View single post by normv
 Posted: 12-29-2006 01:21 pm
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normv



Joined: 08-07-2006
Location: Sydney, Australia
Posts: 46
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My trusty Jensen Manual shows the following centrifugal advance curves, in crankshaft degrees for the 3 types of distributors.

45D.4


RPM        Advance
550         0
1250       15 +/- 1
3550       18 +/- 1


25D.4 (early emission engine)
1000         0
1600         6.8
2200         13.6
2500         17 Max

Note
It list idle retard separately for stromberg cars as 3-5 at 6in of Hg and 5-7 at 10 in Hg prior to Eng. No 4803 This is the vacuum capsule on the side. This is vacuum retard NOT vacuum advance

 

Dellorto (I guess this means the 23D.4 as it list this for non emission engines)

BELOW 1000 No advance
1200             2
1400             4.4
1600             6.8
1800             9
2000             11.4
2200             13.6
2400             16
2500             17
 
Based on these figures if you were to use a 45D and simply remove the module and lock the base plate you could end up with a far to aggressive advance curve, this could be masked by reducing the static timing but I suggest you would loose performance , I have never tested this on a Dyno so I may be wrong and the engine may accept this, however I strongly suggest having 83% of your advance in by 1250 rpm is not ideal (assuming my trusty manuals figures are correct, it is a old Jensen parts & service book so I have no reason to disbelieve it)

Last edited on 12-29-2006 01:39 pm by normv