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Technical Items:

Vehicles:

Lucas Distributor Advance curves
and other stats 
and now  
Delco Remy Distributors as well  

 

     This list is the result of many hours of searching for proper settings during some of my past experimentation and troubleshooting efforts. Trying my best, I have not included anything here I could not verify from at least two different sources This list is in no way meant to be a declaration of true and proper configurations. Many different sources have been used to bring you this condensed list. Comments from list server archives, list chats, BBS archives, charts and tables from books, lecture notes, hands-on visual and physical inspections, and mechanic comments have all been brought together to try and define the variations in operating hardware used, originally, throughout the production history of the MGB, and now the Triumph Spitfire and GT6 models for the years identified here.
      I can not comment on the specs regarding any other model than those listed. Although these components may have been used on others, I have no reference and make no claims as to the accuracy of all this info.

    ... a comment regarding standard 'philosophy of use' for vacuum advance types.

       The early U.S. and U.K. vacuum units were configured to advance the timing when cruising which gives better economy and lower running temperatures. There have been (at least) three variations on the theme used to control emissions and pinging (some may call it pinking).

1. Vacuum advance was reduced at idle (to nothing) and when accelerating (depending on throttle opening) to eliminate pinging. This configuration picked up its vacuum from a tap directly on one of the carbs, thusly called 'ported' vacuum. This scheme usually had vacuum actuation that started to advance around 5-7 Hg/in. and would give a max. of around 10 degrees of vacuum actuated advance.
2.  The second major type usually started to advance at around 7-10 Hg/in of vacuum, giving a max. of around 5-10 degrees of vacuum advance. Most Smog equipped engines (later years) used this advance, where vacuum was applied at idle and reduced when accelerating.  The vacuum pickup was tapped directly from the intake manifold. Manifold controlled vac. units were usually used on distributors which gave a much greater total mechanical advance, then those using ported vacuum.
3.   The third was an intermediate type. Kind of a mix between the first two. The manifold fed the vacuum advance unit, with the advance curve only giving around 5-7 degree maximum.
and didn't start to have any effect until you let off the peddle a bit or were idling. These units were usually used with a distributor that mechanically started to advance at a much lower rpm range.

     This started as a MGB only list, but I've found that the MG Midget and Triumph Spitfire all use(d) the Lucas 25D4 distributor at one time or another. Therefore those distributors are now included (where I could verify the info) as well and are identified where appropriate.

 

if you've got one... not listed, let me know!

      Distributor chart with vacuum advance unit information
        and timing criteria (where available)

    4 Cylinder Lucas Models

model
years
used
engine code distributor
model # 
centrifugal advance in degrees @ rpm vac adv.
unit part#
Vac.
spec
vac
source
Static
timing
Dynamic
timing
? 1275cc
12CC/CE
Midget MkIII
Sprite MkIV
40819
(23D4)
0-3
@
600
6-12
@
1000
11-15
@
2000
- 22-26
@
5200
28-32
@
7000
none
attached
* * 7
BTDC
22 BTDC
@ 1200
? 18G, 18GA, 18GB,
  18GD, 18GG
40897
(HC)
(25D4)
4
@
600
6
@
700
9
@
900
15
@
1600
20
@
2200
- * 5.13.10 p 10 BTDC 14 BTDC
@ 600
? 18G, 18GA, 18GB,
  18GD, 18GG
40916
(LC)
(25D4)
6
@
600
8
@
800
9
@
1000
18
@
3000
24
@
4400
- * 4.10.12 p 10 BTDC 12 BTDC
@ 600
68-71 18GF, 18GH, 18GJ 40897
(LC)
(25D4)
10 @
400-
600
- 24 @
1500-
1750
- 30 +-2
@
3000
- 54411230 5.13.10 p 10 BTDC 20 BTDC
@ 1000
? 1098cc
Midget MkI
Sprite MkII
40919
(25D4)
0-1
@
800
2-6
@
1200
17-21
@
2000
19-23
@
1800
26-30
@
4400
30-34 @
6000
* 5.13.10 p 5
BTDC
8
BTDC
@ 600
? BMC special tune
C-BHA 44?
40943
(HC)
(25D4)
0-1
@
800
- - 16
@
2000
- 24
@
6400
* * * 12
BTDC
12
BTDC
@ 800
? - 41032
(25D4)
0-3
@
600
0-4
@
700
2-7
@
900
10-14
@
1600
17-21 @
2200
- * * * 10 BTDC 14 BTDC
@ 600
68-71 18GF, 18GH, 18GJ 41155
(HC)
(25D4)
10 @
400-
600
- - - 24 @
1500-
1750
30 +-2
@
3000
* * * 10 BTDC 20 BTDC
@ 1000
pre 71 1275cc
12CE/CD/V
Midget MkIII
Sprite MkIV
41198
41270

