The 'E' Type Forum

Does anybody know of a publication that explains how the original V12 engine works? I have the Repair Operations manual but that only details how to change things. I would like to understand the purpose of all those strange components and pipes.


Thanks

Hi John,
I would also be interested in a basic explanation of the engine management systems.

Ive read a lot on this excellent forum but would welcome a ‘ladybird book’ on how the vacuum system works. I’m aiming to put my USA spec to British spec when I get to that point in my restoration and I find myself getting lost when it comes to vacuum advance / retard etc etc.

If you do find a good source of basic information do let me know.
Cheers
Nick

Hi Both...as far as im aware there is no book that gives the type of inforation you are both looking for.....however now i,v said that someone will come up with one..... ....however just break everything down into its individual sections and refer to the service manual.....anything you dont understand post here with photos then im sure you will get replies.....Steve

Hello is this what you need?

JAGUAR V12 ENGINE - ITS DESIGN AND BACKGROUND. By Walter T. F. Hassan. Booklet produced by the Technical Administrative and Supervisory Section of the Amalgamated Union of Engineering Workers.

Paperback booklet. 52 pages. Illustrated with black and white drawings and photographs.

Great read. I have a copy.

Nigel

Hi Nigel,

I have seen a few references to this book and there is a copy on Amazon for £60 but I wasn't willing to spend that money without knowing how detailed it is. Does it explain the operation of the engine and all its component parts?

John

Nigel....how about posting a sample page....Steve

Probably as a result of the then recent launch of the XJS, the 1976/77 52 page A5 TASS booklet is a reduced combination of two earlier papers.
One presented by Walter Hassen - Director and Chief Engineer Power Units - to The Society of Automotive Engineers in January 1972 in Detroit and an earlier one by Harry Mundy (Hassan's deputy) to the Institution of Mechanical Engineers in London in October 1971. The last time I looked copies of both these papers were still available from these institutions - from memory IMechE charge about £12 and SAE about $30.
They all give a lot of information about the history, design and development of the V12 engine but other than details of the Stromberg carb in the Hassan paper, no details as far as I recall of the emission control paraphernalia which US cars were saddled with.


TASS booklet contents


Emission control kit is described in the Series 3 Press Release (4 pages) and in the US market car handbooks although there were a number of changes between 1971 and 1974. Happy to copy any info I have and post if forum rules allow.

TOP - 1971 non emission engine
BOTTOM 1973 emission control engine


Emission Control Kit

This diagram doesn't include the later EGR kit

The Institution of Mechanical Engineers version is available on their website as a .pdf for free. I am a member so that may be why it is free. It is a 15 page document.

Although it appears to be an interesting read it may not be exactly what thermojac is looking for.

Thank you all for your inputs.
What I am after is some publication that will give me an understanding the purpose of components serviced by the mass of pipes, tubes and wires e.g. I am currently servicing the car and when changing the air filter I notice that the temp sensor unit was broken. That then led me to taking off the filter housing where I noticed that the sensor has 2 hose connections. On my car both air filter sensors have only 1 tube, each going to the round black unit at the front of the housing. My question is: should there be a second tube from the sensors? Maybe between each unit to equalise pressure?

Hi the emissions set up depends on the model and year for where the connections go to the thermacs.

On my 1973 car the RH unit goes to RH servo further along the air trumpet and the other to a T off the thermionic valve and the LH unit goes to the rear induction manifold and the LH servo valve

In the workshop manual see 19.10.01 and 01/1 for alternative for RH to also directly take off vacuum from the RH front induction manifold.

The parts manual is also helpful 25.26 onwards to 25.32

Hope that helps
Nigel

Ps copy of the v12 book on the bay. No connection to seller

Thanks for your feedback Nigel which I found very usefull and I have also bought the book on Ebay.

Nick, I will let you know if it covers your requirements when I get it.

Thank you for all the contributions to this thread, all very useful and informative as always.

Best wishes

Nick

Nick, I purchased JAGUAR V12 ENGINE - ITS DESIGN AND BACKGROUND which was an interesting read but unfortunately it doesn't cover any of the operational stuff that we are after. The search continues

thermojac wrote: ↑

Mon Jan 11, 2021 6:41 pm

My question is: should there be a second tube from the sensors?

Here is pic of how it should (?) be connected, the OEM arrangement.


Each air box inlet has two openings, the front trumpet and the side flexible duct, the latter provides hot air from around the exhaust manifolds. In the air box inlet is a vacuum operated flap valve. When there is no vacuum the hot air opening is closed, all air is via the front trumpets. When there is full vacuum it is the front trumpets that are closed, all air is from around the exhaust manifolds.
The vacuum line from the inlet manifold to the flap valve actuator is via the “sensor” in the air box. I.e., there must be two vacuum lines connecting to the sensor, one to the intake manifold, the other to the flap valve actuator.
The “sensor” is a bimetallic (temperature controlled) valve, it bleeds off some vacuum to modulate the flap valve so that the mixture of air (from the two openings) is at a relatively constant temperature, so that optimum air-fuel ratio is maintained despite ambient extremes. (air density varies with temp.)

Attempted scientific experiment: Inside (the shed) is 33 degC, in the beer fridge is 5 degC, outside on the bricks is 48 degC.


Using one human sucker, modulation appears to occur within the range 35-45 degC.

You can stop looking for yr book, it doesn’t exist. Such was produced for the later (XJS HE) engines, i.e.
https://1drv.ms/b/s!AiSPBKa26IcchMxtWze ... g?e=32olEc
But nothing before and nothing after :(

lowact wrote: ↑

Mon Jan 25, 2021 3:03 am

Using one human sucker, modulation appears to occur within the range 35-45 degC.

Not a bad result Colin - this is what Jaguar said.

And all this matters for nothing as it is really not needed. My little sucker flaps have never worked and it has never had an impact on starting - car driven in UK/France/and Canberra Aust winters and never had an issue starting.

I think these are more to tick the boxes with authorities rather than do anything meaningful.

Garry

And all this matters for nothing as it is really not needed. My little sucker flaps have never worked and it has never had an impact on starting - car driven in UK/France/and Canberra Aust winters and never had an issue starting.

I think these are more to tick the boxes with authorities rather than do anything meaningful.

Garry

Ah, but Garry,

The satisfaction when you can make it work as designed! Also, since I fixed mine, I definitely seem able to push the choke in earlier than previously.

Regards,

Simon

Haha - I guess you are easily satisfied.

I’m not seeing it as a start thing, pointless trying to control air-fuel ratio when the choke is on? More of an all the time thing? No benefit of the flaps when ~40 degC is occurring without them, which may be most of the time? Otherwise just means you’d be that little bit more out of tune. Of course, if you are easily satisfied, just push slightly harder on the accelerator, V12E is good for that …