Carburettors

[Forumadmin]

In an attempt to return the DelLorto carbs borrowed from John Blankley I have been searching my stock of about 30 'spares' most of which have worn throttle butterfly shafts.
Does anyone have experience of the relative performance of the 30VIG and 30 VM? I realise that the 30VM replaced the 30VIG but was this because of fuel economy, performance or price?

At an autojumble I bought two 'new' 30VIG-11 carbs that were not a pair being Contract Numbers 1461 and 1460. These are close to the 30VIG-5 fiited to the early Jups having an acceleration pump.
I also have the two 30VIG-5 originally fitted to the SA Jup and now replaced by DelLorto. These are Contract Number S1194-12 and 1245, so again not a pair.

I have cleaned up the carbs in boiling vinegar (on our new cooker!). I decided, perhaps foolishly, to exchange the throttle and choke actuator levers and the link and lever for the accelerator pump. The choke lever is proving a problem as the offside(UK) carb ( the C1245) has an arm braised on after assembly. This will require cables to be used rather than the original 'U' arm that goes between the two carbs. The DelLortos that are fitted have cables. The choke mechanisms are much simpler on the -11 and do not have the two cams that are on the -5.

Assuming I get a working set of bodies I will then turn my attention to the jets. My next post will start a discussion on this!

[Forumadmin]

I have done an inventory of the carbs in my posession.
12 off C1161m
3 off C1316
2 off C1074
3 off C1334
5 off C1343

These went with the following float chambers with jets
6 off 26 45 90 50
1 0ff 25 45 90 55
1 0ff 25 45 90 50
1 off 25 45 120 50
1 off 25 45 120 65
1 off 26 45 120 65
Also have a five chambers which do not have jets or jets are not identified.

VMEspareslist.gif

Illustration No + Description
1 Choke flap screw x2
24 Screw fixing emulsion block (short) x4
2 Choke flap
25 Body
3 Screw fixing bowl to body x2
26 Throttle disc
4 Gasket (bowl to body)
27 Throttle disc screw x2
5 Float
28 Throttle lever & stop
6 Drive screw fixing gasket x4
29 Spring washer
7 Slow running jet
30 Nut for throttle spindle
8 Screw over capacity well
31 Floating rod & interconnection rod
9 Washer for needle valve
32 Throttle spindle
10 Needle valve
33 Spring for throttle stop screw
11 Carburettor bowl
34 Throttle stop screw
12 Plug for main jet
35 Screw for fixing choke tube
13 Aluminium washer for 12
36 Shakeproof washer for 35
14 Main jet
37 Air regulating screw
15 Washer for 14
38 Spring for 37
16 Plug for compensating jet
39 Spring for choke lever
17 Aluminium washer for 16
40 Choke lever
18 Compensating jet
41 Circlip for choke lever
19 Washer for 18
42 Choke flap spindle
20 Gasket for emulsion block
43 Choke spring (automatic)
21 Emulsion block
44 Screw for interconnection swivel
22 Washer for 23
45 screw for choke swivel
23 Screw fixing emulsion block (long)
46 Choke tube


I also found the other C1245 body and float chamber with jets 55 50 90 105 to match with the other original carb ? 45 55 and 105
The other VIg chamber jets -- 50 and 90, 55 50 90 105 and the Bedford CA chamber ? 56 22 70 and 92. (Note these last two have an extra jet)
In the 30VIG diagram below 40 is the pump jet (inside the emulsion block), 41 the idle jet, 39 the main jet and 38 the compensating jet.

