Now I have TWO Discos! Help needed (with swapping LPG, components etc)

**Milhouse** · 6th June 2010, 01:36 PM

Hi,

Well I had a rush of blood and just bought another Disco - this one is a 1997 3.9V8S (green) - to replace the old 1992 3 door 3.5V8 (blue).

What sold me was the massive increase in pull from the new(er) one from the tired old girl (even when she was running well - which she isn't now...).

Anyway prior to off loading the old Disco I probably want to swap a few things over - bull bar etc not too difficult but its the LPG that I'm interested in a bit of advice on. Will there be any problems swapping the system from a 3.5 to a 3.9, should I get a totally new system (obviously a number of the existing gas components will require replacement), the tank is in the boot and has about 9 years left on it. Preliminary phonecalls to fitters in Sydney seem to suggest the cost of swapping will come in on or below the $1750 rebate mark - can anyone recommend a good place in Eastish Sydney?

Also want to swap the dual battery system I fitted to the old one into the new one and as this will require movement of the coil and p/s reservoir will probably get this done when the LPG is fitted.

Another point is the old Disco was fitted with a Foam Unifilter which might make it a bit less of a squeeze to fit the 2nd battery) any thoughts on whether or not to keep this - I'm guessing it would be fine for the slightly larger engine but I've heard mixed reports on whether they are actually an improvement on OEM.

Also will be giving the new one a service - apart from the obvious oil change etc anything in particular that I should definately do/look for?

Anyway, thanks in advance,

Cheers

Steve

**Pedro_The_Swift** · 6th June 2010, 02:37 PM

Read our Filter test in The Good Oil

oh,, and swap the mags,,,

**bee utey** · 6th June 2010, 03:24 PM

Remarkably your new 3.9 will feel much like the old 3.5 if you reinstall this lpg system. Yes, it will work but there is stuff that's heaps better on performance and economy. The tank will be fine so long as it suits your usage of the boot space. There is a dual filler arrangement available meaning you won't need a filler in the lower side panel too. And the lpg rebate goes down to $1500 on 1 July 2010. The best air cleaner to end up with is the cylinder type fitted to the late 3.5 and early 3.9EFI. Then you can make room for the second battery when you juggle everything in.

**Milhouse** · 7th June 2010, 08:55 AM

Originally Posted by Pedro_The_Swift

Read our Filter test in The Good Oil

oh,, and swap the mags,,,

Cheers for the link - looks like paper is the way to go for filters - and dirty at that!

Yes I will be swapping the mags over - I have another set of steelies anyway - on that point anybody know where I can get a cheap wheel nut suitable for the mags - I'm missing one and previously I had to pay $20 for a new one

**Milhouse** · 7th June 2010, 08:57 AM

Originally Posted by bee utey

Remarkably your new 3.9 will feel much like the old 3.5 if you reinstall this lpg system. Yes, it will work but there is stuff that's heaps better on performance and economy. The tank will be fine so long as it suits your usage of the boot space. There is a dual filler arrangement available meaning you won't need a filler in the lower side panel too. And the lpg rebate goes down to $1500 on 1 July 2010. The best air cleaner to end up with is the cylinder type fitted to the late 3.5 and early 3.9EFI. Then you can make room for the second battery when you juggle everything in.

Cheers for the reply,

Roughly how much would I be up for to fit one of the new better style systems? And what are they called - so I know what to talk about to the fitters...

If fitting a different style system would there be any point in pulling the tank from the old disco?

**bee utey** · 7th June 2010, 11:54 AM

Originally Posted by Milhouse

Cheers for the reply,

Roughly how much would I be up for to fit one of the new better style systems? And what are they called - so I know what to talk about to the fitters...

If fitting a different style system would there be any point in pulling the tank from the old disco?

The better performing systems cost roughly the same as the Impco stuff. There is no specific brand/type that is absolutely the best, but generically you want a "ring" type mixer system. It's success lies in getting the right size mixer ring and converter combination, then also the right petrol assisted start adjustment. PM me if you get no sense out of your local gas installers, I may be able to help with specific part numbers.

If you are dismantling the old Disco use the tank by all means. If you are selling it afterwards leave the tank in. Makes it worth more.

**Crackerjack** · 10th June 2010, 09:29 PM

Correct me I'm wrong, but won't you need to upgrade the LPG system as the 3.9 has different electronics to the 3.5 engine

**bee utey** · 10th June 2010, 09:41 PM

Originally Posted by Crackerjack

Correct me I'm wrong, but won't you need to upgrade the LPG system as the 3.9 has different electronics to the 3.5 engine

The only real difference is the placement of the mixer on the intake. A flapper AFM usually has a mixer ring on its inlet, the hotwire has it on the throttle body. The electrics are much the same, you cut two injector wires in the main harness to disconnect the injectors and bob's your uncle. I usually cut the power wires and join them so only one relay is needed, you just need to repower the hotwire AFM as it runs off the injector feed.

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