Am I misunderstanding something here ? According to the XK140SE graph, if you add the 10 degrees to the curves, you get a total of 48 degrees, as it says static set at 10 degrees BTDC !?
I have a 1956 XK140MC (SE). The total advance including the ten degrees static is 38 degrees! Some later E Types had a higher total advance but NOT XK140’s. I installed a 123 Tune dissy that allows the advance to be set manually and found the advance and vacuum curves to be slightly different than original probably due to petrol changes or compression created by skimming the head a few times. I max at 36 degrees (26 in dissy and 10 on static). The vacuum is most important as the car usually drives with this operating. Note the MC -SE had a different dissy spec from the other cars and a different vacuum module. Viart’s book lists the correct numbers.
Yes, I understand how the 123 is programmed, I think as I have the blue tooth version. But, what I am saying from the attached picture of the graph is that it appears to start at 0 and goes up to about 38, but then says the static is set at 10 BTDC written in Red. So, appears to be in addition?
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This survey has some “inaccuracies” in the data as provided.
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The Distributors used for the Standard XK 140 and the XK 140 SE with 8:1 CR have been switched in this survey: the SE version with C type head has the Lucas 40199E distributor with GC 48 (the latter indicates the advance curve).
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The Lucas data I found show different values for the advance (in crank degrees) at various revs: see table below.
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According these data we arrive at a maximum ignition advance of about 40° (or better 38° ± 2°) including the 10 degree static advance. This is a very “normal” value.
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I would like to bring to your attention that the book you refer to is French, not Dutch. We cannot accept any responsibilities that result from possible inaccuracies in the book
Bob K.
Hi John…The Viart book has errors…i paid a lot of money for mine…now dont trust it for anything important…just use it as a guide and verify information from other sources…Steve
Bob, sorry about my mistake about being a Dutch book ! As Steve says there are many inaccuracies in that book. But, I am still amazed at the amount of advance in the last column for a 9/1 at 40-46 !
For some reason, I thought with higher compression, they were generally less advance.
The E Type 3.8 with 9/1 is not as aggressive as these figures.
Do you have the vacuum advance numbers to match these ?
I have a fully programmable Bluetooth 123 and want to try some other curves as an experiment?
My car is a 120FHC, but with 140 block and S Type head with two HD8’s.
Currently using the E Type curve, which work well.
Thanks
P.s. I like France - going there on Sunday for a week, for a bit of sun in the south ???
P.p.s my wife is half Dutch and lived in Amsterdam in 1980’s as a Ballet dancer.
John,
Far from an expert in high performance XK’s, I had a look at what Des Hamill refers to (in “How to power tune Jaguar XK engines”). He writes that 44 degree of total advance is the maximum one should not go over for all Jaguar XK engines. He also mentions, however, that a high performance XK engine should at least have 38 degree total advance as minimum. So these are apparently the border values.
I’ve mentioned the vacuum advance numbers at the bottom of the table. Don’t know whether you know what these figures stand for, but just to repeat: the first number indicates the vacuum (measured in lbs Mercury) where the unit starts to advance, second number is the under-pressure at which maximum vacuum advance is obtained, and the third number is the total number of degrees of ignition advance (in distributor degrees that is, so times 2 for crank degrees).
So as an example: Distributor 40199E uses vacuum unit Lucas 421720 (with numbers 7/18/12) where vacuum advance starts at 7" Hg under-pressure, obtains a maximum advance at 18" Hg whereby the advance reaches 12 distributor degrees as a maximum.
I understand that a vacuum unit is used to improve fuel economy, not to obtain better performance. That’s also why you’ll see in the last column of my table that the C-types (cars) didn’t have a vacuum unit at all.
Hope this is the info you needed.
PS. Have to be careful now as you probably know all the bad things about the Dutch via your wife…
Bob K.
no vac unit, or a closed off one was the norm for race applications…no cruising in a race !! pretty much WOT or brakes on…but on a street car …you “can” run no vac…but why…and a poorly operating vac can cause problems of missing, popping etc at cruise. 38 Degrees, all in from about 2800 to 3200rpm is a good range. When it comes in is adjustable with the mechanical advance springs…now who still has an old SUN distributor advance machine?
