POST 34 - CONVERSION TO HYDRAULIC CLUTCH - OR NOT

Hydraulic - V - Mechanical Clutch Operation
I had every intention of converting the clutch from mechanical to hydraulic operation and to that end purchased a 150 slave cylinder with mounting bracket. The bracket did not exactly fit the 120 bell housing and required a fair bit of fettling to get the push rod moving at something like the correct angles when moving the clutch operating lever. It did eventually all line up reasonably well but looked like a bodge, as if it was never meant to be there.

This just doesn't look right

To resolve the master cylinder issue, I had considered fitting a complete new pedal box but at 5 foot 8 inches tall, and with bucket seats fitted, the original pedal location, for me, should be just about right.  The current trend to move the pedals forward a couple of inches, which a new pedal box would allow, might increase the cars future saleability.  (I remember reading somewhere that tall men are generally richer than short men).  Having to put blocks on the pedals as my dad did on my first bike seems like a naff idea, and I am after all building this car for me. 
So, having acquired a likely master cylinder some time back, I set about looking at how to best utilise it in conjunction with the existing pedal arrangement.  With the new slave cylinder fitted, there is no longer a place for the end of the clutch operating shaft.  This can possibly be resolved by making up a substantial plate with some form of bearing for the remote end of the cut down shaft.  Also, the operating lever will need to be relocated with a new key way machined into the shaft and the chassis will need some holes drilled to attach the plate.  It's all getting horribly complicated.

Time to ask the obvious question.

Why exactly do I want to operate the clutch hydraulically?
Whilst the mechanical arrangement has lots of parts, it is in fact reassuringly simple with very little if anything that could fail catastrophically. 

As usual with Jaguar design, many parts make up the clutch
operating mechanism.  Note washer in bottom right hand
corner and see "whats that clicking noise" below.

My 140 has exactly the same arrangement and I have never thought it heavy to operate.  With a 9.5 inch E Type pressure plate it will be lighter anyway.  No seals to worry about and no hoses to split.  Nothing to bleed and no fluid to periodically check and top up and wonder where it went.  On the other hand, the idea of having a shaft mounted between one fixed point, the chassis, and one vibrating point, the engine, can not in principle be good.

Very odd ware characteristics on end of clutch shaft, bearing and cup.

Looking at the wear patterns on the bell housing end of the shaft, spherical bronze bearing and cup, it clearly has not had a happy life.  Never the less, it was still working (as far as I could tell) after fifteen years of hard use and neglect and a further forty five years of miserable lonely inactivity.
On balance, it's clear that the right and proper thing to do is to restore it to its original mechanical state, rotating happily in new bronze bushes, carefully lapped into their cups and then lubricated with very best grease that money can buy.    Why did I ever think it a good scheme to usurp this fine piece of engineering with masters, slaves and their vile corrosive hydraulic fluid.  Whilst on a roll so to speak, perhaps I should consider upgrading the braking system with cables, rods and levers!
My good friend Richard Cook who fortunately understands my passion for such things, machines the badly worn end of the shaft and fits a sleeve making it as good as new.  Medical science has some catching up to do.

Resplendent with new sleeve, bush and cup.  What more could
an original clutch operating shaft want?

So I guess the only remaining question is :
Is there anyone out there who would like to buy a brand new Tilton 74-700  7/10" Master cylinder kit complete with remote mounting kit, hoses and clips and an XK150 slave cylinder with slightly butchered mounting bracket.

Mr Happy Shaft back home and back in employment.

Tilton Master Cylinder - Heading for EBay

Whats that clicking noise?
Pushing the clutch pedal on my 140 would often but not always produce a light clicking noise which could be felt through the pedal. As it came and went, I was never too concerned.  Last winter I decided to investigate and removed the whole clutch shaft assembly, cleaned it, replaced the bearings, "O" rings etc. and re-assembled it. The result was a satisfying silence. The noise had gone, for about a week, then it re-appeared. With assistance and a listening tube, I established that the noise emanated from inside the chassis. The end of the spring had worn and worked its way into the chassis side, sometimes catching and winding up then twanging free with the shaft motion. It seemed strange that nothing was fitted to the shaft to stop this happening.  About this time I bought Bernard Viarts amazing book - Jaguar XK140 Explored.

