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re:timing-some answers

To: Spitfires@autox.team.net
Subject: re:timing-some answers
From: Glenn Trunnell <trunnell@mindspring.com>
Date: Tue, 4 Apr 2000 23:18:28 -0400
Hi,

I was going to reply earlier to this thread, but I wanted to make sure that
my cam was installed correctly before I started sharing my experience, but
since it's come up so often I'm going to jump in anyway.  My car is a '76
with all the emissions installed, I currently have my timing set at 10 deg
btdc, with no vacuum advance installed.  I found that the vacuum advance
will indeed overadvance the spark at idle and the engine runs much more
roughly.  If I set the timing at 2 degrees atdc or even 10 deg btdc with
the advance installed the car is incredibly sluggish and has a top speed of
about 72 mph.  I understand the idea behind vacuum advance is to increase
economy while your'e cruising at part throttle, but the Spitfire is geared
so low that I don't think it is going to come into play very often.  Heres
some hard facts from the shop manual though:

 There are 4 distributors listed for the Spit

Triumph part no.        RKC0638 TKC1224 TKC2755 TKC3289
Lucas part no.          41449   41593   41646   41697
CEI replacement no.             41804   41805   41807

The Lucas EID distributors with the electronics on the side of the
distributor were replaced with the CEI units (with the seperate black
boxes) when they failed or were phased out.

Advance curves are as follows (degrees of crankshaft advance, distributor
advance will be 1/2 of the crank advance and the distributor RPM will also
be half the crank)

Centrifugal advance

RKC 0638
RPM (crankshaft)        Advance
600                     none
1100                    2 to 6
1400                    6 to 10
2000                    8 to 12
3200                    12 to 16

TKC 1224

850                     none
1200                    0 to 7
1600                    8 to 12
2600                    11 to 15
3200                    12 to 16
5000                    12 to 16

TKC 2755
800                     none
1500                    5.0 to 8.6
1700                    6.0 to 10.0
3000                    10.4 to 14.0
3500                    12.0 to 16.0

TKC 3289
800                     none
1200                    0 to 10
1500                    6 to 14
2200                    12 to 16
3500                    16 to 20

Vacuum Advance (inches of mercury vacuum)

RKC 0639
2.0                     none
3.0                     0 - 1
6.5                     1 - 6
8.5                     5 - 9
11.0                    9 - 13
18.0                    10 - 14

Vacuum Retard

TKC 1224

1.0                     none
15.0                    10 - 14
20.0                    10 - 14

Vacuum Retard

TKC 2755

3                       none
5                       1.5 - 3.0
7                       3.0 - 6.0
11                      6.0 - 12.0
15                      6.0 - 12.0

Vacuum Advance

TKC 3289

3.5                     none
5.0                     0 - 5
7.0                     5.0 - 13.0
9.0                     14.0 - 20.0
10.0                    16.0 - 24.0

Also if you have a CA Spit the numbers are:

Lucas EID# 41656                41698
Lucas CEI# 41804                41808

My '76 apparently came from the factory with the CEI style of ignition and
has the TKC 3289 distributor and I have checked it against these values and
found it to be accurate.

Good luck,

Glenn








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