Nick
Some of you lot are really starting to get beyond the pale…
Its bad enough posting/ plagiarizing content from a copyrighted book without permission, let alone to then criticize it with sweeping unsubstantiated comments - so hardly an acceptable nor appropriate academic use and comment…
And its NOT a Dutch book and its NOT a French book…
Its a British Book as published by PJ Publishing in UK - thus its British. Also happens to be printed in China, such was the economic reality of book printing and distribution in 2010 and 2012
And the three main contributors to this book, are British (Paul Skilleter), Australian (me) and French (Viart), who shared the workload, with Skilleter contributing with the pre-plates Text and of course the Publishing, myself contributing the overwhelming majority of the pre-plates text and the Plates captions/comments and intellectual property/research and the majority of base photographs for the plates, with Viart’s main contribution being the actual development/production of his superb line drawing illustrations from actual base photos. And if you care to refer to page 454 you will note in the Acknowledgements, that of the 20 XK140s that contributed to the photos used on which Viart developed his line drawings, 16 were Australian, 2 were French, one from NZ and one from USA, and of those who otherwise contributed to this book, and were thus acknowledged, four are Australians, one British, one Swiss and one American - so not even one Dutchman in site!
The Distributor Advance Curve Plate 1-e2, as posted/plagiarized, that seems to be causing such indignant offence, I really cannot recall the source - I could check my immense development folders in researching/contributing to this book, but given the comments made, little point. The Distributors Data was my efforts, as obtained from both period Jaguar and Lucas factory references I have, and indeed when I did all this back in 2010 this all this new research detail and information was all a total revelation as was most of the books Plates content, all contributing to XK140 EXPLORED being awarded Automotive Book of the Year …
So 12 years later, after a lot of instant armchair expertise/plagiarism, we now have those who feel empowered to criticize… So Steve and Johnball - if you now seem to think of XK140 EXPLORED such to offer the throwaway line “there are many inaccuracies” could you please put up or shut up. I of course, 12 years later, am now also aware of a few errors, but if you really can substantiate your claim “there are many” - how about constructively giving me a list of what you think is wrong privately - regulars on this list are well aware that I am receptive and respond to constructive comment/questions if not nonsense comments nor unsubstantiated opinions . And if you really think you have wasted your money buying this book that’s easily fixed, nothing stopping you from selling it on - the current second hand price far exceeds its new book price on release, and indeed also the increased new book price for the REVISED REPRINT edition that demand for this book then justified …
But in the mean time, I look forward to seeing and reviewing your efforts at researching/ writing/ photographing/ illustrating and publishing your better book on XK140 Originality… - as there will be no revised/third edition of XK140 EXPLORED …
Hi Roger…Im not answering for everyone but just for my comments in the post above…my post said “The Viart book has errors”…i see nothing incorrect about that and was ment as advice to double check information…as for plagiarizing could you please explain…im no legal expert but the cover page in the 150 book does say no copying etc…“exept for reasonable use in connection with a review”…by posting the distributor curve diagram above is that not a review of the information printed…Thanks…Steve
Hello Roger, I am very sorry if I have caused offence or upset to anyone. That was not my intention at all. I just wanted an answer to my understanding of the graphs on the page. I did not realise I was plagiarising, just seemed an easy way to display my question, so it was clear to obtain the right answers from this very useful forum.
Roger,
Nobody will deny the tremendous help we got from “XK 140 Explored” during the restoration of our XK’s as the data (but even more the drawings) provide far better information than the SPC can ever achieve. But there are (were) “inaccuracies” in the book that (may) have been largely corrected in the 2nd edition.
But let’s talk “facts” and in this instance related to the subject of Ignition Curves. The page that John (illegally) copied (from the second edition, as the information is not shown in the first edition) shows a survey of data for the “standard” engine and the version with the improved “C-type” cylinder head, both with a CR of 8:1.
- The text refers to the Standard engine having Distributor Lucas 40199A to F which is incorrect. You also know that Lucas 40199A to D was never used on the XK 140, with a cap that differed from the later E or F versions. The Standard engine of course had Lucas 40436A. So the Lucas Distributor codes have been switched in Plate 1-e2 .
The Ignition data of every Distributor is defined by Lucas in the GC code or better the ECM number: for engines with the C-type head this is GC48 (ECM 440) and for the standard engine Lucas refers to GC48/1 (ECM 578) which is slightly different. I know you have access to the much more data than I have, like Lucas Test Data manual publication SB222. We apparently have different data regarding curve 440 and 578.
In Plate 1-e2 you also refer to a C-type Cylinder Head in combination with 2 H8 carburetors, but I assume that you meant H6 versions as the Distributor for the engine with 2 H8 carbs is totally different (Lucas 40293A) so not 40199 nor 40436. .
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You mention that the Standard engine has a static ignition timing of 8 degree BTDC but e.g. SB.156 as well as SB.165 refer to 10 degree BTDC for both the Standard and the C-type engine. Only the CR 7:1 engines use 8 degree BTDC timing.