Bernard Viarts amazing book on the 140 and a typical drawing.
A 120 edition is hopefully due out later this year

The superb drawing of the clutch shaft assembly, although for a left hand drive car, shows a washer (C3295) between the spring and the chassis.  Definitely not present on my car and very unhelpfully not shown on plate F of my Jaguar parts manual.  I found a suitable washer and did a trial fit.  Removing the shaft to fit the woodruff keys, the washer fell off the end and into the chassis.  My 'magnet on a stick' fished around inside the chassis and was carefully removed with not one, but two washers attached!   It doesn't matter which way you remove the shaft, the washer will most likely fall off into the chassis.  Consequently, you would never know it was ever there, and the parts manual nicely confirms its non existence.

Prop Shaft angle
The new prop shaft to fit the T5 box finally arrived and was fitted, but the angles required by the UJ's to meet the diff seemed a bit severe. The reason of course was that the re-tempered springs are sitting high with very little weight to settle them. I calculate that a full fuel tank, rear part of the body with boot contents and the best part of two passengers would approximate to 200Kg's.
Fortunately I have to hand a pallet of coaxial cable with each 250 Mtr reel weighing about 11Kg. Stacking 18 reels over the axle settles the springs very nicely and makes the prop shaft angles acceptable.

18 reels of coaxial cable approximately equates to the back half
of the body, a full tank of fuel and a couple of big lads.
Springs and prop shaft angle now look about right

Cylinder Head and Gasket - Final solution
Following on from my previous post and the problem of fitting the camshaft sprockets, assuming my calculations are correct, it looks like I will have to settle for a thinner gasket and a compression ratio of 9:1.   Rob Beere supplied another Cometic composite gasket, this time 60 thou, and it all goes back together without a hitch.

Sprockets fit easily to cams with gasket reduced to 60 thou.
Why has the head got this odd double stamped engine number?
See post 10 for the most probable explanation.

It's still a puzzle as to why, with only 18 thou being skimmed of the head the chamber volume was reduced by around 10%.  One possible explanation could be the depth of the new valve seats and the profile of the valve top, but I don't have another head to compare.  Another explanation could just be that my calculations are rubbish.

Could valve seat depth and profile be responsible to reduced chamber volume?

As I intend to use a 123 Ignition set up with programmable advance curves via USB port and lap top, I am hoping that this is all a bit less critical and I will have the opportunity to tweak the timing to accommodate the higher ratio. With 99 octane costing around £1.40 a litre (that's around $8.30 a US Gallon to you hard done by American boys) and not available at many petrol stations, you can see why it would be good to be able to use 95 octane.  I know that the theory says 99 gives you a bigger bang so you should use less of it, but in my experience it seems to make little if any difference.

Miscellany - related topics

Beamish Rally
A couple of weeks after this wonderful day out, I received a phone call from Mr George Jolly, the event organiser to tell me I came first out of around 150 entrants.  Totally unaccustomed to winning anything ever, this came as very nice surprise.  However, the actual credit for the win must go to navigator Tony Firth, who has an encyclopedic knowledge and recall of all things relating to old motors, no doubt giving us a super high score for the quiz part of the rally. 

Stuffed again by the weather men.
The biggest classic car event in North East England at Newby Hall near Ripon was cancelled after a "pitch inspection" four days prior to the event.  No doubt the forecast of a further twenty odd hours of heavy rain over the next three days would have played some part in the decision.  Apart from the occasional light shower on Friday, the forecast was around 95% wrong.