(HC)
(25D4)
0-1
@
600
2-6
@
800
4-8
@
1000
10-14
@
2000
20-24
@
3600
- * 5.8.3 p 7
BTDC
13
BTDC
@ 1200
post 71 1275cc
Midget MkIII
Sprite MkIV
41229
(25D4)
0-2
@
600
2-6
@
800
4-8
@
1000
10-14
@
2000
20-24
@
3600
- * 5.8.3 p 7
BTDC
13
BTDC
@ 1200
69 18?? 41264A
(24D4)
- - - - - - 54415625 5.11.8 p ? ?
pre 71 1275cc 12CD/CJ
Midget MkIII
Sprite MkIV
41271
(HC)
(25D4)
4
@
600
- - - 19 @
2300-
2500
30
@
4300
* 5.8.3 p 4
BTDC
10 BTDC
@ 1000
65-67 18V 41288
(HC)
(25D4)
0-6
@
600
4-9
@
700
7-11
@
900
13-17
@
1600
18-22 @
2200
- 54411985 5.13.10 p 10 BTDC 14 BTDC
@ 600
71 1275cc 12CD/CJ
Midget MkIII
Sprite MkIV
41229
(HC)
(25D4)
4
@
600
- - 19
@
2400
- 30
@
4300
* 5.8.3 p 4
BTDC
10 BTDC
@ 1000
67 18V 41290
(LC)
(25D4)
0-6 @
600
6-10
@
800
7-11
@
1000
- 16-20
@
3000
22-26 @
4400
54412170 5.11.7 p 10 BTDC 14 BTDC
@ 600
- 18V 41234
(HC)
(25D4)
0-1
@
600
2-6
@
1200
10-14
@
2200
20-24 @
3600
26-30 @
4500
28-32 @
6000
* * p 10 BTDC 14 BTDC
@ 600
71 18GK 41339
(LC)
(25D4)
- 10 @
900-
1100
- 24 @
2700-
2900
- 30 +- 2 @
4600
54414868 7.13.5 m 10 BTDC 15 BTDC
@ 1500
72 1275cc
12V
Midget MkIII
41369
(LC)
(25D4)
- - 15 @
1800-
2000
24
@
2700
- 36
@
4200
* 4.9.5 m T.D.C 9
BTDC
@ 1500
72 18V
584Z
585Z
41370
(25D4)
- - 20 @
1700-
2000
- 35 @
3300-
3900
41 +-2 @
4800
54423989 7.13.5 m 10 BTDC 16 BTDC
@ 1500
- 18V 41391
(LC)
(25D4)
0-1
@
600
2-6
@
1200
10-14
@
2200
20-24
@
3600
26-30
@
4500
28-32 @
6000
* * p 10 BTDC 14 BTDC
@ 600
73 1275cc
Midget MkIII
41400
(LC)
(25D4)
- - 15 @
1800-
2000
24
@
2700
- 36
@
4200
* 10.15.5 p T.D.C 9
BTDC
@ 1500
73-74 18V
672Z
673Z
41491
(LC)
(25D4)
- - 16 @
1800-
2250
- 32 @
3600-
4050
39 +- 2
@
4800
54425359 10.15.5 m 6 BTDC 12 BTDC
@ 1500
75-76 18V 41599
(45D4)
- - - - - * 54425516 10.15.5 m * 13 BTDC
@ 1500
77-80 18V 41593
(45D4)
- 2-6
@
1200
- - 26-30 @
4500
* * 5.13.10 p * 10 BTDC
@ 1500
76 Triumph
1500
41646 0-1
@
800
6
@
1500
8
@
1700
12@
3000
14
@
3500
* * 5.11.7
retard
m   2 ATDC
@ 800

