Not one to give up, ive done some digging around and found some useful info I thought id share (sorry if its old hat and you already know this, but I found it interesting non the less)
the distributor I have bought for the bargain sum of £10 is (as was confirmed by jim) from a 1.3 escort, this is indicated by the part number 41982J, it would appear that 84SF 12100- is the generic part number for ford / Lucas distributors of this type and W7 54404307 is the Lucas distributor body casting number. http://www.flickr.com/photos/79991199@N07/7347344374/ 3788 indicates it was made in week 37 in 1988. Comparing this to two known XR2 distributors I have in my possession show part numbers as 42607 http://www.flickr.com/photos/79991199@N07/7347344910/ http://www.flickr.com/photos/79991199@N07/7162135095/ as confirmed here http://www.starchak.ca/tech/pdfs/lucas.pdf page 19 – 6th from the bottom. and on page 16 about 1/3 down shows the info for the 1.3 unit for comparison ……So it would appear this new distributor is unsuitable for my engine ……Or is it? After some research I found out that the only differing components between any two service numbers in the same distributor family are … 1 The cam with a stamped maximum mechanical advance figure 2 the Two small bob weight springs, 3 the vacuum advance diaphragm So opening up my new distributor shows a maximum mechanical advance of 13 degrees which equates to 26 degrees crankshaft advance http://www.flickr.com/photos/79991199@N07/7162134391/ (This would usually occur at 1500 distributor rpm = 3000 engine rpm Looking into both known XR2 distributor shows a maximum mechanical advance of 11 and 10.5 degrees which equates to 22 degrees crankshaft advance http://www.flickr.com/photos/79991199@N07/7162136413/ The difference of 4 degrees may or may not be pushing the limit of maximum advance even though factory advance curves are conservative as standard, Its beyond my know-how to jugde and i don’t want to be panicking each time I go over 3000rpm, so I decided to swap the cam and springs over as one unit though you could just swap either depending on what you want to achieve, being careful unhooking the springs so not to over stretch them http://www.flickr.com/photos/79991199@N07/7347345182/ Ive also calculated that 0.4mm on or off the cam stop equates to 1 degree of distributor advance or retard, so this can be fine tuned by filing down or building up by welding on a blob to suit, if so required The bob weights are the same across the distributor model range with the difference in advance curve characteristics being made via the springs, the photo below shows the difference in primary and secondary between the 1.3 version and the XR2 version http://www.flickr.com/photos/79991199@N07/7162138009/ The differing properties between spring types are as follows 1 Wire diameter; 2 Body diameter; 3 Number of coils; 4 Free length between end loops the biggest difference between the 1.3 springs and the xr2 springs is in the shape of the secondary advance spring which can be seen to have fewer coils and a slightly longer free length on the XR2 version, and using nothing more technical than my fingers I can tell that the XR2 secondary spring is stronger than the 1.3 spring. this gives the property of both a shallower and later secondary curve over the more gradual 1.3 curve, this is controlled by the there being much less free length in the 1.3 secondary spring meaning that it comes into tension much earlier in the advance curve. The primary spring is always in full control until the secondary spring engages. The point of engagement is determined by the free length of the secondary spring. all the info above is just based on what can be seen with the naked eye and confirmed by other sources, this is by no means any technical basis to start fiddling about with any aspect of the distributor without the aid of specialist measuring and testing equipment, which I don’t have. All I chose to do was transfer the 11 degree cam assembly and the springs to my “new” distributor body since neither part contains any wearing parts except the centre bush which has only ever moved 11 degrees so should be fine http://www.flickr.com/photos/79991199@N07/7162136635/ This gives me the base unit with the mechanical advance characteristics of an1.6 XR2 in both maximum advance and advance curve Onto the vacuum advance I’m struggling here to find any knowledge regarding these specific advance units, in earlier models of Lucas advance units, the 8 digit number is the Lucas part number and its well documented that the characteristics are stamped on the unit itself such as "5-7-4". These are the numbers that tell you the characteristics of the unit. The first number represents the vacuum point (in inches of mercury) at which the advance unit begins to operate. The second number gives the vacuum point at which the unit is at its full advance. The final number gives the total advance (in crankshaft degrees) for the unit. Unfortunately, although the units I have fitted to mine do have the 8 digit Lucas part number which does correspond correctly with both 1.3 and XR2 respectively, these particular units fitted to this series of distributor have the “other” numbering shown as “100 200 8 5” for the 1.3 and “160 230 8 6” for the XR2, ive no idea how to translate this into anything useful only the conformation that both my known old XR2 units have exactly the same numbering, so ill assume its right and fit that part, http://www.flickr.com/photos/79991199@N07/7347347498/ http://www.flickr.com/photos/79991199@N07/7347343822/ the only other thing I did notice was the word NINE stamped on the arm of the 1.3 unit and SIX stamped on the arm of the XR2 unit, but again ive found no useful way to translate this http://www.flickr.com/photos/79991199@N07/7162138655/ http://www.flickr.com/photos/79991199@N07/7162138901/ So with the advance cam / springs and vacuum diaphragm unit swapped over the 1.3 distributor becomes a 1.6 distributor. http://www.flickr.com/photos/79991199@N07/7162139201/ All in all im happy ive learned something I never knew before (amazing how the promise of a bargain can influence the desire to learn) and happy my engine is getting the sparks it needs when it needs them On Jun 4, 5:52 pm, jin <[email protected]> wrote: > hi all > got a bargian today in the shape of a brand new distributor in box > from a car boot sale > > id love to find out what it fits but ive no idea, > its a lucas unit with 2 fixing bolts at the base > the numbers are > > on the side body > > 84SF 12100-MA 8JB > 41982J 3788 > > under base mounting flange > > W7 > 54404307 > > the module has 84SF-12KO59AA on it > > any ideas? > any help much apreciated > > cheers -- You received this message because you are subscribed to the Google Groups "Quantum Owners Group" group. 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