VIGspareslist.gif

1 Choke flap
36 Fibre washer for compensating jet
2 Choke tube
37 Pump non-return valve
3 Air regulating screw
38 Compensating jet
4 Spring for 3
39 Main jet
5 Choke spring (automatic)
40 Pump jet
6 Spring carrier
41 Slow running jet
7 Split pin
42 Ball valve for pump circuit
8 Choke tube fixing screw
43 Pump piston spring
9 Bearing plate screw x2
44 Pump piston
10 Bearing plate for pump control
45 Pump piston stop screw
11 Pump control lever
46 Float
12 Pump control link
47 Throttle disc screw x2
13 Washer for 12
48 Throttle spindle
14 Split pin for 12
49 Needle valve
15 Lever & interconnection link
50 Needle valve washer
16 Washer for throttle spindle
51 Olive for auto ignition connection
17 Throttle lever
52 Plug for 51
18 Lockwasher for 16
53 Top bowl gasket
19 Throttle spindle nut
54 Drive screw for 53 x4
20 Economy diaphragm gasket x2
55 Plug for petrol connection
21 Economy diaphragm
56 Olive for 55
22 Economy diaphragm spring
57 Screw, bowl to body(plain type)
23 Economy valve cover
58 Screw, bowl to body(jet key type)
24 Screw for 23 x3
59 Pump rod
25 Throttle stop screw
60 Pump rod spring
26 Spring for 25
61 Washer for 60
27 Body
62 Washer for pump rod pivot
28 Throttle
63 Split pin
29 Emulsion block screw (short) x4
64 Choke flap screw x2
30 Emulsion block screw (long)
65 Screw for interconnection swivel
31 Washer for lower block screws x3
66 Choke spindle
32 Emulsion block
67 Choke lever bearing
33 Carburettor bowl/emulsiongasket
68 Screw forcontrol wire swivel
34 Carburettor bowl
69 Choke lever
35 Fibre washer for main jet
70 Choke spring

[Keith Andrews]

One has to keep in mind these carbs where mainly for British pool fuels between 1938 and 1954 (?)
Since then the composition, octane and speific gravaty of fuel has changed considerably, including no lead, lead added and again lead removed.
Our moderbn fuels have lower SG, higher octanes, which means althu they have more BTU per mass they have less BTU per volume....which means larger jetting and more advance.

One question thu, anyone know the diam of the reemer to use for replacing worn throttle bushes?

[Forumadmin]

So how do we theoretically predict, or guess what the jets should now be?
The first step should be to understand the workings of the Zenith carb to see what governs flow of petrol. Firstly we should concentrate on the 60mph, constant speed, low throttle setting as that is what the car does most of the time on motorways. Keith A., by your premise, should all the jets be widened a notch? and how big should that notch be? Zenith go up in steps of 5 but some jets may be hard to find!
So this is the original ste of sizes.
....................................Jupiter.........Javelin
...................................30VIG-5 30VM 30VM-4 30VM-5
Zenith Contract Sheet Number C1245 C1316
Carburettors,.................... Jet Sizes:
Main ................................105 120......90........90
Compensating......................60 65.........55........50
Pump Jet............................90 –
Progression.........................– 120
Leak.................................70 –
Vent..................................– 2.5
Slow Running.......................45 45........50..........45
Choke...............................26 27..........23.........25

On the 30VIG-5 Should we take the main up to 120?

Perhaps looking at other applications of the 30VIG ZENITH might help? The Hillman Minx being the last fitted with the carb in 1960.

AS FITTED TO

Austin A40 Somerset 1952-55

Austin A40 Cambridge (B Series engine) 1954-55

Bedford 5/6Cwt, 10HP; H. C. Model 1945-46

Bedford 10/12Cwt, 12HP; J.C. Model, 1946-48

Bedford 10/12Cwt, 12HP, P.C. Model, 1948-52

Bedford CA Van 10/12Cwt, to engine No. 66975, 1952-56

Bedford A2 Utility, A3 Truck, to engine No. 99999, 53-57

Bedford K & M Models, 1946-52

Bedford O Models, 1946-50

Ford Consul Mk I, 1951-56

Ford Zephyr Mk I, 1951-56

Hillman Minx Series IIIA, Manual & Auto, 1960

Jowett Jupiter Mk. I, 1951-56

Morris MF3 Utility, 1958-60

Vauxhall 10HP, 1945-46

Vauxhall 10 & 12HP. 1946-47

Vauxhall Wyvern, 12HP, 1948-51

Vauxhall Wyvern, 16HP. To engine No. 102999, 1951-56

Vauxhall 14HP. 6 Cyl. 1946-48

Vauxhall Velox, LIP, LBP, 18HP. 1949-51

Vauxhall EIP, to engine No. 242999, 1951-56

This was listed at another site
Jowett Javelin 13 h.p. (1.5 litre) 1947-48 Carb Type Two 30 VM-4 : c/s 1084

[Keith Andrews]

Ideally one should be tuning with something like the innovate lm 1 or 2
But its all a total waste of time if the throttle bushes are worn....or even trying to compensate for any wear...unless it is a 4 barrel and the sec butterflys can be closed.
If u compensate for cruise circuits, it will screw the power and idle circuits and visa versa.
I think the 1st thing you would be trying to get is around 11:1 WOT, then start to aim for mid 14:1 at cruise/idle.

