Volvo 121 ‘Amazon’
Has Jon finally found the cause of the Volvo’s woes?
1966 VOLVO 121
The internet loves to give advice but isn’t always right. Numerous people have tried to diagnose my Amazon’s recurring habit of cutting out after driving at dual carriageway speeds and I’d taken a fair bit of flak from the community for swapping the standard Zenith 36VN carburettor for a Scandcar – a Spanishmade Weber 34 ICT. Truth is, the Zenith was worn out, its re-build kit hopeless and the twin SU alternative, spoken of in hushed tones, would have necessitated fitment of a different inlet manifold, choke linkage, throttle linkage and downpipes.
New Zeniths run to a hefty tab, too – and I was so sick of the Amazon’s antics and having to heel-and-toe at every junction to keep it running that the Weber seemed the most costeffective way of taking the carburettor out of the equation.
Installed, it made very little difference; the fuel pressure was where it should be and the fuel pump was functioning, but the problem persisted. I roped in ex-rallyist and knowledgeable old car fettler, Pete Murray. With his help, we chased out the possibility of air leaks and focused instead on timing and ignition settings.
A custom-made adaptor, 3D-printed by a friend, sealed up the mouth of the carburettor against the tin air cleaner; thinking that the carb mixture might be getting too warm (the Amazon’s head is pre-crossflow) we lifted the Weber out of the way using a phenolic spacer from a VW specialist.
The car definitely picked up better on my now infamous test loop on the picturesque country lanes around Conwy, but still cut out at junctions following a drive along the A55. Having checked the timing, Pete recommended setting the dwell angle according to the factory repair manual; having bought a multi-meter capable of measuring it, driveability improved once again, but I still had to resort to fancy footwork to avoid causing jams at traffic lights.
Pete cleaned the plugs and tweaked the Weber to no avail. The car happily pootled around the castle walls and could have run up to the national speed limit with no issue – unless you had to pull off the A55.
We may have bodged the broken sunroof closed and freed off the heater levers that had seized during lockdown and tier measures, but the elephant in the room was still choking the 121 whenever I came to a halt.
As daylight began to fade, I checked the third-time-replaced ignition-coil and found that it was hotter than the interior of a tandoori oven vomiting up a solar flare. Could we have finally found the root cause of
the problem?