The Twin Cam MGB, using presumably a marriage of 1,798 block and twin
cam heads, is of course feasible, but it is unlikely that any
manufacturer would invest the time and money involved in producing
heads. The MGA Twin Cam is as rare as hen's teeth - they only built a
little over 2,000 of them - and so the market for unique parts is very
small. If you have unlimited funds, then fine - I am sure someone will
fulfill the fantasy. In fact, if you have UNLIMITED funds - well hey
buddy.......
As an aside, did you know that the MGA Twin Cam was almost called the
MGB? John Thornley referred to it as such in internal MG/BMC memoranda
in the mid-fifties. At that stage, the `MGC' was envisaged by Syd Enever
as a big coupe tourer with the BMC `C' series six, and the `MGD' was a
small Midget replacement. The original MGC idea expired, but was revived
as an off-shoot of the MGB in 1961/2, becoming the ADO52 MGC of 1967/9,
whilst the MGD idea died in favour of the Austin-Healey Sprite, which
spawned the Midget Mk. I.
In the planning of the MGB that we know and love, Abingdon originally
envisaged two versions, one with the 1,622 c.c. standard ohv engine and
a `super' version with the twin-cam. In the end, the twin-cam was too
much of a liability, and so right after Sebring 1960 the plug was
pulled. So there is some potential justification for a `what if?' car.
There have in fact been some twin-cam MGB's built in the UK, but these
do not use the `B' series block. First, a bit of background: as you may
know, the MGB was originally to have received the `O' series engine,
which shared many basic internal dimensions with the `B' series
(designed to use much of the same production machinery). Launch should
have been in 1981/2, with fuel injection for US versions and either
twin-SUs or turbocharged induction for other markets. Of course the `O'
series MGB never happened (the engine was also intended for a facelifted
TR7) but the engine was used by BL in other cars not sold in the
'States. The Rover SD1 2000 used a twin carb in-line rear 2.0 litre `O'
series, whilst the MG Maestro and MG Montego used the 2.0 litre in
transverse front wheel drive guise, with turbo-charging optional. I
drove an early MG Montego Turbo and it was an ANIMAL.
The `O' series evolved, and in 1985 spawned a twin cam version known as
the `M16'. This engine, with a block adaptable to the MGB and TR7/Rover
SD1 5-speed transmission, came with fuel injection as standard. This
engine subsequently appeared in a few MGB's, particularly once the
Heritage bodyshells came along. Time waits for no man, and so the M16
engine itself was eventually consigned to history. In 1992, the `T'
series came along - and is still in production today for the Rover 420
and 820. This is a very nice engine, far removed from its distant `B'
series cousin but the link is nevertheless there. It will die within a
couple of years, to be replaced by Rover's own 2.0 litre KV6 and a joint
BMW/Rover engine to be built at an all-new factory in the British
Midlands.
I am not sure but I suspect that someone in the UK has at the very least
thought about putting a `T' series in an MGB. Both the M16 and T series
were also available in turbo versions, offering up to 220 bhp. Of
course, both the M16 and T series are rarer than the fillings in hen's
teeth in the USA....
At the end of this lengthy discourse, I think the answer is (what was
the question?) - either to use normal tuning (heads, carbs etc.) of the
normal B series (with an enlarged capacity if possible) if legislation
permits or throw away the 'B' series and slot in a Buick/Rover V8. Those
will be far more effective ways to blow Miatas into the weeds.
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