Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

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Morat
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Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#1 Post by Morat » Thu Oct 01, 2015 3:22 pm

Good people!
I'm looking very seriously at a Grand Cherokee (as per title) and I'm wondering what the collective wisdom is on converting one to LPG. They seem an obvious target for gas and many seem to have been done, but are there any pitfalls? Does anyone know off the top of their head what size tank would fit in the wheel well? I suspect that range would be an issue with such a thirsty beast.
Would £1500 be a reasonable budget for converting one?
thank you all, again.
Morat

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#2 Post by LPGC » Fri Oct 02, 2015 3:17 am

I've converted literally dozens of these (and other models - 4.0, 4.7, 5.7, 6.1). Going back a few years I almost got sick of working on them as I converted maybe 10 in a row! All convert well provided you know what you're doing,..

If it's a wheel well model, a 720 x 79 litre full toroidal tank will fit and keep the boot floor flat (provided you remove the 2nd skin from the wheel well lid and batter the well bulge down a bit, which first involves lowering the petrol tank). A more capacious taller tank would fit but involve raising the boot floor, so 79L is more popular.Bit difficult to fit though - Petrol tank is under the wheel well, metal guard surrounds either side of the exterior of the well, valve can be fitted at between 10 and 11 O'clock or near 5 O'clock (bearing guards in mind). A fair bit of fabrication is needed to secure tank properly.

Engine is pretty much a doddle but has unusual electrical spec petrol injectors and petrol ECU picks fault if you wire ign live and/or rpm pickup wires somewhere it takes exception to.

You should get an excellent job done on your budget, provided you don't go to the wrong installer! Definitely do not fit Prins to this model..as I and other pros have noted Prins seems to cause VSR issues on this model.

I don't know where you are or would say phone me regards a conversion....

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#3 Post by Sir Henry » Fri Oct 02, 2015 9:25 am

I had mine done in 2006/7 in Sheffield. That fitter has since given up on doing conversions due to the number of dodgy fly-by-night one day fitters that came on the scene pre 2010. However he fitted a large under body gas tank (100 litres or more) alongside a much smaller petrol tank as well as a new skid plate to protect both. Back then the overall cost was about double the current average, but prices were higher, on the whole, back then.
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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#4 Post by LPGC » Fri Oct 02, 2015 1:08 pm

The earlier Jeep GC's had the spare wheel stood up at one side in the boot, on those models the options were to fit a stand up toroidal tank in the luggage area, a cylinder tank in the luggage area (like mine) or the replacement petrol tank and gas tank both underslung. On later models with the spare wheel well under a flap in the boot (like the one discussed here) we usually fit a spare wheel tank in the well. Later models still have the spare underneath, on which we usually fit an external spare wheel tank underslung.

Simon
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Morat
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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#5 Post by Morat » Fri Oct 02, 2015 1:33 pm

Simon thanks for the info - much appreciated.
I'm about 20 miles beyond York from you, so not exactly local but within range.
If we end up buying the beast you'll be on a shortlist of two :)

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#6 Post by Sir Henry » Fri Oct 02, 2015 2:06 pm

If you go to Simon please take note of this google earth view. https://www.google.co.uk/maps/@53.59963 ... a=!3m1!1e3

His yard is in the middle of the picture rather the middle of that side road. Access is down the track to the North directly off Mill Lane and access is better when approaching from that direction.
If I can't break it nobody can. Failures to date: Nil! ;)

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#7 Post by Morat » Fri Oct 02, 2015 7:32 pm

So I get to do a little offroading too :)
thanks for the tip!

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#8 Post by robbie1003 » Fri Oct 02, 2015 9:17 pm

i had the 4.7 v8 limited fitted with remano lpg system on and it was fab, only problem we had was the tank in spare wheel well of 79l isnot big enough to be everyday practical, we were filling it twice and three times a week which is a pain.

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#9 Post by Sir Henry » Fri Oct 02, 2015 11:04 pm

Mine was the 5 point summat. Big bastard it was and required a refill at home, in Hull (twice) and back at home again on any trips to Belgium via Hull. Only the Shadow used (uses) more fuel!
If I can't break it nobody can. Failures to date: Nil! ;)

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#10 Post by Morat » Tue Nov 03, 2015 7:11 pm

Damn it, just seen a tempting 4.7 overland in Bradford - but it has Prins on it already :(
Thanks for the heads up though! I don't fancy replacing two cylinder heads.
Linky
Is there any way to test for VSR without taking the heads off?

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#11 Post by LPGC » Thu Nov 05, 2015 1:33 pm

Morat wrote: Is there any way to test for VSR without taking the heads off?
Compression check / use a borescope through spark plug holes to view valves from inside the cylinders.

If this car is what you want and compression etc are ok (seeming OK - smooth idle when cold and hot... unless you fancy taking a borescope to sellers!) I wouldn't be too worried about it having Prins. I reckon most issues with Prins on these have been caused by the Prins not being calibrated well - which could be easily sorted.

If still worried about Prins, remove the front end, sell it and have a different system fitted - You'd probably only have to put a £few hundred in after selling the existing front end for a pro to do the work - I'd do it.

Simon
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Morat
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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#12 Post by Morat » Thu Nov 05, 2015 8:32 pm

Gone now. Ideally I'd like a non-converted one because they inevitably have lower mileage :)
Thanks again, though - handy hints!

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#13 Post by Tubbs » Fri Nov 06, 2015 6:53 pm

Shame ! Least you know to look for a flashlube now ?

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#14 Post by robbie1003 » Thu Dec 08, 2016 9:37 pm

severity of vsr also depends on type of driving its had ,ours was mainly start stop during the week as otherhalf uses it for out of hours community nursing, the odd long run towing but by that time iv fitted valve lube system.

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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#15 Post by LPGC » Thu Dec 08, 2016 10:15 pm

Can't beat a retro thread :lol:

VSR was only an issue on V8 Jeeps fitted with certain LPG systems such as Piro and Prins. Piro has an issue that prevents correct fuelling around 3000rpm and a lot of Prins installers probably followed instructions to 'use these settings and these injectors' which then provided incorrect mixture. Also didn't help that some installers fitted manifold nozzles too high.

Different subject but just removed a single point system and fitted sequential on a highly modified 4L Jeep Wrangler for 'East Coast Customs'.

Simon
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Morat
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Re: Converting a Jeep Grand Cherokee WJ 4.7 HO (Overland)

#16 Post by Morat » Tue Dec 27, 2016 12:31 pm

Haha definitely retro.
This was the start of the journey that ended with the P38 you converted a while back. It's a fun old bus but my wife hasn't bonded with it. I think we'll keep hold of the Rangey but she's hankering after something faster and manual. Women are great :) She's talking about something golf sized, I'd rather go 1 series but they don't have spare wheel wells from what I've seen :(

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