Next Post beginning of August

POST 33 - JULY 2012 - PROGRESS 1 - FUN 5

Cylinder Head, Compression Ratios and Gasket Choice

After a few hiccups relating to shims, I finally feel happy with my cylinder head assembly.  The waterways have been welded up and re-machined with 18 thou skimmed off to clean it up.  Inlet and exhaust faces have had a light skim to ensure absolute flatness.  New hardened seats and phosphor bronze guides have been fitted along with stainless steel valves and new springs.  The camshafts were in excellent order and just needed a light clean up and new bearings.  So all in all, a pretty comprehensive head overhall.

Time to decide on the ideal compression ratio and consequent gasket thickness, with a wide range available, from the original 15 thou, all the way up to special order composite items at 130 thou.  First I need to re-establish head chamber volume after machining.  I did this exercise previously by using liquid paraffin, establishing its specific gravity and weighing it on letter scales.  All chambers came out at between 105 and 107cc which I thought a little high but surprisingly the C/R came out about correct at 8:1 on my spread sheet.

This time I did the same exersise using a 100cc burette and water (as I subsequently discovered that the SG of liquid paraffin is not absolute) and they came out at around 95cc. 

No more make shift measuring.  A proper burette and a clear DVD
stuck down with a smear of grease.  The head was first set exactly
level to avoid surface tension bubbles under the plastic.

To acheive my ideal 8.5:1 C/R my spread sheet indicated that I required a gasket of around 90 thou and Rob Beere racing had a Cometic 98 thou composite item in stock.

Delivered the following day it was fitted and the head duly torque'd down to 60 foot pounds 

PROBLEM

No matter how hard I tried, and how carefully I positioned the tensioner, one or the other sprockets would not go over the end of the camshaft indicating too thick a gasket or too short a chain.   I had, as a matter of course previously checked the chain length against the original with no discernable difference.  The shortfall was nothing more than at most a frustrating millimeter or so, indicating a gasket thickness reduction of half that (as the chain goes around two sprockets) - around 20 thou.  Again consulting my spread sheet, going down to 60 thou would produce a C/R of just over 9:1 not my absolute ideal but easily acceptable.

More on the final outcome in my next post.

Dynalite - an alternator that looks like a dynamo

I spent quite a while researching this and finally concluded that it was a worthwhile upgrade, producing a maximum of 40 amps and wieghing 10 pounds (the original Dynamo wieghs 19).   The alternative was to buy the bracket and pulley plus a cheap scrap-yard alternator.  It would doubtless have saved a considerable sum but the essential pulley only comes as part of an upgrade kit, with no supplier prepared to sell it on its own. 

The dimensions of the Dynalite are identical to the dynamo and I added the finishing touch by fixing the original  "Lucas Special Equipment" plate and faux rivets to the body.

Adding the Lucas plate has probably voided the guarantee!

Morgans Diary

Anyone wanting to know what's happening on the Classic Car scene in the North of England buys Morgans Diary in February, which lists pretty comprehensively every event for the year.  It's also used by organisers to avoid clashes with other events.  So how did this super useful publication come about?

Many years ago before the internet, Mr Morgan started to keep a list of dates for Classic Car events, Auto-jumbles etc. in the North of England and word got around that he was the man to ask if you were planning an event or looking for something to do at the weekend.  After a while he formalised his lists into a small printed publication and sold copies, with the proceeds going to charity - Good Bloke. 

It's popularity grew to the point where it was almost a full time job for a single individual and Mr Morgan decided he had done his bit and it was time for someone else to take up the reins.

Step up to the plate Tony Raylor and York Vikings Rotary Club - with many volunteer hands to make light work of the job.  Morgans Diary (Now officially called Morgans Guide to Historic and Classic Vehicle Events) has raised to date an amazing £150,000 for charity and recently handed over £10,000 to The Great North Air Ambulance.

