I’ve been using LPG for over 15 years and had intermittent issues with various cars. I’ve got a SC in the stable now and there’s no way I’m going to convert that for the reasons Lighthouse alludes to despite having a brand new Prins system and the coding software. I did put hardened valves into one of my cars once but it was the head that then went, and not the valves, again as Lighthouse says happened to him.

I think if you’re going to buy a SC, run it for what it is, but if you want to use LPG, get a 4.4M62 BMW unit.

Regards

John

The BMW 4.4 are fine to convert no issues with those ones.

I just added a 5.0 late L322 to my stable and I am leaving it 100% petrol if you work out the cost of 2 heads or hardened valves you have to do one hell of a lot of miles to offset the fuel cost.

As for why I scaped it was at the point that it was a 2006 car, worth 4K ish and I would have had to spend at least it’s own value to fix it, then you still have all the other things that come with a 15 year old motor like older controls and style. So I scraped and have spent the last 11 months looks for a decent late L322 that has all the things I want.

Like I said before I am not anti LPG it’s great I had my own skid was excellent value in terms of fuel cost. It’s just you need the right engine and the post 2006 SC’s in the range are not them. If your talking BMW lumps I’m the range go for it will be awesome.

It was a sad day saying good bye to a range that you had driven over 60000 miles in and had killed.

Like I said I’m not expert just an amateur who likes to play with his stable of cars from classics to modern day motors.

Whatever you decide good luck and if you do convert an SC flash lune turned to highest injection rate and never let it run out and at least 1 in 4 petrol tanks.

Danwilderspin wrote:

Lighthouse - wouldn’t it have been worth getting the buckets done or new seats hardened seats fitted rather than scrap it?

Yea the bmw engine does - I didn’t realise that the jag ones were that retro and weren’t.

Not sure about the rest of your question but a guy called Matt on here is doing a full tear down and rebuild.

What symptoms do you have and mileage and is it on gas? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

I have no issues on gas, but I intend on keeping it that way. I'm at 140k miles but only 10k on gas. Have lots of experience of other gas cars, but rr are new to me.

So are you doing tappets now or getting preemtive advise? Do you have a lube system? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

I would like to check and or adjust the clearances but as I'm not sure what the clearance settings should be, or have access to a tool to depress the bucket to swap out the shim and also have access to a number of different thicknesses of shim im a bit stuck. I suspect this is how theses engines get the reputation of being soft, as once there is any wear on the valve or seat you quickly use up the clearance which is probably already compromised and then you burn seats and valves. Checking and resetting this clearance would stop this issue. The intervals would be determined through experience. I would be grateful to anyone who can assist with:

Confirm the factory inlet and exhaust clearance
Have access to a shim kit or just shims they could rent and or sell.
Are the shims used in other engine's?
Confirm the tool required to depress the edges of the bucket. I believe this bolts in place of a cam cap? Or even a drawing that could be used to make our own?

Yes I'm using valve lube. First engine I have ever used it on. I'm really an Audi turbo guy and they love gas. Hard valves, seats and hydraulic tappers. A winning combination.

VSR is an issue for all Jag V8's and to a degree their straight six..

A flashlube system comes highly recommended, and works well on the AJv8..

Diesel des wrote:

Danwilderspin wrote:

Lighthouse - wouldn’t it have been worth getting the buckets done or new seats hardened seats fitted rather than scrap it?

Does anyone know where you can get shims to do a valve clearance reset on a 4.2 SC V8? Also I have heard you can use a tool from the 3.0v6 Jag to compress the bucket to allow access to the shim. Is this true? What clearance are people using?

I suspect that checking and resetting the clearance periodically would make a massive difference to valve life on Lpg. Doesn't the BMW engine have hydraulic tappers so they self adjust..

The engine gets quieter as the valve clearance reduces. I would be ok with some mild valve noise, with a larger than stock clearance. This also helps with the perceived heat issue. It's not heat that causes the issue in the first instance, it's a lack of clearance causing the hot combustion gases to get past the valve and seat before the piston has moved down the bore which allows the gas to cool through expansion. A tight valve seal will impart less heating to the valve as gas passes it on the exhaust stroke only. Also a good seal gives a large surface area for the valve to dump heat into the seat and head when it's closed.

Do you know if shims from other Jag engine work in this application? Also what about tooling? Cheers

I found this in the manual. Does anyone have access to the shims referenced?

I was browsing the web tonight and came across water injection kits to lower the temperature of the combustion chamber.

They get great reviews and was wondering if this could greatly reduce vsr? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Possibly, but it's more of a power adder on turbo engines,eg water/meth injection. It suppresses detonation very effectively. Not sure it's the ideal fix for not adjusting valve clearance sufficiently often to stop the valves burning. If the valves always have clearance they won't burn. They may erode at a faster than normal rate, but still provide a good service life. Running on Lpg needs more frequent inspections and possibly adjustments, at least more than never, that seems to be how theses engines get neglected. This is why the BMW engine with its hydraulic adjusting tappets is considered bomb proof.


I can confirm the followers on the aj V8 are the same as the 3.0 V6 as I have bought some of both to compare. I have also bought the tool to depress the follower and change the shim. But haven't had a chance to get into her yet.

I have recently changed my engine (not due to LPG problems) it had done 20,000 ish miles on LPG and I couldn’t see any wear related problems with intake or exhaust valves in fact they were spotless

So, just an update. Details in the thread below.

https://www.lpgforum.co.uk/viewtopic.php?f=33&t=16575

To summarise, the AJ V8 engine in the range rover, at least my 2006 supercharged one, has non adjustable valve clearances. The bucket follower is all one piece, and to change these to thicker or thinner buckets requires the cams to be removed, which is quite an involved job. It's one I got very busy with as I had to remove both heads etc as I had valve clearance issues. It would appear even on petrol some engine's, particularly supercharged ones, due to the hot intake and low efficiency charge coolers, end up with no intake valve clearance and loose compression on a cylinder.

The first you know about it is a cold missfire that goes away when warm.

Anyhow I had both heads rebuilt with all new valves, Lpg compatible seats, and some extra clearance dialed in. She's a good job now, but not cheap.

CHECK YOUR VALVE CLEARANCE. Should be 0.2mm intake, 0.25 exhaust. Yes you need to pull cams to adjust, but that's easier than pulling heads. You have been warned.