And keep in mind with the higher octanes assuming the DCR remains the same a little bit more advance /rate of advance will be required.
One can not just adjust mixtures without adjusting the advance to suit....
A simple example of this is setting up idles..both intial and mixtures are adjusted together...the same applies to the other carb circuits.

One can mess around with carb makes dual carb set ups in a hit and miss fashon...at the end of the day one needs the carb to be able to delever the cfm of air AND the volume of fuel energy + approx 15% for the required HP intending to devalope at max power....
EG a given 465 cfm carb can deliver around 260 hp of air/fuel mixture but put it onb a say 350 ci engine and it will start to lean out around 4500 rpms...not detonate but will eventually melt pistons, burn valves etc. when one gets much above these rpms....yet the max power range could be say 6000 rpms.
So if yopu have an engine 350ci devalopes 260 hp at 6000 rpms u will need around a 600 or 650 cfm carb
If it devalopes 600 hp at 6000 rpms you will need around a 850 cfm carb...to deliver enough fuel (BTU) AND air for a 11:1 ratio

So how do we theoretically predict, or guess what the jets should now be?

So its not a matter of choosing jets...1st one must choose a carb that will deliver enough oxygen for the hp intending to devalope at a given peak rpms.....THEN jet to suit to establish that 11:1 ratio....then sort the cruise idle circuits.

[Srenner]

Mr. Andrews is quite right about the jetting changes needed to accommodate modern fuel. Over the years of building the same spec Frogeye Sprite 948cc motor, the jetting has moved to the richer side. A friend builds Porsche 356 race motors and has noticed the same thing. It's even worse for street motors due to the mandate on changing the formulation of the fuels for winter and summer. In addition, somehow corn ethanol is now the "hot" additive, wreaking further havoc. Not hard for an ECU, but hell on old time carbs.

We have the "advantage" of running these race motors on engine or chassis dynos to get the jetting right. VERY expensive, but much less so than burning a piston.

And I agree, the timing and the mixture go hand in hand. And the carbs need to be in good condition.

Here's what we are trying now for street motors.

My pal just bought the Innovate system that one sticks in the tailpipe and, with a couple timing light-like connections, one can drive the car around the block recording all the data needed to re-jet the car. It has a readout of the stoichiometic ratio, so if you watch while you drive, you have a great way to observe it all in real time. Download to the laptop or PC and there are multiple things to examine, including timing, advance and idle data.

I have to admit this is pretty economically uninviting for the average enthusiast.

I will be going through my books, as I have one specific to Zenith carbs. Will see if there is any thing applicable in there.

[Keith Andrews]

It's even worse for street motors due to the mandate on changing the formulation of the fuels for winter and summer. In addition, somehow corn ethanol is now the "hot" additive, wreaking further havoc. Not hard for an ECU, but hell on old time carbs

This whole issue goes back to dropping of lead and replacing with lower SG fuel fractions....but the BIG issue is going from 1950s fuels to modern fuels which is a huge change in BTU per KG and octanes, speed of burn acros the chamber.
I have been playing with this sort of thing for near on 30 yrs now... mainly on street and street/track engines.

We have the "advantage" of running these race motors on engine or chassis dynos to get the jetting right. VERY expensive, but much less so than burning a piston.

With all due respect, I have very little time for those who tune up cars on dynos...they are a rip off.
Generally they turn a dizzy a few degrees and maybe swap a couple jets...yes the improve things....and the customer thinks thew sun shines out the guys #$%^*....not ever knowing hes just done a couple basics, which with a little knowledge could be done without spending a fortune.....and theres a heap more potentual to be tapped into...this is espec the case with a street engine...Most of these guys estimate the weight of the car, have no idea of wind coeffient (if known) just set for sea level, asuming thats where the customer operates/lives, and dont bother with ambiant air temps etc.

