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LewPalmer
USA
3242 Posts |
 Posted - 19/08/2023 : 00:48:40
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Some time ago, I saw an explanation of the letters and numbers in Lucas distributor model numbers. Does anyone have a copy of that explanation.
e.g. I know the "D" stands for distributor and the 4 or 6 means 4 or 6 cylinder, but what about the rest?
Lew Palmer
PA1169, NA0651 |
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Reinout
USA
223 Posts |
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tholden
United Kingdom
1638 Posts |
Posted - 21/08/2023 : 14:43:57
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Hi Lew
That Lucas technical book is very good but I would caution against assuming that the code numbers and letters on the distributor side plate represent what is actually inside. Some years ago I acquired a number of new old stock original DK4a distributors with various type markings. On examination some of the original markings had been carefully erased from what was clearly the original plate presumably during manufacture and some had been modified. Also with second hand distributors they may well have been modified over the years with different advance springs and the advance plate modified to give more or less advance.
There was a large variety of springs and several degrees of advance
fitted to this model of distributor depending on what type of car it was intended for originally.
When fitting one I therefore always start from scratch. Dismantle the unit and re bush the shaft bushes as necessary. Even the bushing of original ones was not always great. I then calculate the amount of advance set in the action plate and modify as necessary to what I consider to be the requirements of the engine it is to be fitted to.
There is then the springs and rate of advance to consider. I prefer to fit equal springs to give a straight line curve or line of advance. Frankly if you use equal standard medium strength springs this will give a good advance rate for cars such as a J or P MG. To complicate things with two different rate springs is not necessary on our cars and is unlikely to improve performance in the small rev range they will operate in. With other models you may need to experiment further to get the rate just right for your engine.
There are dozens of options and given that fuels and spark plugs have changed dramatically in the last 70 years there is no one correct solution today so in my view the original distributor markings have little relevance now.
Now if I had one of those distributor test machines that the brilliant Don Mc Loughlin founder of Aldon Automotive showed me many years ago I could check out and set up individual distributors easily.
For those that do not have such a machine I would suggest purchasing a copy of the excellent book " How to Build and Power Tune Distributor Type Ignition Systems" by Des Hammil. My copy is rather ancient but it is still available on Ebay and Amazon.
Terry
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LewPalmer
USA
3242 Posts |
Posted - 21/08/2023 : 15:49:31
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Thanks, Reinout. That's it.
Terry, I agree. I have purchased several distributors for my NA. Technically, I am supposed to have a DQH6A, but one of my purchases has that exact model on the tag, but it has no advance mechanism - not even any room for one as the body is about half the normal height.
Lew Palmer
PA1169, NA0651 |
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Drolshagen
Germany
669 Posts |
Posted - 21/08/2023 : 17:20:44
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Hi Lew,
may be following can help you
cheers
Carl
J2 4362
L2 2036 |
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LewPalmer
USA
3242 Posts |
Posted - 21/08/2023 : 18:23:19
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Thanks, Carl, but that's the same info that Reinout sent - page 23.
Lew Palmer
PA1169, NA0651 |
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