MGB 18V Engine Tuning Data (ECE 15 European Spec) - Timing, Plugs, SU HIF4
MGB Engine Tuning Data for 18V engines to European ECE 15 emission spec: compression 9.0:1, idle 750 rpm, fast idle 1,100-1,200 rpm, 15 BTDC strobe timing, Lucas 25D4 distributor, exhaust 3-4.5% CO.
This document is page 72 of an MGB workshop manual (marked "Engine Tuning Data 6, MGB. Issue 2. 83910") presenting complete engine tuning data for 18V engines built to European emission control requirements (ECE 15). It lists engine specifications: 18V type, 109.8 cu. in. (1798 c.c.) displacement, 1-3-4-2 firing order, 9.0:1 compression ratio, 170–190 lbf./sq. in. cranking pressure, .015 in. cold valve rocker clearance, 750 r.p.m. idle, 1,100–1,200 r.p.m. fast idle, and ignition timing (15° B.T.D.C. stroboscopic at 1,000 r.p.m.; 5° B.T.D.C. static). Distributor data covers the Lucas 25D4 (serial 41032): contact breaker gap, spring tension, anti-clockwise rotation, 60°±3° dwell, a five-point centrifugal advance curve (0–3° at 600 r.p.m. up to 17–21° at 2,200 r.p.m.), and vacuum advance figures (starts 3 in. Hg, finishes 8 in. Hg, total 14°±2°). It also specifies the Lucas HA12 ignition coil (3.1–3.5 ohms primary), Champion N9Y spark plugs gapped .024–.026 in., S.U. HIF4 carburetters (specification AUD 434, .090 in. jet, AAU needle, red piston spring), and an exhaust emission target of 3 to 4.5% CO at idle. Useful for tuning and setting up a European-spec MGB 1798 c.c. engine.
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Frequently asked questions
- What is the ignition timing for the MGB 18V engine to European ECE 15 spec?
- Stroboscopic timing is 15° B.T.D.C. at 1,000 r.p.m.; static timing is 5° B.T.D.C. The timing marks are a pointer on the timing case and a notch on the crankshaft pulley.
- What spark plugs and gap does the MGB 18V European-spec engine use?
- Champion N9Y plugs, gapped .024 to .026 in. (.625 to .66 mm.).
- What distributor is fitted and what is the dwell angle?
- A Lucas 25D4 distributor, serial number 41032, with anti-clockwise rotor rotation, a contact breaker gap of .014 to 0.16 in. (.35 to .40 mm.), and a dwell angle of 60°±3°.
- What carburetter specifications apply?
- S.U. HIF4 carburetters, specification AUD 434, with a .090 in. (2.2 mm.) jet, AAU needle, and red piston spring.
- What is the correct idle speed and CO reading?
- Idle speed is 750 r.p.m. (fast idle 1,100 to 1,200 r.p.m.) and the exhaust gas analyser reading at idle should be 3 to 4.5% CO.
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