1971 Lotus Elan Sprint restoration
1971 Lotus Elan restoration thread
Read the full write-up at 1971 Lotus Elan restoration thread ↗
1971 Lotus Elan Sprint: body, chassis and engine refresh after decades of ownership
The owner, who has had this 1971 Lotus Elan Sprint since the mid-1980s and already fitted a galvanised Lotus chassis around 1990, is now refreshing the bodywork and mechanicals after the car suffered damp damage while stored outside. The thread follows the body going off for paint stripping and glassfibre repair, the chassis being cleaned and powder coated, and the engine, gearbox, propshaft and diff being sent out for assessment and a power-focused rebuild.
Specs
As stated in the original write-up.
- Engine
- Lotus twin-cam with Sprint big-valve head, L14 camshafts, standard rating 126bhp, rebuild targeting around 140bhp
- Carburettors
- Twin 40DCOE Weber carburettors
- Gearbox
- 4-speed manual
- Final drive
- 3.77:1 ratio (standard Sprint); a 4.125 diff was tried for a time and later reverted
- Chassis
- Lotus galvanised chassis, fitted around 1990 during an earlier rebuild, later powder coated for cosmetic refresh
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.
Engine 3
- Lotus twin-cam engine with Sprint big-valve cylinder head
Original Sprint-spec engine sent for a performance rebuild aiming for around 140bhp from the standard 126bhp
In the shops
Heater Water Valve - Lotus Europa S2/Twin Cam/Elan 2+2 ↗
Sports & Classics· $39.95 USD
Lotus Europa Twin Cam Interior Kit ↗Sports & Classics· $1,895.95 USDLotus Europa Twin Cam Interior Kit ↗Sports & Classics· $1,295.95 USD - L14 camshafts
Existing cams retained and currently fitted, noted as a good road cam ahead of rebuild work
- JS Motorsport engine, gearbox, propshaft and diff rebuild service
Took in the engine, gearbox, propshaft and differential to assess wear and carry out the engine rebuild
In the shops
Gearbox Rebuild Kit ↗James Paddock Ltd· £149.95 GBP
Gearbox Rebuild Kit (4-Speed) ↗
Gearbox Rebuild Kit - Manual Mk3 ↗
Fuel & Ignition 1
- Twin 40DCOE Weber carburettors
Pair of Weber DCOE carburettors fitted to the engine, one choke per cylinder
In the shops
Weber 40DCOE Carburettor ↗
Kelvedon Lotus (Kelsport)· £525.00 GBP
Weber 40DCOE Carburettor Rebuild Kit ↗Lotus Marques· $38.85 each
Weber 40DCOE Carburettors (Sprint Spec, Pair) ↗Kelvedon Lotus (Kelsport)· £915.00 GBP
Gearbox & Drivetrain 2
- 4.125 final drive differential
Fitted for a period to sharpen acceleration before being swapped back to the standard-type 3.77 diff
In the shops
Final Drive Pinion 17 Tooth 3.76 Pre A+ ↗
Mini Sport· £25.58 GBP
Standard Full Helical Final Drive Pinion ↗Mini Sport· £97.19 GBP
Final Drive Kit - LSD Semi Helical 3.93:1 ↗Mini Sport· £241.79 GBP - 3.77 final drive differential
Reinstated as the car's running final drive ratio after the 4.125 diff was removed
In the shopsFinal Drive Pinion 17 Tooth 3.76 Pre A+ ↗Mini Sport· £25.58 GBPStandard Full Helical Final Drive Pinion ↗Mini Sport· £97.19 GBPFinal Drive Kit - LSD Semi Helical 3.93:1 ↗Mini Sport· £241.79 GBP
Other 1
- Lotus galvanised chassis
Fitted to replace the original chassis during an earlier rebuild around 1990; later stripped, pressure washed and powder coated
Photos
16 pictures collected from the write-up, in the order they were posted, shown from 1971 Lotus Elan restoration thread. A picture opens larger here, with the way through to the page it is on.
NTG999 · 2020-12-04T20:10:40+0000 3this post at 1971 Lotus Elan restoration thread ↗
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How it was done
Starting condition
The owner has had the Elan Sprint since the mid-1980s and had already replaced the chassis with a galvanised Lotus item around 1990. More recently the car was left under a cover outside while another car used the garage, and it suffered damp damage, prompting a full bodywork and mechanical refresh.
Body repairs
The body, weighing roughly 100kg, was lifted off the chassis by hand and sent away for paint stripping, crack repair and re-fibreglassing. Once paint was stripped, only minor evidence of old accident damage at the front was found, which was due to be corrected.
Chassis
The galvanised chassis was stripped and pressure washed. Although still structurally sound, it was sent for powder coating purely to freshen its appearance rather than for added protection, since the car is kept in a heated garage.
Engine and drivetrain
The engine, gearbox, propshaft and differential were removed and handed to JS Motorsport. The gearbox had worn synchros and the propshaft needed balance checking. An inspection of the engine found most wearing parts worn out, and a rebuild proposal was drawn up aiming to lift output from the standard 126bhp to about 140bhp using the existing L14 cams with head work.
Progress so far
By the end of the thread the powder-coated chassis had been returned and could be built up as a rolling unit, though the carburettors needed removing again to refit the body. The engine rebuild and final reassembly were still ongoing.
A summary in our own words. The full account, with all its detail, is in the original write-up: read it at 1971 Lotus Elan restoration thread ↗
Worth knowing
- Leaving the car under an outdoor cover while the garage held another car let damp in and caused costly damage
- Powder coating a galvanised chassis is worthwhile mainly for appearance rather than protection if the car is garaged