Tuning Data

Fields left blank are ones I am still hunting for correct info. North American cars unless otherwise noted.

SpitfireUp to 1977Catalytic Converter Specification only
Idle Speed700-900 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)
Dwell1962-74 see Timing data below, 1975-77 fixedFixed (Electronic)
Carburetter Type150 CDSE 1970-?
150 CD4 (? to 1977)
150 CD4T (1977 on)
NeedleA.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 IdleMin. 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 SettingDisconnect 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 Order1-3-4-2 (#1 is at front of car)(turning counter clockwise)1-3-4-2
Points Gap0.015″ 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 Gap0.025″ (0.64 mm.)0.025″ (0.64 mm.)
Plug TypeChampion N9Y (62-70), UN-12Y (70), N-12Y (71-80)N-12Y
Plug Torque25 ft/lbs
GT6North America spec GT6 Mk1GT6 Mk2North America spec GT6+Mk 3
Idle Speed600-750 r.p.m.700-900 r.p.m.700-900 r.p.m.700-850 r.p.m.
Fast Idle Speed1700-1900 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 Type150 CD150 CDSE (150 CD non-US)150 CDSE150 CDSE
Needle6J6 AL (6 AC non-US)B5 AJB5BT (B5CF)*
CO Reading at IdleMax 2.0%Max 2.0%
Firing Order1-5-3-6-2-4 counter-clockwise (from top of distrib.)1-5-3-6-2-41-5-3-6-2-41-5-3-6-2-4
Points Gap0.015″ (0.38 mm.)0.015″ (0.38 mm.)0.015″ (0.38 mm.)0.015″ (0.38 mm.)
Plug Gap0.025″ (0.64 mm.)0.025″ (0.64 mm.)0.025″ (0.64 mm.)0.025″ (0.64 mm.)
Plug TypeChampion N-9YChampion N-9Y
AC Delco 42XLS
Champion UN12Y
AC Delco 44XLS
Champion N-9Y & N12Y
TIMINGstatic (engine not running)Strobescopic (at idle with distrib vacuum advance disconnected and plugged)Stroboscopic (other)Dwell
GT6 Mk113° BTDC (100 octane fuel)
7° BTDC (97 octane fuel)
GT6 Mk210° BTDC4° ATDC40°-42°
GT6 +6° BTDC4° ATDC?
GT6 Mk310° BTDC
6° BTDC*
(12° BTDC according to 1973 Emissions service bulletin)
4° ATDC40°-42° (*38°-40°)
Spitfire Mk113° BTDC***36°
Spitfire Mk213° BTDC***
Haynes says 17°
Spitfire Mk36° BTDC6° ATDC40°-42°
Spitfire Mk3 w/emissions6° BTDC2° ATDC (800-850 rpm)?
Spitfire Mk4 (non-US)6° BTDC (up to FM25000)
8° BTDC (after FM25000)
Spitfire Mk46° BTDC2° ATDC (800-850 rpm)?
Spitfire 1500 (non-US)10° BTDC10° BTDC (650-850 rpm)46°-56°
Spitfire 1500 up to 197610° BTDC**2° ATDC14° (plus or minus 2°) BTDC at 1100 rpm38 to 40 deg.
fixed for electronic ignition
Spitfire 1500 1977-7910° BTDC**10° BTDC14° (plus or minus 2°) BTDC at 1100 rpmfixed
California Spitfire 1500 up to 19762° ATDC**2° ATDCfixed
California Spitfire 1500 1977-7910° BTDC**2° ATDCfixed

* 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.