MCRobbie's Jaguar 420G Restoration
Jaguar 420G Restoration Project (blog)
Read the full write-up at Jaguar 420G Restoration Project (blog) ↗
Photo: Jaguar 420G Restoration Project (blog)Reviving a dormant Jaguar 420G after decades off the road
MCRobbie's blog follows the recommissioning of a Jaguar 420G that had sat unused for over 20 years, with help from his Dad and a friend Phil. The posts cover fixing fuel delivery and cooling problems, brake faults and electrical gremlins, culminating in the car passing its first MOT in 23 years and being driven on the road again.
Specs
As stated in the original write-up.
- Engine
- 4.2 litre straight six (original Jaguar 420G engine)
- Fuel system
- Triple SU-type carburettors
Parts used
Parts named as used in the original write-up, grouped the way the Parts page groups them. Where one of the shops we index lists the same thing for this car, it is shown underneath with a link to the shop.
Fuel & Ignition 1
- Fuel pump
Swapped out when the original stopped running; later replacement sprang a leak causing a fire
Cooling 1
- Replacement thermostat
Fitted after the original top hose was found blocked with solidified antifreeze
Brakes 1
- Brake fluid reservoir floats
New floats fitted after originals disintegrated, resolving brake warning light
In the shops
Square Brake Fluid Reservoir ↗
Moss Motors – Triumph TR6/TR250· $22.99 USD
Brake Fluid Reservoir Cap and Float ↗
bpnorthwest.com· $72.84 USD
Jaguar Brake Fluid Reservoir With Switch ↗
Sports & Classics· $79.95 USD
Interior 1
- Wiper arm rubbers
New rubbers fitted to wiper arms to properly clear the windscreen
In the shops
Wiper Arm ↗Moss Motors – Triumph TR6/TR250· $42.50 USD
Wiper Arm, Right Hand ↗Moss Motors – Triumph TR6/TR250· $32.25 USD
Wiper Arms, Blades & Motors ↗Moss Motors – Triumph TR6/TR250· $0.00 USD
Electrical 1
- Distributor cap, rotor arm, points and condenser
Replaced as part of getting the engine to start
In the shops
Distributor Cap, Screw In ↗Moss Motors – Triumph TR6/TR250· $14.42 USD
Points & Condenser Set, Aftermarket ↗Moss Motors – Triumph TR6/TR250· $0.00 USD
Condenser for Twin Points Distributor ↗James Paddock Ltd· £6.25 GBP
Tools & Workshop 1
- Welder
Used by the owner to repair two corroded jacking points on the driver's side
Photos
14 pictures collected from the write-up, in the order they were posted, shown from Jaguar 420G Restoration Project (blog). A picture opens larger here, with the way through to the page it is on.
How it was done
Starting condition
The car had been off the road for 21-23 years, stored in a garage. It had stale fuel in both tanks, a leaking header tank with multiple holes, rotted brake fluid reservoir floats, notchy steering, corroded jacking points and tired paint, though the underside was reported surprisingly solid.
Getting it running
The team replaced the distributor cap, rotor arm, points and condenser, fixed a wiring error, cleaned stale fuel from the tanks, stripped and cleaned the carburettors, and got the engine running smoothly. The header tank was patched and the carbs balanced and timed by Phil.
Brakes and cooling
The brake fluid reservoir floats had disintegrated; both reservoirs were flushed and new floats fitted, resolving a dashboard warning light. The cooling system was flushed clear of solidified antifreeze blockage and a new thermostat fitted; minor leaks were sealed by tightening jubilee clips.
Electrical and small repairs
Wiper arms were fitted with new rubbers, wing repeater contacts were cleaned to restore function, the electric aerial was freed up, and two corroded jacking points were welded and repaired. Lights, horn, indicators and washers were all checked working.
MOT and first drives
The car passed its first MOT in 23 years with no advisories. It was then driven on short and longer trips, revealing a heavy brake pedal, rough steering and a boot that popped open, plus a developing grinding noise from rear brake pads after years of inactivity.
Ongoing fuel troubles
A later fuel pump fault caused a fire when it sprung a leak and shorted against the body. A blocked fuel pickup was traced to a dirty tank and a sticking carburettor bowl valve, which once cleaned allowed the fuel system to pressurise properly and the engine to run well again.
A summary in our own words. The full account, with all its detail, is in the original write-up: read it at Jaguar 420G Restoration Project (blog) ↗
Worth knowing
- Wire the distributor points correctly to avoid shorting the ignition system
- Stale fuel and dirty tanks can block pickups and need thorough cleaning before trusting the fuel system
- A leaking fuel pump can be a serious fire risk if it shorts against the car body