How-To & Repairs
Task-focused, plain-English guides written for AC Aceca owners. Every guide is original; precise torque and clearance figures defer to the workshop manual; safety-critical or specialist work should always be entrusted to a specialist.
- CoolingDIY2 to 3 hours plus draining time
Flush and refill the cooling system
A biennial cooling-system flush is the single most valuable maintenance job on an Aceca. It removes scale and old inhibitor that quietly line the radiator core and cylinder-head passages, letting the system shed heat properly and preserving the radiator.
Open the guide - FuelDIY / Specialist1 to 2 hours with the engine warm
Balance and mixture-set triple carburettors
The three carburettors on any Aceca must draw equal airflow at idle before mixture can be sensibly set. This is done with a balance meter, each carburettor's throttle stop adjusted independently, then mixture walked in per carburettor until idle is smooth.
Open the guide - IgnitionDIY1 hour
Set points, dwell and ignition timing
Setting points gap, dwell and ignition timing on the Lucas distributor is straightforward when done in the right order. Static-time to get the engine running cleanly, then strobe-time warm with a timing light for the definitive setting. All figures come from the workshop manual for the specific engine.
Open the guide - BodyDIY / SpecialistHalf a day plus paint drying
Arrest early aluminium-body corrosion
Blistering or white powder on an Aceca panel is usually galvanic corrosion where the aluminium skin meets the steel body frame; separately, the ash timber in the frame can rot where damp is trapped. Both are arrestable if caught early and ruinous if ignored. This guide covers cosmetic touch-in only, structural frame repair is a coachbuilder's job.
Open the guide - BrakesDIY1 hour with two people
Change brake fluid and bleed the system
Brake fluid absorbs water from the atmosphere and should be renewed every two years or so. Old fluid drops the boiling point of the system, causing a spongy pedal or fade under repeated braking. The job is straightforward with two people and takes an hour.
Open the guide - ElectricalDIY / Specialist2 to 3 hours
Diagnose the Lucas dynamo and control box charging system
The Aceca charges through a Lucas dynamo and a separate control box, not an alternator. Most charging complaints are a slipping belt, poor earths, a dirty or mis-set control box, or worn dynamo brushes, rarely the dynamo failing outright. Confirm the car's earth polarity before connecting anything, as reversed polarity destroys components.
Open the guide - TransmissionDIY / Specialist1 to 3 hours to diagnose
Maintain the gearbox, clutch and overdrive
The Aceca has a four-speed manual gearbox, a Moss box on AC-engined cars, Bristol's own on the Aceca-Bristol, an AC alloy-cased box on the 2.6, often with a Laycock de Normanville overdrive on the upper gears. Most 'gearbox' faults are really clutch, linkage or overdrive-electrics problems, so diagnose before dismantling.
Open the guide - EngineDIY1 hour to investigate
Read and protect the engine's oil pressure
Oil pressure is the clearest indicator of health on the Aceca's six-cylinder engines. Learn your engine's normal hot and cold readings from the manual, watch for a low hot-idle figure, and act on any downward trend early, most bottom-end damage follows months of quietly falling pressure that was there to be seen.
Open the guide - EngineDIY / Specialist2 to 3 hours, unhurried
Check and set the valve clearances (Bristol engine)
The Bristol six sets its valve clearances through an unusual cross-pushrod head: one camshaft in the block works the inlet valves directly and the exhaust valves through transverse pushrods that cross the top of the head. There is more linkage to understand and to wear than on a normal engine, so work methodically to the manual's figures, and if in any doubt, use a Bristol specialist.
Open the guide - CoolingDIY / SpecialistAn afternoon, worked through methodically
Diagnose an overheating Aceca
An Aceca that runs hot almost always has a findable cause: a furred or blocked radiator core, a weak water pump, a stuck thermostat, retarded ignition or a weak mixture, a slipping fan belt, or simply air in the system after coolant work. Work through them in order, cheapest and most likely first, before assuming the worst.
Open the guide
Electrical articles
- Electrical
The Lucas Control Box: Voltage Regulation on the AC Aceca
What the control box does, how to spot when it's misbehaving, and how to cure the commonest fault: overcharging.
Read the article - Electrical
Calibrating the Lucas Voltage Regulator on the AC Aceca
The open-circuit method, temperature-corrected voltage figures and the cut-out setting for the RB106.
Read the article - Electrical
Fitting a Solid-State Regulator Inside the Lucas Control Box
Choosing the right positive-earth unit for your dynamo, the wiring, and what to expect on the first run.
Read the article - Electrical
The Wiring Loom: Makers, the Lucas Colour Code and Earthing
Replacement looms are made to order by engine type. The Lucas colour code, where the factory wiring diagrams live, and why a wooden framed car needs so many earths.