   6 cylinder Lucas models

model
years
used
engine code distributor
model #
centrifugal advance in degrees @ rpm vac adv.
unit part#
Vac.
spec
vac
source
Static
timing
Dynamic
timing
69 MGC
entry courtesy Robert Edwards
41224
(25D6)
- - - - 18° max - 54418274 5.8.3 p 8°BTDC 20 BTDC
@ 1000
  2000 MkI 40967
(HC)
(25D6)
 -  - - 11-13
@
2100
 -  *  *
  2000 MkI 40975
(LC)
(25D6)
 -  - 15 @
2500
 -  *  *  *  *  *
  Vintesse 41168
9.5:1 comp
(22D6)
0°@
<500
0-1° @
600
5-9°@
1500
8-12°@
2300
15-19°@
4600
16-20°@
6400
* 6.20.22 * * *
  Vintesse 41182
7.0:1 comp
(22D6)
0-2°@
800
2-6°@
1100
15-19°@
2100
20-24°@
2400
25-29°@
4000
28-32°@
5000
* 4.20.22 * * *
  2.5 PI Mk1
41236
(25D6)
 - -  - -  - 11 @
3000
 *  *  *  *  *
  Vintesse 41273
(2206)
0-4°@
800
4-8°@
1200
10-14°@
1800
12-16°@
2000
16-20°@
3000
20-24°@
4000
* 2.16.26 * * *
  2000 Mk2
ME1
41314
(25D6)
 -  - 13 @ 2500  -  *  *  *  *  *
  2000 Mk2
ME50001
41378
(25D6)
 -  - 9 @
1800
- -  -  *  *  *  *  *
  2000 Mk2
ME92301
41452
(25D6)
 -  - 9 @
1800
- - -  *  *  *  *  *
  2000 Mk2
ML20001
41621
(25D6)
 - - - 11 @
2300
-  -  *  *  *  *  *
  2.5 PI MKII
MG1
41236
(25D6)
 -  -  - - 11 @
3000
 *  *  *  *  *
  2.5 PI MKII
MG75001
41502
(25D6)
-  - 13 @
1400
 - -  *  *  *  *  *
  2.5 PI MKII
MG82007
41543
(25D6)
 - 13 @
1500
-  *  *  *  *  *
  2.5 PI MKII
MG83620
41582
(25D6)
 -  - 13 @
1500
- -  *  *  *  *  *
  2500 TC
MM45
41536
(25D6)
 -  - 10 @
1400
-  *  *  *  *
  2500 TC
MM20001
41624
(25D6)
 - 7 @
1400
- 544286 5.10.8  * *  *
  2500 TC
Australian market
41654
(25D6)
- - 11 @
2000
- - - * * * *  *

     notes: 

1. (HC) = high compression  (LC) = low compression  
2. Vacuum spec numbers = start.end.total 
IE:  10.15.5  would start advancing at 10 Hg of vacuum, max adv. would be reached at 15 Hg ...for a total change of 5 degrees. 5 distributor degrees = 10 crankshaft degrees       Also note some spec 'spans' don't match the start/end 
3. vacuum source -  P=ported (carb tap)   M=manifold tap
4.  -  = no specification     *  = unknown data point

