant that the company has existed for over a century when others have fallen. Still to this day Morgan is producing cars; a testament to British engineering and our love for sports cars.

The story of the Morgan Plus 8 arrival is an odd one. It was well known that during the ’60s, a four-cylinder sports car was no longer big enough to keep up with customer demand. Triumph’s answer to this problem was to produce a six-cylinder TR5, but the problem for Morgan was that the straight-six was simply too long to fit in the 4/4 body. Lotus’s twin-cam was considered but regarded as too fragile, and Ford’s V6 was too tall and too heavy.

Left in a bit of a predicament, it was Rover that came to the rescue but in an odd scenario. Peter Wilkes, director of Rover, visited Morgan in an attempt to acquire Peter Morgan’s business. Although Morgan politely declined the offer, the two reached an agreement for supply of the recently developed Rover V8 engine. The lightweight design was still in the process of being adapted from the Buick/Oldsmobile unit used in Buick cars from 1960 to 1963.

Production of the Plus 8 began in 1968 and ran for 36 years until 2004. In this period, 6000 examples were built and many are still available to this day. Over its lifespan, however, its body and technical specification changed significantly with the last of the breed coming with a fuel-injected engine and five-speed transmission. Here’s what you need to know before buying one.
Morgan Plus 8

Body

The Plus 8 body came in one style, a two-seat open tourer, although one hardtop coupe was produced on chassis number R7317. The coupe proved too complicated and not economically viable to build, leaving Morgan to stick to its winning formula of open top driving.

The 8 came with a much squatter presence than its predecessors. In the early cars, the overall width was 4ft 9in, with a track of 4ft 1in. This spread wider in years to come when in August of 1973, the track was measured at 4ft 3in at the front and 4ft 4in at the rear, with the total width equalling 4ft 11 in. This then changed in 1977 when the wings were replaced with steel instead of aluminium, width stretching to 5ft 2in, with a 4ft 5in track at the front and 4ft 6in in the rear. A final increase in width appeared in 1981 when it became 5ft 3in, this being done to accommodate new alloy wheels.

Until 1986, the steel chassis had little protection from the weather, so if you’re looking to buy one now and the chassis has not been replaced then it is bound to be rusty. Of particular interest is rust in the side members, around the hole which supports the engine mounting brackets and at the junctions where the crossmembers meet the main Z-section side members. The simplest way to check for rust is to tap along the chassis with a screwdriver. A different tone, or a dull note, will indicate rust. Do not patch weld this, it is far better to replace the whole chassis member, which can be ordered from the factory.

Morgan Plus 8

A good option here is to have the chassis shot-blasted and coated. It has also been noted that drilling a few holes into each of the crossmembers and filling with Waxoyl can further prevent rust.

The condition of the ash body frame all depends on how the car has been stored and whether the car it’s been subjected to extreme damp for a period of time. If not dried off properly, for example, an 8 can rust within 10 years. Luckily, rot is easy to spot where you can see the wood: place your fingernail onto the wood and if you can press it then it’s more than likely rotting, alternatively, if an end looks a bit knobbly, this will also indicate rotting.

Within the door frames, if the door appears difficult to shut, this can also indicate problems and similarly if the hinge pillar tries to twist or move with the door it could be down to rot. If there is any rot here, or anywhere for that matter, the whole section must be replaced to eliminate the rot. The sections are inexpensive, but as the body needs to be removed, the labour can be costly.

Morgan Plus 8

Engine

As mentioned previously, the Morgan made use of the then-new Rover V8 engine. The Plus 8 initially ran the engine in exactly the same state of tune as the Rover P6 3500, with a 3528cc capacity, although some V5s will say 3532cc as this was written in error.

Getting the engine into the Morgan was a tight squeeze and required a few modifications, some unconventional. For starters, the airbox was ‘carefully’ modified by placing a plank of wood on it and hitting it with a hammer to create a gap for the bonnet hinge to sit in.

Rover claimed 151bhp and 210lb.ft of torque offered at 2750rpm. However, with five-star fuel being phased out, in 1973 power output was reduced to 143bhp and 202lb ft of torque due to the compression ratio change from 10.5:1 to 9.35:1.

In 1976, the engine was replaced with the one used in the SD1, meaning power was upped to 155bhp. This was upgraded in 1983 to a fuel-injected engine also used in the SD1 Vitesse. The capacity remained the same but featured re-profiled inlet ports for improved flow and a higher compression ratio of 9.75:1, offering 190bhp and 220lb.ft of torque.

Morgan Plus 8

From June 1990, the engine used switched to a 3946cc Range Rover unit producing the same power outputs as previous. The very latest Plus 8s used a 4.8-litre BMW V8 producing a mammoth 367bhp and 370lb.ft of torque.

