Classic Car Mart Spring 2016 61
How it works: Volvo OHV engine
Four versions of the B18 were produced from
A to D, the letters denoting camshaft grinds. The
A variant was reserved for the basic 121 model,
with a single carburettor (initially Zenith, later
Stromberg), low compression pistons and a mild
cam. The B18B was introduced in the now sought-
after 123GT model in August 1966. Offering the
highest power output (115 bhp) and specifi cation,
these were the range-topping Amazons, featuring a
three-spoke steering wheel, auxiliary driving lights
and Recaro-designed reclining bucket seats.
Discounting the B18C that was primarily used
in military applications, the B18D powered the
122S, a mid-level specifi cation with twin SU HS6
carburettors and 90bhp against the 121’s 75.
Power outputs rose slightly for the B18A,
B and D engines until 1967 – at that point the
new B20 unit intended for the new 140-series
became ready. The B20 was created by boring
out a B18 from 84mm to 88.9mm, and was
fi tted to all Amazons after 1968. The engine
features split bore centres, meaning a greater
spacing between the centre cylinders than the
outer pairs.
Again, the B20 was available in several
different versions. The 8.7:1 compression,
single-carb B20A was good for 82bhp and the
B20B was a twin-carb version running 9.5:1
compression and 118 bhp.
Bosch D-Jetronic was used for the injected
B20E producing 135 bhp from 10.5:1
compression and the emissions-friendly B20F
with 8.7:1 compression and good for 118 bhp.
The 1.6-litre B16 version of the engine was debuted towards the end of PV544 production and would be carried over into the Amazon range.
The Amazon used the 1778cc B18 version of the B-Series engine, a four-cylinder overhead valve unit that had earlier been adapated for marine and agricultural applications.