For a publicity shot they needed an appropriate Classic car as a link and as I had the time and live reasonably close to Tees valley Airport I was both happy and honoured to oblige.

http://www.morgansyearbook.co.uk/

Rotary Chairman Martin Kirby hands over a Cheque for £10,000
to Great North Air Ambulance Paramedic Dave Allanby

Raby Castle - JDC Area 11
The lack of overall progress in the past two weeks has mainly been down to a very busy schedule of shows and trips with no work taking place over any weekends in June.
June 24th was JDC Area 11's main annual event at Raby Castle.  As an added attraction we decided to take my rolling chassis along.  It created a huge amount of interest and it was gratifying to hear dads explaining to their kids the purpose and function of the various parts, normally covered up.

120 Rolling Chassis on display at Raby Castle  June 24th

Also on display were a couple of couple of cars borrowed from Jaguar Heritage and used in films,
the Mike Myres Union Flag painted "Shaguar" and an XK8 from the Bond Movie, Die Another Day, with a Gatling type gun mounted on the back.

Couldn't miss this photo opportunity

As I wasn't going to get the chassis back until the following Wednesday I took the opportunity to freshen up my workshop and give the floor a coat of paint.

Mr G M wisely removed his shoes before entering.

Safely back home.  Shame about the sheep Sh--- in the tyre treads

The following Saturday JDC organised a visit to the North Yorks Moors Railway Workshops at Grosmont which involved a drive through some of Englands most deserted roads, with fantastic moorland views.   Just as well I forgot to take my camera.  This post would otherwise be never ending with pictures of hills and Steam Trains.

Hob Hole near Westerdale - Superb "exactly as shot" composition
 by Geoff Mansfield with only a few seconds to set up.

Next post mid July

POST 32 - JUNE 2012 - Chassis Mod to accommodate T5 Box

Spigot bush 
Splitting the engine and gearbox after the trial fit, I notice that the assembly grease on the end of the gearbox main shaft is only displaced around 15mm.   This explains why they supplied a new spigot bush (yet to be fitted) with the T5 box.  Fellow XK enthusiast Tony Hamnet explains - the T5 main shaft is slightly shorter than the Moss item and is also moved back 10mm by the box to bell housing conversion plate.  The new bush effectively extends the bearing surface forward by around 15mm.

New Spigot Bush extends bearing surface forwards around 15mm.

Re. my previous post and the question - what is the purpose of the T5 box additional cables and socket.  Dan at Classic Jaguar tells me they are connected to an internal switch which is only closed in the neutral position.  If placed in series with the starter solenoid feed, it means that the car cannot be started in gear. 

Modifying the chassis to accept the T5 Gearbox
With the engine bottom half and gearbox now permanently together, I suspend them over the chassis with the front engine mounts vertically aligned in order to establish what needs to be done to accommodate the gearbox rear mounting pad. 

Hate to change the chassis cross member but will no doubt consider
it worthwhile when snicking through the T5 box next summer.

The existing mounting plate needs to be removed and the vertical support plates cut back to around 35mm.  A section 8.5" wide, 30mm in and 50mm deep at the sides is the removed from the top front edge of the cross member.  I also take out a small "V" top centre to allow for the gearbox central web.

Section cut out ready to take new metal.
I really must give those shoes a polish.

Next I make up the gearbox support plate.  This is very simply two lengths of 2mm thick angle.  The top piece to fill the hole is 50/50mm by 8.5" with the vertical section cut to match the shape of the cross member, plus the "V" for the web.  The bottom piece is 35/35mm by 8.0" and will fit between the remains of the vertical supports and provide additional strength. 

Apologies for the measurement mixture but as an imperial boy and a metric man it works for me.

Simple to make but very strong - filler and support

I can't believe this is a casting error so can someone tell me
why the mounting plate is around 10 degrees from horizontal?

Another intriguing anomaly is that the gearbox mounting is at an angle of 10 degrees from horizontal. As American muscle cars use symmetrical V8's, this seems very strange. It also means that the nearside bobbin needs to be 13mm higher than the offside. Getting this right was very time consuming.

Bobbins set to allow for angle with tapered washers.  Note essential
extra long threads on bobbins to clear 15mm thick mounting.

