Tuning Data
Fields left blank are ones I am still hunting for correct info. North American cars unless otherwise noted.
| Spitfire | Up to 1977 | Catalytic Converter Specification only |
| Idle Speed | 700-900 r.p.m. | 700-900 r.p.m. |
| Fast Idle Speed (US) | 1700-1900 r.p.m. | 1700-1900 r.p.m. |
| Fast Idle Speed (non-US) | 1100-1300 r.p.m. | – |
| Rocker (valve) Clearance (Cold) | 0.010″ (0.25 mm) | 0.010″ (0.25 mm) |
| Dwell | 1962-74 see Timing data below, 1975-77 fixed | Fixed (Electronic) |
| Carburetter Type | 150 CDSE 1970-? 150 CD4 (? to 1977) | 150 CD4T (1977 on) |
| Needle | A.N. (1147cc w/twin SU) B5AV (US Mk3 & MkIV w/Stromberg) B5CH (1973-74) BIDL (1975-76) | BIDL (1977-78), 45P (1978-79) 45N (1980) 45L (1978-79 California), 45N (1979-80 California) |
| CO Reading at Idle | Min. 1%, Max 3.5% (1970 US spec.) Min. 2.5%, Max 4.5% (pre-1500) 1.5% Nominal, Min. 0.5%, Max 2.5% (US 1500) 3% Nominal, Min. 0.5%, Max 6.5% (non-US) | 3% Nominal, Min. 0.5%, Max 6% (1977) 5% Nominal, Min. 3%, Max 7% (1978-79) |
| Procedure for Setting | Disconnect and plug the air injection system, (downstream of the diverter valve vent pump to atmosphere) and adjust the mixture strength with the external adjuster. To give larger adjustments move the metering needle using a special tool. | |
| Firing Order | 1-3-4-2 (#1 is at front of car)(turning counter clockwise) | 1-3-4-2 |
| Points Gap | 0.015″ Mk1-2 (factory manual says 0.020, but service bulletin revises to .015 in 6/63) 0.015″ Mk3 0.016″ Mk4 0.015″ 1500 | 0.015″ (0.38 mm.) |
| Plug Gap | 0.025″ (0.64 mm.) | 0.025″ (0.64 mm.) |
| Plug Type | Champion N9Y (62-70), UN-12Y (70), N-12Y (71-80) | N-12Y |
| Plug Torque | 25 ft/lbs | |
| GT6 | North America spec GT6 Mk1 | GT6 Mk2 | North America spec GT6+ | Mk 3 |
| Idle Speed | 600-750 r.p.m. | 700-900 r.p.m. | 700-900 r.p.m. | 700-850 r.p.m. |
| Fast Idle Speed | 1700-1900 r.p.m. | 1700-1900 r.p.m. | 1700-1900 r.p.m. | |
| Rocker (valve) Clearance (cold) | 0.010″ (0.254 mm.) | 0.010″ (0.254 mm.) | 0.010″ (0.254 mm.) | 0.010″ (0.254 mm.) |
| Carburetter Type | 150 CD | 150 CDSE (150 CD non-US) | 150 CDSE | 150 CDSE |
| Needle | 6J | 6 AL (6 AC non-US) | B5 AJ | B5BT (B5CF)* |
| CO Reading at Idle | – | Max 2.0% | Max 2.0% | |
| Firing Order | 1-5-3-6-2-4 counter-clockwise (from top of distrib.) | 1-5-3-6-2-4 | 1-5-3-6-2-4 | 1-5-3-6-2-4 |
| Points Gap | 0.015″ (0.38 mm.) | 0.015″ (0.38 mm.) | 0.015″ (0.38 mm.) | 0.015″ (0.38 mm.) |
| Plug Gap | 0.025″ (0.64 mm.) | 0.025″ (0.64 mm.) | 0.025″ (0.64 mm.) | 0.025″ (0.64 mm.) |
| Plug Type | Champion N-9Y | Champion N-9Y AC Delco 42XLS | Champion UN12Y AC Delco 44XLS | Champion N-9Y & N12Y |
| TIMING | static (engine not running) | Strobescopic (at idle with distrib vacuum advance disconnected and plugged) | Stroboscopic (other) | Dwell |
| GT6 | ||||
| GT6 Mk1 | 13° BTDC (100 octane fuel) 7° BTDC (97 octane fuel) | – | – | 40°-42° |
| GT6 Mk2 | 10° BTDC | 4° ATDC | – | 40°-42° |
| GT6 + | 6° BTDC | 4° ATDC | – | ? |
| GT6 Mk3 | 10° BTDC 6° BTDC* (12° BTDC according to 1973 Emissions service bulletin) | 4° ATDC | – | 40°-42° (*38°-40°) |
| Spitfire | ||||
| Spitfire Mk1 | 13° BTDC*** | – | – | 36° |
| Spitfire Mk2 | 13° BTDC*** Haynes says 17° | – | – | 36° |
| Spitfire Mk3 | 6° BTDC | 6° ATDC | – | 40°-42° |
| Spitfire Mk3 w/emissions | 6° BTDC | 2° ATDC (800-850 rpm) | – | ? |
| Spitfire Mk4 (non-US) | 6° BTDC (up to FM25000) 8° BTDC (after FM25000) | ? | – | ? |
| Spitfire Mk4 | 6° BTDC | 2° ATDC (800-850 rpm) | – | ? |
| Spitfire 1500 (non-US) | 10° BTDC | 10° BTDC (650-850 rpm) | – | 46°-56° |
| Spitfire 1500 up to 1976 | 10° BTDC** | 2° ATDC | 14° (plus or minus 2°) BTDC at 1100 rpm | 38 to 40 deg. fixed for electronic ignition |
| Spitfire 1500 1977-79 | 10° BTDC** | 10° BTDC | 14° (plus or minus 2°) BTDC at 1100 rpm | fixed |
| California Spitfire 1500 up to 1976 | 2° ATDC** | 2° ATDC | – | fixed |
| California Spitfire 1500 1977-79 | 10° BTDC** | 2° ATDC | – | fixed |
* after KC or KF 10000
** Electronic Ignition. A few manuals I found recommend against using static timing on cars with electronic ignition.
BTDC= Before Top Dead Center
ATDC= After Top Dead Center
***The recommended timing for a Mk1 or Mk2 Spit. Adjust as follows:
1. Rotate the Vernier adjuster knob counterclockwise until it won’t turn anymore.
2. Position the crankshaft so that the front cylinder is at TDC and ready to fire. (The pointer on the timing chain cover will be lined up with the timing mark on the pulley)
3. Rotate the distributor body clockwise until the points just begin to open (make sure the rotor is pointing to the #1 piston) A test lamp is helpful for this operation.
4. Tighten the distributor clamp to lock the distributor in place.
5. Rotate the vernier adjuster knob until you achieve 13 degrees of advance (each click of the adjustment knob is equal to 1 degree of advance)
This timing chart is under construction as I have found MANY inconsistancies between sources.
Please email me any revisions, corrections, additions.