Read the article - Electrical
Positive Earth: What It Means for Your Aceca, and Why It Matters
Why British cars were positive earth, how to tell whether yours still is, and what it means for the battery, coil, dynamo, charging and modern accessories.
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Horn and Indicator Wiring: the Stator Tube and Its Lucas Switch
How the horn and indicator wiring routes through the steering column, the safe way to thread it, and why you must never prise the old switch apart at its base tags.
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Ownership articles
- Ownership
Before a Long Run, and After: An Aceca Checklist
Fluids, tyres, brakes and charging before a long drive, the Bristol and triple-Solex quirks to watch, spares to carry, and the return check.
Read the article - Ownership
Driving an AC Aceca Through the Winter
The honest case for and against: salt and washing, galvanic corrosion, underbody protection types, and when to leave it in the garage.
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Chassis articles
Transmission articles
- Transmission
The AC-Engined Car's Gearbox: the Moss Box and the 2-Litre
What the early Ace and Aceca share with the AC 2-litre saloon, and the hydraulic clutch adaptation a 2-litre box needs.
Read the article - Transmission
The Clutch and Its Hydraulics: Borg & Beck, Two Master Cylinders
Every Aceca has a hydraulic Borg & Beck clutch, but the master cylinder differs by engine. The bracket fault worth ruling out first, and the Bristol freewheel.
Read the article - Transmission
Gearbox & Freewheel: Moss, Bristol and the Freewheel First Gear
Which gearbox your car has, the Bristol box's freewheel first gear, the overdrive option and how to look after them.
Read the article - Transmission
Driving a Gearbox with No Synchromesh on First Gear
What synchromesh does, why early boxes lacked it on first, and how to select first cleanly, from rest or on the move, by double-declutching.
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Steering articles
Brakes articles
- Brakes
AC Aceca Front Disc Brakes: Calipers, Discs and What Fits
Girling part numbers, the caliper shared with the TR4 and Greyhound, the AC-specific disc, and the unsettled question of what has to be machined to make them fit.
Read the article - Brakes
Brake Fluid: Types, Checking, Choosing and Changing
Glycol DOT 4 or silicone DOT 5, how to tell which your car runs, what to check before a drive, and when to renew it.
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Brakes: Girling Drums, Al-Fin and the Move to Discs
The 11-inch Al-Fin drums, the front discs from 1957 to 58, and keeping either set-up safe.
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Bodywork articles
- Bodywork
Body & Ash Frame: Aluminium, Ash and Where It Rots
Hand-formed aluminium over a steel-tube and ash frame, the fibreglass bulkheads and early hatchback, and the two ways the body decays.
Read the article - Bodywork
Doors That Won't Shut Tight: Why, and the Fix
Why an Aceca's heavy ash-framed coachbuilt doors stop shutting tight, and how the right adjustment usually cures it.
Read the article - Bodywork
How to Prop the Bonnet Open
The forward-hinged alloy bonnet needs the correct prop, in the right hole, at the right angle. A 2-minute safety check before working on the engine.
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Fuel articles
- Fuel
AC Aceca Fuel System: Tank, Pump and Delivery
The tank, pump, lines and filter that feed the carburettors, the common faults, vapour lock, and what modern ethanol petrol means for the system.
Read the article - Fuel
Fuel Pump Location and Over-Fuelling (AC Engine)
Why the pump belongs low and near the tank, and why flooding is usually float height, needle valves or pressure instead.
Read the article - Fuel
Setting Solex Float Levels on the Bristol Engine
The two proven methods specialists use, fuel level and needle valve, plus the float faults to check when the level won't come right.
Read the article - Fuel
Starting in Extreme Heat: Hot Fuel and the Aceca
Vapour lock, percolation and the heat-soak window, why a hot Aceca won't restart, the roadside cure and the lasting fixes.
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Bristol engine articles
- Bristol engine
Removing the Bristol Camshaft: With the Engine In, or Out?
One owner's account of the job: the distributor drive gear clip that forces the oil pan off, the timing cover and damper carrier, and the correction he made to his own conclusion.
Read the article - Bristol engine
Fitting the Oil Temperature Gauge: the Vokes "Dog's Bone"
Where the sensor goes on a Bristol engine, the sump fallback after a spin-on conversion, and testing the Smith's capillary gauge.
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Storage articles
- Storage
Storing an AC Aceca Over Winter
Damp, fuel and the ash frame, laying the car up properly, and waking it again in spring.
Read the article - Storage
Storage, Humidity and Dehumidifiers
Three materials, three decay paths, one cause: what humidity to hold, desiccant against compressor, floors, pouches and batteries.
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