My pal just bought the Innovate system that one sticks in the tailpipe

Do u have the LM1 or LM 2 the LM 2 a lot of ppl are having issues with incorrect readings with faulty leads.
The best way is not tail pipe, blow a hole in the exhaust pipe and weld a plug in so the Bosh wide band sensor screws in.
When finished connect an after market gauge, or mount the inovate unit or remove sensor and put a blank in.
It is worth the forto do this
Make sure it is on the upper side of the exaust pipe.
NEVER run a O2 sensor not connected to a gauge or load, and do not run on a anolog volt meter..digital onlt.
One can buy led and dial gauges instread of the more expensive inovate units...these indicate ratios/lamba they are not suitablefor tuning because they do not 'zero' the sensor.

I have to admit this is pretty economically uninviting for the average enthusiast.

I disagree, would have agreed maybe 3 or 4 yrs ago, not now.
I of these units is about the same price as a dyno secssion ...
Using one on a bit of open high way, or private land, one automatically is tuning for car weight, wind co efficient etc.
Think about it...indy, F1 do they just dyno and race? no they dyno to get in the ball park THEN monitor and race Technology is here and affordable to joe public to do the same on our old cars.

Has anyone air flowed these carbs at 1.5".. knowing that and having that data would go a very long way from the old hit and miss method of the last 70 odd yrs.

[Forumadmin]

Good to get some discussion; but let me set some constraints. The subject is the 30VM Zenith with no intention of looking at another carb. That way any results will benefit all Jowett Jup and Jav owners.
We should assume the carbs have been overhauled; but I would like to know what that entails besides cleaning everywhere and fitting new throttle spindle and butterfly if required. Also rebushing (or tinning the spindle as suggested by Bill Maris), if required.

We are not going for top end power; but an economical balance for a road car, as the price of juice is rising every minute. We do need to know how the 30VM works in detail so as to know the inter-relationship of all the variables. Has anybody a good explanation? We might even have a go at a lean burn mixture for those wanting to do an economy drive.

We should assume it is a 1500cc engine with max revs of 4500rpm. Where do all the jets in a 30VM come into play?

I am happy to road test Jenny's Javelin with any suggestions,if necessary I will take it on the rolling road.

We may be constrained by availability of jet sizes; so doing some theory first would save time, effort and cost!

So what is the difference between the 1950 fuel and the 2011 fuel, we need values or percentage change.

In my research found this useful list of carbs used by Jowett.

[Keith Andrews]

Give mev a holley carb, I can pretty well tell u if u need a double pumper /vac sec cfm jetting and be close off the top of my head...
All carbs work the same BASIC way
1/ there is an idlle circuit that 'bleeds' mettered air or fuel past the buttflyies..the mixture screws
2/The tranistion, this as the butterflies open, tranistioning past the idle slots
3/ Cruise...this is generally the main jets
4/Power this is a boost from a pump and in the holley a power valve rated to the vac of the engine

Each think of as a separate carb and tuned appropately...ie idle curcuit a little lean, power rich around 11:1, cruise little lean.

We are not going for top end power; but an economical balance for a road car,

Economy = efficient use of the fuel
Power = efficient use of fuel
When dealing with a 'street car' rather than a specialst track car, both of these are the same.

So what is the difference between the 1950 fuel and the 2011 fuel, we need values or percentage change.

I have covered this several times in old posts..basically the british pool fuel was (with out looking up again) somewhere between 62 and 72 octane, usually at the low end, hence why these old engines ran a basic 'square' profile cam, nil or very little overlap and duration, and very low compressions to suit.
There is an old post where I discuss, reducing octane to suit, which resulted in very marked power and economy increases.

At the end of the day, an efficient engine (as these where in their day) is primarily a balance of DCR, octane, timing, and carburation to suit.
Unless one wants to blend their own low octane fuel, a compromise has to be made with hi octane (91) low compression, then adjust (advance) timing and carburation to suit.
OR do what Hot Rodders are moving into these days with dramatic resultsa on old carbed engines...FI

We should assume it is a 1500cc engine with max revs of 4500rpm. Where do all the jets in a 30VM come into play?
I am happy to road test Jenny's Javelin with any suggestions,if necessary I will take it on the rolling road.
We may be constrained by availability of jet sizes; so doing some theory first would save time, effort and cost!

If it is running ok..that is will be the starting point as I mentioned in the previous post...From there map the O2, under load, accel , idle, cruise.....alter one at a time, to improve, adjust the timing to improve , map again, adjust timing.
If doing for a living one will do it in a day, if for a hobby, head out on a trip, change re check, then something the next day or trip..