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You show identical Vacuum advance data for the two distributors, but the Vacuum Units are different (Lucas 421720 for the Standard with 3/13/12 and Lucas 419066 for the version with C type head with 7/18/12).
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The ECM curve data I have access to, show that the typical difference between the C-type head version and the Standard version is that the advance curve starts later (900 to 1160 rpm) but the maximum advance is reached much earlier at 3200 rpm. For the Standard engine the advance starts at 320 rpm and maximum is only achieved at 5200 rpm (which might be an error). In any case, the springs in the distributor that control the weights (and thus the revs at which maximum advance is achieved) are different (416076/S versus 421721 for the later 40426A).
These are the “inaccuracies” I tried to highlight in my earlier respond to John. Some probably relate to misunderstandings and time problems during the preparations of the book between those who did the work, others are of a more “structural” character in particular related to the ignition curve data.
Hope you accept my explanation Roger.
Bob K.
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as a “non author” of much of anything except forum comments…it seems to me the original post and following comments are to determine distributor advance data and how it is achieved. So far, I have not seen it etched in stone by the hand of God. (I copied the page for my own use in learning about the distributor advance data: now I am nervously hoping I will not be served with a summons, a lawsuit and swat team raid.)
Nick
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I am concerned that allegations of “illegality” and “plagiarism” are being batted about too casualty. This is an international forum, so who knows what law would apply, but there is a generally recognized concept in copyright law known as the fair use doctrine. It holds that copyrighted material may be used, without creating a copyright violation, for educational purposes or criticism of the copyrighted material. This does not allow wholesale copying of a book or article, but it does generally allow copying of certain pages used for those purposes with proper attribution of the source of the information. I would say that most of the uses of copyrighted materials posted on JL are placed there to educate other listers or to raise questions or concerns the lister may have about the information. These uses generally fall within the fair use doctrine which is intended to allow for free discussion of copyrighted material without fear of violating copyrights. So you can’t just post and not attribute copyrighted materials, but you can post portions of copyrighted materials which are used to educate, criticize, and yes, even point out errors or omissions in the material without violating the author’s copyright.
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Bob,
You are assuming US copyright laws apply, what happens when a copyright owner resides in the UK, Europe or elsewhere. This is an international site so it may be a bit more complicated.
Matt
Edit: I re read your post and you are assuming nothing of the sort. My apologies.
If one of the authors is indicating that they would prefer we didn’t copy pages of their book to the internet maybe we should respect that. I do also find the graph of the timing a bit confusing as it starts at 0. Possibly the OP could just say on figure XX there seems to be a confusion and then describe it.
Matt
The concept of fair use has been recognized internationally since the Berne Convention of 1886. The point is that limited use and reproduction of copyrighted material is allowed for designated purposes, such as education, teaching, review and criticism. However, that would not allow a teacher, for instance, to copy an entire book just because his or her students are studying it. The use must be fair, and limited to the purposes intended, without interfering unreasonably with the exploitation rights of the copyright holder.
For our purposes, limited reproduction of a page or two accompanied by educational explanation, questions about the accuracy or completeness, or criticism of the contents are well within the bounds of the fair use doctrine. Were it otherwise, you could never have any reasonably detailed discussion of a copyrighted work without the express permission of the copyright holder.
I brought this up because I would hate to see the free exchange of information found throughout JL limited unnecessarily. At its best, JL is highly educational, information rich and a tremendous resource for those of us who are trying to learn all we can about these cars. If we could never refer to or post a page from a copyrighted work, that mission would be hindered significantly.
One caveat, always attribute the source of the information you are quoting or posting. Authors are entitled to full recognition for their work, whether you agree with it or not.
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Obviously I have caused a lot of controversy, which was not my intention as a retired XK owner sitting on the sofa, just trying to ask a question and clarify something that to me does not make sense, or I am misreading ?
I have apologised to RP. I have had good replies and advice about curves from others in this post, as what I am doing is trying different settings on the Bluetooth 123.
( currently running the 3.8 E type curve ) but next step is increasing max advance to 38 degrees as advised for an experiment.
Maybe the moderator should delete this whole post and if necessary expel me from this forum
John
John…I cant see anything wrong with your posts…keep calm and carry on…Steve
John, I think you missed my point. The type of inquiry you made is both appropriate and allowed. If inquiries such as yours were not allowed, this would be a poorer forum for sure.
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John,
Fully support the other comments that there was nothing wrong with your question for more data and showing the example of ignition curves in relation to that question.
For me, however, the question remains whether I could sufficiently help you in choosing the most appropriate curve or that the ignition data I provided for that purpose is incorrect and we should follow the information provided in Plate 1-e2 of the 2nd edition of Jaguar Xk 140 Explored.
Bob K.