   4 cylinder Delco Remy models

sorry all...this 4 cyl table is just a place holder...you'll notice it's a copy of the Delco 6 cyl numbers from the tablew below
I need to hunt down the 4 cyl specs

model
years
used
engine code Delco
distributor
model #
centrifugal advance in degrees @ rpm vac adv.
unit part#
Vac.
spec
vac
source
Static
timing
Dynamic
timing
66 - GT6 MK I
2 liter 
7953291
(D202)
sp 213186
0-3@
900
7-11@
1650
9-13@
2400
12-16@
3600
15-19@ 
4800
18°@
5000
*        
vac. adv. spec degrees @
in/hg
0° 
0-3.8
starts
3.8-6.2

8.6-11.0
14°
12.2-14.6
18°
14.6-17.0
22°
20
adv & retard
module
       
68-70 GT6+ 
2 liter
7953547
(D204)
sp 308372
0 @
850
0-2.6@
1000
9.2-16@
1750
13.6-18.4@
2400
18.4-22.8@
3600
24-28@
5000
         
vac. adv. spec degrees @
in/hg

4-6
starts
4-6
- 8-12°
11
13-17°
14
22°
20
adv & retard
vac ports
with
vernier
knob
     
  GT6 MKII
2 liter
7953681
D200
sp 215511
0° @
400
- 7-11°@
1600
14-18°@
3200
16-21°@
3200
20-24°@
4400
         
vac. adv. spec degrees @
in/hg
-
starts
0-4°
4
6-10°
8
14-18°
13
14-18°
20
advance
module
with
vernier
knob
     
                           
                         
                           
                         
                           
                         
                           
                         
                           
                         
                           
                         

     6 cylinder Delco Remy models

model
years
used
engine code Delco
distributor
model #
centrifugal advance in degrees @ rpm vac adv.
unit part#
Vac.
spec
vac
source
Static
timing
Dynamic
timing
66 - GT6 MK I
2 liter 
7953291
(D202)
sp 213186
0-3@
900
7-11@
1650
9-13@
2400
12-16@
3600
15-19@ 
4800
18°@
5000
*        
vac. adv. spec degrees @
in/hg
0° 
0-3.8
starts
3.8-6.2

8.6-11.0
14°
12.2-14.6
18°
14.6-17.0
22°
20
adv & retard
module
       
68-70 GT6+ 
2 liter
7953547
(D204)
sp 308372
0 @
850
0-2.6@
1000
9.2-16@
1750
13.6-18.4@
2400
18.4-22.8@
3600
24-28@
5000
         
vac. adv. spec degrees @
in/hg

4-6
starts
4-6
- 8-12°
11
13-17°
14
22°
20
adv & retard
vac ports
with
vernier
knob
     
  GT6 MKII
2 liter
7953681
D200
sp 215511
0° @
400
- 7-11°@
1600
14-18°@
3200
16-21°@
3200
20-24°@
4400
         
vac. adv. spec degrees @
in/hg
-
starts
0-4°
4
6-10°
8
14-18°
13
14-18°
20
advance
module
with
vernier
knob
     
72-73 GT6 MKIII 7992127                      
                         
                           
                         
                           
                           

         Delco part numbers  79xxx= Delco p/n,   D2xx=model      sp xxx= Stanpart #

 

 

        ...update...   Lucas Tuning manual now on-line!

   OK guys and gals... if you've made it this far.... here's a little, SUPER RARE to acquire tidbit that will make it all make sense.

QUESTION?  So how do you 'tune' a Lucas distributor?   
Answer:   You read the Lucas Tuning Manual . This Acrobat PDF needs the Adobe Acrobat reader plug-in to view. This document goes into detail on how to determine, measure, and setup your   Lucas distributor to meet your needs.   

 


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last edited 12/06/09

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