[Forumadmin]

All carbs work the same BASIC way

The 30VM has six variable elements, (main, compensating, progression, vent, slow, choke) so what is the working relationship between all of these?
Can we explain the purpose of each ?

both of these are the same.

Not really, it is normal for performance cars to have a greater amount of fuel than a leaner burn car tuned for economy, especially in a carburettor engine. The dynamics of street driving and rally driving do not lend themselves to stoichiometric theory! I am intrigued to know why the more modern 30VIg was dropped by Jowett in favour of the older 30VM. I suspect cost and complexity. Was the 30VIg better at acceleration? The Jowett also has a problem with interference between both banks of cylinders which might upset any theory based on a single carb.

I have covered this several times in old posts

So if we assume that the combustion chamber flow and compression ratio and other possible aspects have not been modified from original Jowett design, should we change the jets in the carb? Answer is yes I suspect! So what do we change them to? Is at as simple as octane changes by 50% (60 to 90) so jet size goes up 50% or should it go down by 50%?

Why is the 30VM in the Javelin (90,50,110,2.6,45,?) jetted so differently to the Jupiter (120,65,120,2.5,45,27) when they are the same engine?

In the diagram below for the 30VM which parts list numbers are the progression and the vent?
(main = 14, compensating=18, progression=?, vent=?, slow=7, choke=46)

[Chris Spencer]

You may find the following specialist supplier of interest : www.carburettorspecialist.com - I used them when rebuilding the SU carbs on my Rover - they keep a vast amount of oddball stock

[Keith Andrews]

The 30VM has six variable elements, (main, compensating, progression, vent, slow, choke) so what is the working relationship between all of these?
Can we explain the purpose of each ?

like I said I know holley ..Im not familar with the workings of other carbs just as no doubt you are not familar with holley, but each of the eliments you mention still work and do what I mentioned above..mosyt prob the diffrence is terminlogy ie progresion transition.

Not really, it is normal for performance cars to have a greater amount of fuel than a leaner burn car tuned for economy, especially in a carburettor engine.

That is what I said...

Code: Select all

Economy = efficient use of the fuel
Power = efficient use of fuel
[b]When dealing with a 'street car' rather than a specialst track car,[/b] both of these are the same.

So if we assume that the combustion chamber flow and compression ratio and other possible aspects have not been modified from original Jowett design, should we change the jets in the carb? Answer is yes I suspect! So what do we change them to? Is at as simple as octane changes by 50% (60 to 90) so jet size goes up 50% or should it go down by 50%?[/quote]

This is where we use modern technoloy as suggested above with intruments like the Inovate LM 1 and LM2
A simple thing like skimming a head, head gasket thickness, a re bore all change CR and DCR...If one has a engine tuned in right, then does a basic re bore everything changes...in that engine, one cant expect to run the same timing curve or jetting....

Why is the 30VM in the Javelin (90,50,110,2.6,45,?) jetted so differently to the Jupiter (120,65,120,2.5,45,27) when they are the same engine?

Engine weight, final gear ratios, air co rfficent..these all cause different engine vac charactoristics at different speeds and loads...which also requires changes in timing...which is why I mention these re dyno tuning and road tuning in post above.
Even 2 identical engines are very unlikely to have the same tuning ...one can and manufactures do run production that do have all the same tuning charactoristics, but as we all know , in most cases , including modern EFI there is ample room for significant improvements to aftermarket tune (jet/timing) to improve both power and econonmy.
Generraly car manfactures and carb applications 'out of the box' are still to rich...this stops come backs/legal proceedings if are too lean and burn pistons etc...ie when one buys a holley there are 100s of combos one picks for ones application, auto manual , gear ratio , engine size, cam profiles etc etc..but once on the car generally one can drop 2 often 3 jet sizes, and increase the rate of advance.

The old hit and miss went out 30yrs + ago with hot rodders, track pit crews with the advent of chassis and engine dynos , CO HC O2 meters... the latter 2 I have in my 'tool box', chassis dyno I have had access to...I have spent 30yrs messing around with these...Both hi CR low CR hi octane, low octane fuels, carburation, machining dizzies , re curving, and designing cam profiles.
If one wants to get real serious in tuning these old engines, yep one can also thow on air flow meters, knock sensors , O2 sensors, water and oil temp sensors, hok them all up to an anyliser like a Inovate, hook into a lap top on the passengers seat a get 3 dimensional mapping, same as with modern ECU chip programing on modern cars...the diff being instead of changing the chip program that changes fuel discharge timing etc, we directly change jets , timing etc.