As Morgan has used a multitude of engines through all of its models, available parts are determined by what other models they appeared in. Unfortunately for the Plus 8, the only other car that shared the Rover 3500S engine was the P6, meaning some parts are impossible to get hold of: for example, the cast exhaust manifold. As a result, buyers of the 4/4 rather than the 8 are in a better position in terms of restoration. On the flip side, however, the Rover engine is regarded as extremely strong, with 100,000 miles not being too much of an issue should it have been looked after well.

The main issue to note is in the retention of the cylinder heads. While the early Rover V8 engines had 18 retaining bolts for each head, the later SD1 engines had an outer row of four bolts missing, and this creates potential uneven stress. This could result in unburnt petrol and exhaust fumes to contaminate the engine oil, resulting in bore wear and cam/crank bearing failures. This issue wasn’t resolved until 1994 with Morgan’s use of the Land Rover engine when the heads were bolted to the block by 10 evenly distributed bolts.

Morgan Plus 8

Transmission

In the original Plus 8, the Rover V8 was too torquey for the Rover manual gearboxes, so a Borg Warner automatic transmission was put in place. Thankfully in 1971, Rover introduced an all-synchromesh four-speed manual box for the 3500S saloon. As a result, Morgan customers were offered the same new gearbox in 1972. Chassis number R7475 was the first to receive the manual gearbox, but the last car to receive the automatic gearbox was chassis R7494, due to typical teething problems.

The new gearbox was based on the design of the Rover 2000 unit, but with stiffer casing, an integral oil pump driven through the back of the layshaft, taper-roller layshaft bearings and shot-peened gear teeth.

The four-speed manual gearbox was replaced with a similar unit but with five-speeds. This was produced by the newly merged BL/Rover group.

In terms of owning one now, parts for the original Moss automatic gearbox and four-speed Rover unit are unfortunately not easily come by. Later, when the SD1 engine was used, this came with its own five-speed gearbox and parts are more readily available in comparison, but are no longer produced so you will have to source from aftermarket companies, or from donor cars. You should note that from 1985 when the fuel-injected SD1 Vitesse engine was used, the internals between that and the previously used SD1 engine are not interchangeable, which causes yet further problems.

That being said, it has been noted that most of the gearboxes used by Morgan are strong and reliable, and should the transmission oil have been changed regularly you shouldn’t have many issues on that front. Morgan recommended using automatic transmissions oil in all boxes, even in the manual variants.

You shouldn’t have many problems with later SD1 gearboxes with many owners reporting that tuned 8s running close to 300bhp and featuring regularly on track have held up remarkably well with the correct maintenance. Officially they were rated at 245lb.ft but this figure is mostly always conservative.

Morgan Plus 8

Suspension and steering

As any Morgan enthusiast will tell you, the Plus 8 makes use of Morgan’s famous sliding pillar suspension system. Essentially this was carried over from the 4/4, with the same Armstrong telescopic front and lever arm rear shock absorbers being used, but the top springs were different as they were one coil shorter at the front.

Again, as is the theme with Morgans, a good car is a car that has been well maintained. Although that sounds obvious, many of the problems that arise are simply because maintenance was not kept up and the suspension system is the same. Without being too technical, an oil button was provided on the top of the transmission tunnel which allowed a trickle of oil to dribble down the suspension kingpins. By now, if not changed, that oil will have been contaminated and the phosphor-bronze bushes used will have been affected by this.

You should expect the bushes to wear, at best, every 15,000-25,000 miles, due to the friction of moving up and down. When assessing a car to buy, you should check for breakage of the cross-tube lugs at the bottom of the suspension pillar mounts.

The suspension system is very firm which has meant that some people have converted to telescopic rear dampers. This does improve the car but it isn’t original, so depending on what you’re after, this may or may not affect your decision.

All 8s have an extruded mesh AC Delco type collapsible steering column, which was placed through a crowded engine bay. As the car, and more importantly, the wheels, became wider, the car’s steering became heavier and heavier. It wasn’t until 1986 that that a rack and pinion system became standard. Although you can get an earlier car with the same system as from 1984 it was an option costing £1100.

The cam and peg systems originally used will have now worn. Luckily for 8 owners, the Burman system used is much the same as the Gemmer box, made in France. As a result, they are interchangeable. Also, an option for early 8 owners is to switch entirely to the newer rack and pinion system. Although removing some of the original characteristics, you’ll end up with a better all-round car.

No matter which steering rack is used, the track rod ends will wear and rust if not greased properly; signs of worn track rod ends, or one that is drying up, is that the steering becomes much heavier than usual, something to look out for on test drives.

Morgan Plus 8

Values

As you’d expect, Morgan Plus 8 values are particularly strong. Even by today’s standards, the Morgan can provide tantalising performance with a unique Britishness that is so desirable. As a result, we found few below the £20,000 mark with the very cleanest examples, mostly of late ’80s-’90s builds costing close to £80,000. Some have been used in historic racing and it’s best to ask whether cars have been used on track days as even track-prepared cars can fetch close to £50,000.