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Technical Information (MGB 21)

Distributor Specifications

Last Modified - 7/28/99

Eng #
Yr		 C.R. Distributor
Lucas #		 Vacuum Unit
Lucas #		 Max Vacuum Adv.
Dist. Degrees		 Max Centrifugal Adv.
Crank Degrees		 Ignition Timing
Crank Degrees		 Sparc Plug Type
and Gap		 Dwell
Deg.		 Gap New Dist. #
18G, 18GA
1963/65		 8.8:1 40897
25D4		 54411985
Ported		 Starts 5 hg in
Finishes 13 hg in
Advance 10		 18 - 22
@2200 rpm		 10 BTDC (static) N9YC 025° 57 - 63 014°
to
016°		 41427
18GB
1966/67		 8.8:1 141288
25D4		 54411985
Ported		 Starts 5 hg in
Finishes 13 hg in
Advance 10		 18 - 22
@2200 rpm		 10 BTDC (static) N9YC 025° 57 - 63 014°
to
016°		 41427
Late 1967
Low C.R.
 8.0:1 41290
25D4		 5441270
Ported		 Starts 7 hg in
Finishes 11 hg in
Advance 7		 22 - 26
@4400 rpm		 10 BTDC (static) N9YC 025° 57 - 63 014°
to
016°		 41427
18GF
1968		 8.8:1 41288
25D4		 54411985
Ported		 Starts 5 hg in
Finishes 13 hg in
Advance 10		 18 - 22
@2200 rpm		 20 BTDC @ 1000 rpm
Disconnect Vac		 N9YC 025° 57 - 63 014°
to
016°		 41427
18GH
1969		 8.8:1 41264
25D4		 54415625
Ported		 Starts 5 hg in
Finishes 11 hg in
Advance 8		 Unavailable 20 BTDC @ 1000 rpm
Disconnect Vac		 N9YC 025° 57 - 63 014°
to
016°		 41427
18GH
1970		 8.8:1 41288
25D4		 54411985
Ported		 Starts 5 hg in
Finishes 13 hg in
Advance 10		 18 - 22
@2200 rpm		 20 BTDC @ 1000 rpm
Disconnect Vac		 N9YC 025° 57 - 63 014°
to
016°		 41427
18GK
1971		 8.8:1 41339
25D4		 54414868
Manifold		 Starts 7 hg in
Finishes 13 hg in
Advance 5		 28 - 32
@4600 rpm		 16 BTDC @ 1500 rpm
Disconnect Vac		 N9YC 025° 57 - 63 014°
to
016°		 41427
(advise 41599)
18V584/585
1972		 8.8:1 41370
25D4		 54423989
Manifold		 Starts 7 hg in
Finishes 13 hg in
Advance 5		 39 - 43
@4800 rpm		 16 BTDC @ 1500 rpm
Disconnect Vac		 N9YC 025° 57 - 63 014°
to
016°		 41599
18V672/673
1973 to 1974½		 8.8:1
8.0:1		 41491
25D4		 54425359
Manifold		 Starts 10 hg in
Finishes 15 hg in
Advance 5		 37 - 41
@4800 rpm		 11 BTDC(early 1973
16 BTDC) @ 1500 rpm
Disconnect Vac		 N9YC 025° 57 - 63 014°
to
016°		 41599
18V797/798
1975
(Federal)		 8.0:1 41599
45D4		 54425516
Manifold		 Starts 10 hg in
Finishes 15 hg in
Advance 5		 34 - 38
@5000 rpm		 13 BTDC @ 1500 rpm
Disconnect Vac		 N9YC 035° 51 +/- 5 014°
to
016°
18G thru GH
1963/70		 8.8:1 41427
45D4		 54424170
Ported		 Starts 5 hg in
Finishes 13 hg in
Advance 10		 16 - 20
@4000 rpm		 (See above) N9YC 035° 51 +/- 5 014°
to
016°
Note: Do not hook up distributor #41427 or superseded distributor vacuum units directly to intake maniforld. Attach to rear carburetor port nipple only.
Eng #
Yr		 C.R. Distributor
Lucas #		 Vacuum Unit
Lucas #		 Max Vacuum Adv.
Dist. Degrees		 Max Centrifugal Adv.
Crank Degrees		 Ignition Timing
Crank Degrees		 Sparc Plug Type
and Gap		 Superseded to
Constant Energy Kit
Lucas #
18V797/798
1975 Cal		 8:1 41643
43DE4		 n. a. n. a. 33 - 37
@4500 rpm		 10 BTDC @ 1500 rpm N9YC 035° 60600719
18V801/802
1975 Fed/Cal		 8:1 41643
43DE4		 See note below See note below. 33 - 37
@4500 rpm		 10 BTDC @ 1500 rpm N9YC 035° 60600719
18V883/884
1977/79 Fed		 8:1 41693
43DE4		 *54429506
(old #54429339		 Starts 3 hg in
Finishes 11 hg in
Advance 12		 33 - 37
@4500 rpm		 10 BTDC @ 1500 rpm N9YC 035° 60600717
18V883/884
1977/79 Cal		 8:1 41695
43DE4		 *54429506
(old #54429339		 Starts 5 hg in
Finishes 11 hg in
Advance 7		 33 - 37
@4500 rpm		 10 BTDC @ 1500 rpm N9YC 035° 60600718
Note: Distributor 41643 (45DE4) could have a vacuum unit (part # unknown) attached, however the movable distributor base plate was pinned to prevent movement.
* Vacuum advance activated in 4th gear only.
18V797/798
1975 Cal
18V801/802
1976 Fed/Cal		 8:1 41815/A
43DM4		 See note below See note below 14 - 16
@2600 rpm		 10 BTDC @ 1500 rpm N9YC 035° 60600719
18V883/884
18V890/891
1977/79 Fed		 8:1 41813/A
45DM4		 *54428147 Starts 3 hg in
Finishes 11 hg in
Advance 12		 14 - 16
@2600 rpm		 10 BTDC @ 1500 rpm N9YC 035° 60600717
18V883/884
18V890/891
1977/79 Cal		 8:1 41814/A
45DM4		 *54428165 Starts 5 hg in
Finishes 11 hg in
Advance 7		 14 - 16
@2600 rpm		 10 BTDC @ 1500 rpm N9YC 035° 60600718
18V883/884
18V890/891
1980 Fed		 8:1 41851/A
45DM4		 *54426147 Starts 3 hg in
Finishes 11 hg in
Advance 12		 14 - 16
@2600 rpm		 10 BTDC @ 1500 rpm N9YC 035° Not applicable
(OEM fitment)
18V883/884
18V890/891
1980 Cal		 8:1 41853/A
45DM4		 *54424165 Starts 5 hg in
Finishes 11 hg in
Advance 12		 14 - 16
@2600 rpm		 10 BTDC @ 1500 rpm N9YC 035° Not applicable
(OEM fitment)
Note: Distributor 41643 (45DE4) could have a vacuum unit (part # unknown) attached, however the movable distributor base plate was pinned to prevent movement.
* Vacuum advance activated in 4th gear only.