And believe it or not, these old carbs are far more efficient than what people these days commonly believe, when compared to EFI.....for street application,...The down side of carbs is they tend to work most efficently in a narrower rpm band width than FI....but when talking normal street use, 500 rpms to 2500/3000 rpms , that is a reasonable narrow rpm range for a carb and each of its circuits.

[John Dolphin]

The 30VM has six variable elements, (main, compensating, progression, vent, slow, choke) so what is the working relationship between all of these?
Can we explain the purpose of each ?

Choke - The choke size defines the diameter of the throat of the venturi. For a given airflow a smaller choke would result in a greater depression at the throat of the venturi. Greater depression results in greater fuel flow for a given jet size. The downside of decreasing the choke size is that it restricts airflow into the engine at wide open throttle. According to the Jan 1952 Javelin Technical Data document the Javelin used 23mm chokes. As Keith mentions the Jupiter used 26mm chokes but then the Jupiter was rated at 62.5 hp at 4500rpm and the Javelin at 52.5hp at 4500rpm. The increase in power for the Jupiter engine was probably achieved by a combination of compression ratio increase, spark timing changes and choke size increase. Incidentally the techical data for the Javelin and Jupiter indicate that there were other differences between the carbs used on each of the cars.

Main & Compensating Jets - The main and compensating jets work together to regulate the fuel flow as the depression at the throat of the venturi varies (as engine speed & throttle opening vary). In simple carburettors using only main jets the air fuel ratio tends to be too lean at low engine speeds and too rich at high engine speeds. The compensating jet is used to richen the air fuel ratio at low engine speeds and to lean it out at high engine speeds.

Slow Running Jet - At very low engine speed, with almost closed throttle, the depression downstream of the throttle is usually greater than that at the throat of the venturi. Therefore for stable slow running the fuel is introduced just slightly downstream of the throttle. This fuel flow is regulated by the slow running jet.

Progression Jet - The progression jet is used to help smooth the transition between running on the slow running circuit to running on the main & compensating circuit.

Vent - I'm not too sure what this refers to on the Zenith Carb. It could well be a vent hole on the top of the float chamber to ensure that the chamber is always at atmospheric pressure.

From what I have read regarding the tuning of carburettors I understand that it was usual to run a lean air fuel ratio at part throttle and to run a rich air fuel ratio at wide open throttle. This was simply because best economy is achieved slightly lean of the stoichometric air fuel ratio and best torque is achieved slightly rich of stoic.

Hope these notes help and I look forward to further debate.

John Dolphin
E3SA 887

[Forumadmin]

Ordered some new parts for the carbs. midday and they were on the doorstep within 5 hours.
Not only that, http://gowerandlee.co.uk/ were wonderfully helpful. I will have a go at refurbishing them myself; but if that does not work they do that as well.
Part num desc ...........price ....... qty
30VM
14057 throttle spindle... 9.38.... 2
7340 throttle butterfly... 8.72....... 2
GP 6 gasket pack........ 3........ 2
B19052 1.5mm needle valve 7....... 2
7mm bush............... 2...... 4

30VIG
accelerator pump check... 5.3...... 2
14103 throttle spindle... 5.3...... 2
7340 throttle butterfly.... 8.72...... 2
GP 7 gasket pack...... 3......... 2
06605/105 ............. 7.14...... 2
06620/60............... 6.06.... 2
7mm bush.............. 2......... 4

[Forumadmin]

I have commented elsewhere on progress rebuilding the 30VIG carbs which was all going well until the final task of connecting up the petrol pipes when I discovered a crack in the casting that takes the filter banjo. So if any body has any ideas on how to weld a carb casting please speak now! I have taken off the offending offside carb, but the three spare 30VIgs I have are all nearside carbs, and would need the choke assemblies swapped.
I also failed to identify the thread (and I do not have a tap) for the fitting. Is it 20tpi 1/2inch BSP? I also noticed I had a brass filter with a different (coarser) thread which could have done untold damage if used!
When everyone is back from hols I will phone up Carb Exchange in Leighton Buzzard to see if they have any ideas. I suspect they will say 'scrap the body'!