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ANY FRACKING GOOD? Published: 29th Jan 2014 - 0 Comments - Be the first, contribute now!

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Could LPG be the answer to your classic’s rising fuel costs, but without hurting its value?

Never mind the fact that good old George has suspended the ‘fuel escalator’, petrol still costs a lot of money and can have a significant effect on your classic motoring. As most oldies are none too efficient in the miles per gallon stakes, as opposed to smiles per gallon, is converting your classic to Liquid Petroleum Gas worthwhile?

Here’s all you need to know!


Liquid Petroleum Gas (Propane) first came to prominence during WW2. It’s a lot more sophisticated now than when the gas tanks were fitted to a roof rack and today’s installations virtually undetectable. Apart from being significantly cheaper at the pump by almost £1 a litre, it’s also better for the environment as it is a much cleaner fuel than petrol. Also with the advent of ‘Fracking’, there’s more gas than petrol around – apparently.


It works roughly in the same way as petrol insofar that fuel from the LPG tank feeds a vaporiser located in the engine compartment. A simple connector carries this to the carburettor where it enters the inlet manifold in the usual way. A dash mounted safety switch controls the choice of either petrol or gas power.


Typically, from less than £800 to almost £3000 depending upon car and LPG set up. This sounds a lot perhaps, but not when dialled into a long-term car restoration and ownership. LPG won’t improve on your classic’s mpg where the savings come from using the cheaper fuel as much as possible.


LPG used to be criticised as being not quite so efficient as petrol but in today’s octane terms it’s better than five star! Things are improved even more if you use a special ‘gas’ carb although fit this and the car won’t run on normal Modern systems have come a long way and now use fully electronic controls fuel again.


Installation is rather like plumbing in a gas cooker. And today’s kits make it nut and bolt simple although it’s still largely a two day exercise. You must have the completed system checked by an UKLPG-approved agent for insurance purposes.

Indeed, an on-line conversion certificate may prove essential for cover anyway. You sometimes see bargain-priced LPG systems for a few hundred quid claimed for DIY fitting but beware as they can be unreliable and future spare parts perhaps unobtainable although quality has improved enormously over the recent years.

The Rolls-Royce of LPG kits are marketed by Zavoli or AEB.

McLaren Nicholson may be a highly familiar name if you have followed Formula One racing since the 1970s; John Nicholson built some of the best Cosworth DFV engines around. He now markets tailor made LPG installations!


A good quality LPG conversion is usually extremely reliable providing it has an annual service that costs under £100. Every ten years it is recommended that the tank is examined for deterioration and replaced if necessary.

It is important that the ignition system is kept top notch. Some LPG experts argue that expensive ‘gas friendly’ spark plugs such as NGK’s Laserline are used, others argue they aren’t needed, especially for older classic engines.

It’s often overlooked that when setting up an LPG conversion, the ignition timing can be dramatically advanced – as much as 20 per cent according to the engine (due to the fuel’s higher octane value) although this gain is only if a gas carb(s) is fitted as the advancement is too high for normal petrol.

Servicing usually only requires an annual examination, replacing the filters and checking the system. LPG servicing, it has to be admitted, is often overlooked, even by garages who should know better.

As an example, we were told of an Astra fitted with a Vauxhall-fit LPG system. After 90,000 main dealerserviced miles, the car broke down – because the dealer never touched the system.

Why? It never received any training or tooling to do so!


An engine should be started on petrol, which on many installations is done automatically – with carbfed engines you need to empty the


Mark Wain used to be a well known classic car restorer (hence the WCR title Wain’s Classic Rebuilds (01603 879879) but got fed up with the sheer cost of petrol and repairing customers’ vehicles because they left petrol in their classic’s tank over the winter which had gone ‘off’. He studied LPG conversions and has become so proficient and well known that converting vehicles of all types and ages is now his mainstay business.

To say he is a convert is an understatement. All his vehicles run on LPG (East Anglia is said to have the highest concentration of LPG filling stations in the UK), including a working tractor, run from a calor gas bottle! When we visited Mark, he was working on a Ford development car. He says that even little used classics are worth converting as the £1 or so gulf in LPG and unleaded prices makes it viable, plus the higher octane gives better performance. He has converted Morris Minors and MGs but admits it’s the ‘big stuff’ where the appeal really lies and recently LPG-ed a Rover-powered Stag.

Typically, a fitted system for an MGB or Mk2 Jaguar, using the popular Italian AEB or Zavoli kits costs around £900 – bigger engines cost a bit more. And the more you make use of the cheaper fuel, the quicker you’ll recuperate your outlay.

Best of all, says Mark, is that LPG can’t go ‘off’ and so you can leave it in the tank all year round carbs by turning it over. But it’s not vital, witness the rise of gas-only conversions Periodical running on unleaded is advised to help lubricate the valves and keep the system clean or failing this there’s a £45 kit that provides a special lubricant to lube the valves at the press of a switch. It’s so effective that it can also be fitted to petrol-only cars to protect unleaded valve seats as well, says LPG expert WCR LPG of Norfolk, who provided much of the advice contained in this feature.

If there is a point to watch then it’s hot running engines. This is not a good situation for classic engines at the best of times, especially if the valve seats have not been converted. Certain LPG experts recommend special ‘gas-friendly’ spark plugs to improve efficiency but, WCR thinks that they are largely not needed (they are very expensive, too-ed).

A certificate of conformity (installation quality) is important. If a car or conversion lacks this it then you may find it very hard to find an insurer. Check with your insurer to let them know of the conversion.

Failing to do so may invalidate your cover. In the case of the MoT, the system is checked for leaks and the wiring condition – emissions too if the engine is running on gas at the time of the test.

Filling up with LPG is pretty simple but takes longer to do than petrol so you can’t splash and dash.

The pump’s filler has to be locked in position and a button on the pump is used to supply the fuel. A small amount of LPG is expelled as you release the filler but it’s nothing to worry about.


Sadly, other benefits are being taken away from LPG vehicles such as congestion charge exemption; Boris is removing the London one for 2014 and not all conversions were applicable anyway. If you are having a kit fitted, ensure it and the installation complies with BSEN 12805:2002 and UKLPG. A proper installation should come with an (on-line) UKLPG registration for insurance purposes and 12 month warranty.


It’s the $64,000 question, isn’t it? If you are a stickler for originality then, yes it could well devalue your classic. But there’s no ill feeling towards a gas conversion say car clubs, sometimes it’s a sales advantage. So why not go ahead and have some fracking fun!

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