Neatly welded in place (not by me!) with 2mm plate filling in
the sides.  Fine texture stone-guard and two pack satin finish
all made good.

Finally in place.  Output shaft centre is 2" above top of cross
member as per original moss box .

In some ways this turned out to be more straightforward than I expected but did take some time to get exactly right.  The mounting is very strong especially with the bottom piece of angle welded to the front face of the chassis cross member.   This will hopefully be helpful for others in the future.

Classics on show Stokesley - June 16th
My home town held its first Classic Car Show on Saturday 16th June, organised by the local Rotarians.  In spite of a rather poor weather forecast, a turnout of over 100 classics enjoyed an extremely good atmosphere with many old friends meeting up and enjoying the day.

A corner of the large show ground swallows up the 100 plus
classics turning up to the very first Stokesley "Classics on Show"
England's Green and Pleasant Land at its best.

Almost all Classic shows in the UK are held in fairly isolated locations in the grounds of Castles or Country houses making the participants a somewhat captive audience.   Fine for us hardcore enthusiasts, but it does understandably discourage wives and families from joining us.  This venue is a large traditional and well established English show field within a few minutes walk of a lovely old Yorkshire market town.  Interesting shops, pubs, restaurants and the picturesque River Leven offer some respite for those less involved.
Just a matter of time I think, before the list of world class venues reads - Pebble Beach,  Carmel, Amelia Island,  Stokesley, Villa d'Este,  Salon Prive'.
Congratulations and thanks to the organisers for a very enjoyable day.

Beamish Run - June 17th
'The Beamish' as it is generally known, is a 144 mile County Durham based reliability trial for vehicles manufactured before the end of 1955 (very strict).  My 140 fixed head just qualifies and is possibly the youngest of the 160 cars participating this year.  Early car manufacturers used a number of notably difficult routes, with streams to ford, long and steep gradients to ascend / descend, often with very sharp bends.  The Beamish Connects many of these trial routes together and makes for an exhilarating full days rally.  In addition to completing the course, points are also scored by answering a series of often eclectic motor related questions at each check point.  A superb day out in some of England's most beautiful countryside and loads of fun.

End of day.  XK140 and super rare Swallow Dorreti. 
Note standard British Post War Male hands in pockets stance.

XK120 came all the way from the Isle of Man

Not always green and pleasant.  I wonder how many seconds
this particular rash of wind turbines will add to the life of the earth.
As far as I know there is not a collective noun for wind turbines so
'rash' seems appropriate, as it is commonly used for unpleasant
  things that suddenly appear.

Grandsons "Chicken Pox Charlie" (left) and "The Fredster"
help with the Monday morning clean up.

Thanks Uncle Dan
http://www.classicjaguar.com/

Next Post beginning of July

POST 31 - JUNE 2012 - CARBS, CLUTCH & GEARBOX

There always seems to be a reason why it's not possible to completely finish some particular part of this project and it's very frustrating.  Jumping to a new area of work before finishing the current one means lots of loose ends, but that seems to be the nature of it, and whilst I try to plan ahead, it never seems to quite work out.

 

 

Carburettor Rebuild
Whilst awaiting completion of machining of my Cylinder Head, rebuilding the carbs seemed to be an ideal fill in job. The spindles and main body which usually wear and allow air leaks are actually in very good condition, so its mainly a strip, clean and re-assemble exercise.
In a very senior moment whilst rebuilding my 140, I forgot that I had already bought a pair of HD6 service kits and ordered another pair (such lapses of memory do not bode well for the future I hear you say) so my only cost should be time. It all went rather well until I attempted to remove the fuel inlet union on the RH float chamber and a hairline crack appeared in the top. Burlen were out of stock, so that's another 99% completed job.

Doing one carb at a time means you can always look at the other
when you forget how it all goes back together.

All done.  Just need a new top for one float chamber.

