I asked the List about fitting LPG to my car:
“I’ve been looking into carrying out an LPG conversion using a doughnut tank that replaces the spare wheel and putting the spare in the boot. A couple of the LPG conversion companies have said that although that is possible they aren’t sure they can do the engine conversion on the 383 engine with the Carter carburettor. Has anyone any experience of a conversion on these cars.” and “Thanks to those who have replied so far. A common theme is that to convert to LPG with the 383 engine means converting to an unleaded head. Surely it should be possible to run 1 tank of lead replacement petrol to give the necessary lubrication to the upper cylinders and then the equivalent of 2 tank fulls of LPG (at least until the head is converted or not?). The one LPG conversion specialist says he doesn’t think the Carter carburettor can be converted as he can’t find any appropriate adapters. Can a different, up-to-date carburettor be fitted or is he wrong? I am also still keen on the idea of using the doughnut arrangement in the spare wheel location because of the potential of keeping the boot space completely clear and to have a special fuel tank with LPG/petrol compartments, I understand is very expensive.”
I received a number of replies. The following is a summary:
1. You can convert the 440 fairly easily as it is already safe to run the car on unleaded. I have a 1973 111 Interceptor which has been converted. As for the 383 you would have to convert the head to unleaded whilst carrying out the conversion but the carburettor should not cause problems once this is done.
2. I have recently made several long European trips in it (FF) so I have plenty of experience of trouble-free motoring. I have looked at such a conversion in the past and I know someone locally who is both a Jensen expert and does gas conversions. There are two problems both related to the fact that LPG burns at much higher temperatures than petrol. Firstly you will have to suffer the expense of having the heads converted to unleaded fuel with harder valve seats etc. Secondly Jensens do run hot, though the FF is much better than a standard Interceptor, so you will have horrible problems with overheating in traffic – though there are many things you can do to minimise this. Unless you are doing really big mileage in open road conditions then LPG is not really an option – I abandoned the idea, as I only do about 7,000 miles a year.
3. After 18 years with LPG. the Carter you can use ,but better go to a new Edelbrock and a impco LPG installation. This is the only way to keep your performance. Here in Holland with about 15% of the cars running on LPG we think DON’T GO CHEAP.BUT GO FOR THE BEST. WHERE ARE YOU .WE CAN BUY THE DUALTANKS FOR SENSIBLE MONEY OVER HERE
3. Just had my Volvo 940 with 2.3 litre fuel injection engine converted to run on LPG and petrol? Cost £1250 plus vat = total £1468. Car does 24 mpg petrol and 20 mpg gas urban cycle. Petrol costs 69p/ltr and gas 36p/ltr.(4.546ltr=1UKgal).System made by Bedini (Italian) who have installers throughout UK. My gas tank is 70 litre. Doughnut tanks are 50 ltr max, which is only of use for small car. My garage converts Range Rovers and uses 2x 40 litre plus 2x 35 litre = total of 150 ltr capacity. Replaces petrol tank with 2 of the gas tanks and installs 6 gallon petrol tank as reserve. Major problem for Jensen is where do you instal sufficient capacity gas tanks. My system is brilliant (not a legal endorsement).
4. I’ve been running LPG (IMPCO system) in my early Mk3 with the 383 for about 10 years but this has the Holley carb. The 80-litre tank is fitted partly under the rear shelf so that it’s almost touching the seat backs.(Address – IMPCO-BERU Technologies Ltd. “Thie-Ny-Keyll” off Maurys Lane, West Wellow, Romsey, Hampshire S051 6DB Great Britain. Tel – 011-44-1794-323-966 or 011-31-70-399-8304) or Bedini?)
I fitted the lpg system about a year ago now and have been very happy with the results. I have a two tank set up, a 55l donut tank where the spare wheel sits (it fits perfectly and even allows you to bolt the protective cage back on), and a 40l behind the rear seats (against the expansion tank on a MkIII). I can therefore fill the motor with around 81/82l of lpg which is good for 200miles (and combined with a full tank of petrol gives me quite a range. Up front I fitted an Impco300A vaporiser and solenoids. In terms of performance, when putting your foot down hard the acceleration is a little slower (but not much) but there is no difference in cruising speeds etc. I have also fitted a little black box that changes the timing depending on whether you are running lpg or petrol (as lpg likes to be more advance). If I want to drive like a madman I switch to petrol. As it happen at the mo I am not running the lpg as I’m breaking in a new engine (and lpg burns so cleanly it makes running in engines more difficult).