What is the ignition timing for the MGB 18V 581F/582F/583F engines?

Static ignition timing is 10° B.T.D.C. for both H.C. and L.C. engines; stroboscopic timing is 13° B.T.D.C. at 600 r.p.m.

What spark plugs and gap are specified?

Champion N9Y plugs with a gap of .024 to .026 in. (.625 to .66 mm.).

What are the valve rocker clearances?

.015 in. (.38 mm.) set cold, or .013 in. (.33 mm.) set hot.

What distributor and dwell angle are used?

A Lucas 25D4 distributor with a contact breaker gap of .014 to .016 in., anti-clockwise rotor rotation, and a dwell angle of 60°±3°.

What carburetter needle and spring are specified for the S.U. HS4?

Needle AAU with a Red piston spring and a .090 in. (2.2 mm.) jet.

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MGB 18V 581F/582F/583F Engine Tuning Data - Timing, Distributor, Carb Specs

MGB 18V 581F/582F/583F engine tuning data: timing, dwell, plug gap, carburetter specs, page 70

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MGB Engine Tuning Data for 18V 581F/582F/583F engines listing compression 9.0:1, idle 750-800 rpm, valve clearance .015 in cold, ignition timing 10 BTDC, Lucas 25D4 distributor and plug gaps.

AI caption September 2012 · Photo 40 of 101

This is page 70 of an MGB workshop manual (Engine Tuning Data 4, MGB Issue 3, ref. 83910), presenting complete engine tuning data for the 18V 581F, 18V 582F and 18V 583F engines. It lists engine specifications: 1798 c.c. (109.8 cu. in.) displacement, firing order 1-3-4-2, compression ratios of 9.0:1 (H.C.) and 8.0:1 (L.C.), nominal cranking pressure of 170 lbf./sq. in. at 275 r.p.m., idle speed 750–800 r.p.m., valve rocker clearances (.015 in. cold, .013 in. hot), and ignition timing (static 10° B.T.D.C., stroboscopic 13° B.T.D.C. at 600 r.p.m.). Distributor data covers the Lucas 25D4: contact breaker gap .014–.016 in., anti-clockwise rotor rotation, 60°±3° dwell, plus full centrifugal advance curves for serial numbers 41288 (H.C.) and 41290 (L.C.) and vacuum advance start/finish figures. Also specified are the Lucas HA12 ignition coil (3.1–3.5 ohms primary), Champion N9Y spark plugs gapped at .024–.026 in., S.U. HS4 carburetters with .090 in. jet, AAU needle and Red piston spring, and electrical components: Lucas 16ACR alternator, Lucas/Exide battery options, 12-volt negative earth, and Lucas 2M100 pre-engaged starter.

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Frequently asked questions

What is the ignition timing for the MGB 18V 581F/582F/583F engines?: Static ignition timing is 10° B.T.D.C. for both H.C. and L.C. engines; stroboscopic timing is 13° B.T.D.C. at 600 r.p.m.
What spark plugs and gap are specified?: Champion N9Y plugs with a gap of .024 to .026 in. (.625 to .66 mm.).
What are the valve rocker clearances?: .015 in. (.38 mm.) set cold, or .013 in. (.33 mm.) set hot.
What distributor and dwell angle are used?: A Lucas 25D4 distributor with a contact breaker gap of .014 to .016 in., anti-clockwise rotor rotation, and a dwell angle of 60°±3°.
What carburetter needle and spring are specified for the S.U. HS4?: Needle AAU with a Red piston spring and a .090 in. (2.2 mm.) jet.

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