Boot Lid
The £250 boot lid wood frame arrived on time and as requested was supplied disassembled. I would have to say, the quality of workmanship is quite exceptional. It all went together perfectly and I attached the various metal parts in order to do a trial fit. The overall size and shape looks about right and I am just awaiting the bodywork guys to fit the locking bar keeps to the body and tweak the fit.
I then need to dismantle it, paint all the steel parts with red oxide, and rebuild it inside the aluminium skin.  More on this in a future post.

Clutch shaft and fork assembly
The taper pin which engages the clutch fork on its operating shaft was still doing its job but came out in three pieces, I would think the inevitable consequence of fitting a tapered pin into a parallel hole.  The replacement item was over size but has a parallel shank so I needed to first clean up the hole in the shaft, then have the pin turned down to make it an interference fit.
The shaft bushes were also quite worn as was the carbon thrust plate on the fork, so both were replaced, the latter with a Coventry Auto Components upgraded item.

Old taper pin came out in three pieces.  New one is parallel

 Clutch shaft bushes - easy to slip in a ten thou gauge

New thrust, pins and bushes.  Bolt wiring technique is improving.

Clutch installation
With all these minor jobs completed, its time to fit the flywheel, clutch plate and cover, but first I need to ensure that the clutch plate is centrally aligned against the flywheel.  A half inch brass drift makes the ideal base for the alignment tool.  Add an old socket and some insulation tape to make up the clutch plate spline ID - perfect.

Heath Robinson clutch alignment tool
Each wrap of PVC tape increases the OD by around 4 thou
so with care, it's possible to make this a very precise device

Clutch plate and cover is now a 9.5 inch E Type spec item with
flywheel drilled and tapped to suit

Tremec Five Speed Gearbox
When I restored my 140 fixed head, I fitted a Tremec T5 gearbox. Its a superb box with a great shift action so it was an obvious choice for the 120, especially as overdrive is not an option.  It was supplied with a conversion plate to mate it to the XK bell housing - all quite straight forward.

Scary moment.  will these much modified parts really fit together?

Yes - with the usual bit of "waggling" its goes together nicely

The Tremec T5 box differs from my previous one in that it has an extra cable and plug coming from the top plate - clearly visible in the above picture, but no one seems to have a clue what its for - any ideas?
 The downside of fitting the Tremec box to a 120 is that I will need to remove some steel from the main chassis cross member and fabricate some form of rear mounting bracket.  I will cover this in detail in my next post.

Next Post - Mid June

POST 30 - MAY 2012 - FUEL PUMP RECON

Another infill job is required whilst waiting for the return of the cylinder head and ash frame for the boot lid.  Having piped up the brake system, the next logical job has to be the the fuel line and pump.  The original pipes appear to be copper and whilst covered in all manner of crud, they are in excellent condition with undamaged unions.  The SU fuel pump however is in a pretty bad way.  It just looks awful and stinks of stale petrol / old paint and a 12 Volt supply across it met with an unsurprising silence.

Original SU High Capacity (Type LCS) pump - dirty and dead

I can easily replace it by plumbing in a modern Facet pump but there are other considerations:

• The pipe work and unions would need some surgery with naff looking bits of rubber hose and clips.
• There is something reassuring about the click - click - click of an SU fuel pump.
• Depending upon the precise volume, tone and frequency of the "click" a whole range of fuel line faults can be diagnosed.
• The critical path / weakness, the points can now be replaced with a solid state upgrade kit.  The downside to this is that you will no longer have the satisfaction of hearing the result of a good whack.
• It is still possible to telephone Burlen, the main UK supplier of parts and have a proper technical conversation with a knowledgeable human being. 
• I think concours judges should ask for the ignition to be turned on and then deduct a few points for silence or some other inappropriate noise.

Apart from the points under the black plastic cover, the innards and workings of SU fuel pumps have always been a bit mysterious, but with nothing to lose, it only takes around twenty minutes to have it totally dismantled.

