Volvo 3 Litre Technical Issues
Stephen Fairhurst describes a suspension adjustment and how he has fitted triple
carburettors to his Volvo 3 Litre
A pdf version of this article can be downloaded here...
Volvo 3 Litre
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I bought my Marcos Volvo 3L in 1999 as a good running car and have been impressed
with its design and quality for a low production GT, much better than the Trident
I had before this. |
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I had to fit new front uprights and steering column. Although this removed the free
play, a vibration resulted caused by seizing dampers (old 1970's SPAX). Before fitting
new dampers I tried a Triumph TR saloon column rubber donut. This makes motorway
cruising more refined without affecting steering feel too much. This might sound
strange for a Marcos, but in Kent using motorways is almost unavoidable. The donut
can be fitted to the rack end of the column using two splined adaptors as there
is only a small angle. |
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Previously, I have run a Triumph GT6 MK II on a daily basis. Despite using the same
front suspension, the Marcos feels quite different and better balanced. I had fitted
twin 1¾" SU carburettors to my GT6 using Triumphtune adaptors (in place of 1½" Strombergs)
which gave about 20% more power. |
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The Volvo engine is also a straight six but has a different port layout which makes
a two carb manifold difficult without unequal port lengths. I looked in Vizard's
book on the 'A' series engine and decided that in effect three 'A' series manifolds
with three 1¾" SUs would be better. The standard manifold has twin 175 Strombergs.
Due to the limited underbonnet space, short dashpot HS6 SUs from a Triumph Dolomite
Sprint were used. These were obtained from a specialist for £25 each. Parts for
the HS6 are easy to obtain. Ram pipes and filter socks are available from Demon
Tweeks. Some carbs have Waxstat jets which lean the mixture when hot. This can be
deactivated by uncrimping the base and removing the pin, then fitting a washer or plate to reset the jet height. |
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The new manifold was made in Kent but took nearly a year as it was fitted in between
race car jobs, but it was cheap. I left a spare head and manifold along with some
sketches. It incorporates inlets and exhausts on a common flange plate. I asked
for a balance pipe between the inlets and they welded on a spare Volvo crankcase
breather pipe connector (with restriction). |
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The throttle linkage was made using spare SU linkage parts and some steel tube/rod
from B&Q. The SU clamps fit 8mm OD rod/tube. Luckily my Dad has a welder and
he welded the brackets to the manifold. |
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Using three carbs on a straight six means that the gaps between induction strokes
are not equal for
each carb. Finding a rolling road specialist to set up the carbs
is not easy. Any recommendations would be appreciated. |
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Stephen Fairhurst |