Fully dismantled - note 11 brass spherical rollers.  Also note
the amount of very fine black muck on the inlet cover plate
compared to the relatively clean outlet side cover plate

Diaphragm / Bronze rod, brass spherical rollers and return spring

The detailed description of it's operation in the Factory Workshop Manual, coupled with all the bits laid out in front of me eventually unravel the mystery.   The only electrical part of the pump that will be retained is the magnetic coil embedded in the iron core body.  Loosely holding the diaphragm and bronze rod within the central hole in the magnetic core, and momentarily applying 12 volts produces an immediate upward movement and familiar click.

For future reference
A known working magnetic coil measures around 4 ohms

A full service kit and negative earth solid state PCB  are ordered from Burlen.  The end plates and body are painted and all other parts cleaned.   A large amount of compacted fine black muck was removed from the inlet chamber containing the brass gauze filter so this clearly dose a sterling job.

The service kit when it arrives is inspected and I find the bronze rod attached to the diaphragm is around half an inch shorter than the original.  It transpires that this version of pump has a long and short body.  More return postage costs!  Also, the kit contains a new rocker / point assembly which will not be required.

Ready for re-assembly.  Parts on the bottom row are not required

The diaphragm assembly is held central in it's housing by 11 (odd number ?) spherical rollers (thick brass washers) which appear to be unworn.  These are reluctantly replaced by the 5 x figure of eight nylon items supplied in the service kit (see the above picture).   There's probably a good reason for this, but I would be interested to know the thinking behind it.  Also one of the two thin brass discs in the non return valve assembly is replaced with a plastic disc.  It takes a phone call to Burlen to discover which one (its the top one - apparently ?) again - Why

Fitting the five nylon bits around the diaphragm was fiddly but otherwise, re-assembly was fairly straightforward. 
The conversion to solid state was also quite easy and interesting.  An aluminium machined bit (note - the term "bit" is used as a generic term for nondescript items) containing a small magnet is screwed onto the end of the bronze rod in place of the rocker / points assembly. 

Electronic conversion kit fitted.  Aluminium magnet "carrier"
in centre, screwed onto end of bronze rod.

The magnet influences a Hall effect transistor on the PCB which conducts, energising the coil which moves the brass rod and magnet upwards.  Once out of the "influence zone" of the Hall effect, conduction stops, and helped by a big spring, the rod returns to its original position and the whole sequence starts again.  On the pull stroke, fuel is sucked from the tank into a holding chamber and on the return stroke it is sent on it's way to the carburettors.   This is probably an over simplification of the workings, but I think in principle, it's about right.  One thing I have learned, is that the distinct clicking noise is not from the points as I had always imagined, but from the diaphragm centre hitting the body on the pull stroke.

Re-built pump - total cost of parts including electronic conversion
kit and set of new cheese head screws £110.05 plus carriage.
Around the same price of a Facet kit. 

Miscellany - related topics

May 7th, Bank Holiday Monday in the UK saw a few JDC Area 11 members congregate at Croft circuit for a Track Day.  Normally restricted to 88dB maximum (Normal car exhaust level) this was unusually a 105dB day which brought all manner of mad machinery out to play.  My XK140 registered 98dB which I find hard to believe, but was assured that the meter had been calibrated that very morning.

Line up of Jags at Croft.  There was also a full race spec D type
replica, but owner took it home and came back in the 120 OTS

Whilst dry for most of the day, it was bitterly cold.   I did feel somewhat guilty flogging the puddings out of my treasured old 140 fixed head, but any other course would have been pointless.   I also got to ride passenger in a few other exotics, but the highlight was a couple of very quick laps in a C type re-creation (replica would not do this fabulous New Zealand built, tool room copy, justice). I'm never a good passenger but Pilot Geoff Mansfield had me holding on tight with perfect lines and beautifully controlled drifts.  I suppose at his age, he's had an awfully long time to perfect his technique!

Wife Angie's just gone on holiday to Spain, which should mean I'll have a little more to show than a re-built fuel pump in the the next fortnight.

Next Post - Beginning of June