Hi
I have available a 4.2 LWB Range Rover Classic, from which I am thinking of taking the engine out of to fit to a Series 1 Land Rover. I'm pretty sorted out with the conversion plate, mounts, oil filter block, transmission and Stage 1 V8 Axle (already converted for a Seres 1), but would like to seek any advice on the fuel system as I'm changing this to Twin SU HS6's from a 3.5 V8.
Why? Retro and simpler, and easier/cheaper to LPG with the suppliers I have here in the South West.
The engine is getting its first start (attempt) in the chassis this week, and after that it'll be removed with all the pipework and ancillaries feeding the engine. Then checks and things like new valve stem oil seals, compression checks, etc, whilst it's out on a stand before fitting to the Series.
The exhaust will be cut down and fitted 'as is' until I have sorted out a suitable replacement, and then the LPG goes on as the last thing.
Has anyone converted a 4.2 or similar this way? I searched the forum and all over but it's all about getting more and going faster, I need less and less in those respects for my needs, so I seem to be on my own. It's a project to get a classic V8 thing going at the end of the day.
Loads of great twin SU info on here, so will appreciate that when head scratching.
I should (if the info isn't out there) run a thread on this maybe to keep the information worked out ready for the next person looking at this.
Thanks in advance.
4.2 EFI Converting to Twin SUs
Moderator: phpBB2 - Administrators
Hi
I wouldn't put LPG on a 4.2 engine without increasing the compression a lot. The 4.2 is a low compression engine (from memory about 8.13:1) for LPG to begin to burn properly you want a minimum of 10.5/11:1 even then much more would be better. You will find it will work sort of for a short while then it will start burning out exhaust valves and seats and back firing. You can't add enough timing to crutch it into working as the engine will then start cross firing onto other cylinders on over run (see other posts on the subject).
Best regards
Mike
I wouldn't put LPG on a 4.2 engine without increasing the compression a lot. The 4.2 is a low compression engine (from memory about 8.13:1) for LPG to begin to burn properly you want a minimum of 10.5/11:1 even then much more would be better. You will find it will work sort of for a short while then it will start burning out exhaust valves and seats and back firing. You can't add enough timing to crutch it into working as the engine will then start cross firing onto other cylinders on over run (see other posts on the subject).
Best regards
Mike
poppet valves rule!
Got a bit further with the compression ratio, some good posts on here explaining why LPG needs it, and the best way for me is to use the older thinner tin head gaskets or use 4.6 heads. Don't want to be changing any pistons, etc.
On the engine I have, it looks like the unit was just used in the Range Rover LSE version of the Classic Range Rover. 4.2 litre displacement is actually 4,275 cc (260.9 cu in), and used the crankshaft castings from the failed Leyland Iceberg diesel engine project. Bore remained the same at 94.0 mm (3.70 in), but stroke increased to 77.0 mm (3.03 in).
The data shows with the Bore x stroke: 94.0 mm x 77.0 mm (3.70 in x 3.03 in) , giving a Compression Ratio of 9.35:1, which is a bit shy for LPG.
I'm thinking Tin gaskets and mappable ignition (change between petrol and LPG running) might be the option, going to a change to 4.6 heads if the compression ratio isn't enough and the valves burn and performance drop off.
Interesting stuff!
On the engine I have, it looks like the unit was just used in the Range Rover LSE version of the Classic Range Rover. 4.2 litre displacement is actually 4,275 cc (260.9 cu in), and used the crankshaft castings from the failed Leyland Iceberg diesel engine project. Bore remained the same at 94.0 mm (3.70 in), but stroke increased to 77.0 mm (3.03 in).
The data shows with the Bore x stroke: 94.0 mm x 77.0 mm (3.70 in x 3.03 in) , giving a Compression Ratio of 9.35:1, which is a bit shy for LPG.
I'm thinking Tin gaskets and mappable ignition (change between petrol and LPG running) might be the option, going to a change to 4.6 heads if the compression ratio isn't enough and the valves burn and performance drop off.
Interesting stuff!
-
unstable load
- Top Dog
- Posts: 1279
- Joined: Mon May 04, 2009 6:53 am
Explain why everybody here in Holland is running LPG in their seventies US car. They are all LC smog engines. Never had issues.kiwicar wrote:Hi
I wouldn't put LPG on a 4.2 engine without increasing the compression a lot. The 4.2 is a low compression engine (from memory about 8.13:1) for LPG to begin to burn properly you want a minimum of 10.5/11:1
Mike
Most of them use Impco systems but that should make the difference.
LPG is cheap and runs great even in an LC engine. ( LPG is half the price of regular 95 here )
LPG has indeed a high 100+ octane rating but doesn't have the energy rating compared to fuel.
Run LPG myself in my 70's F250 truck ( 400 V8 ) it still goes like stink and it doesn't matter if I towing my trailer with Capri behind it, even with this combination fully loaded I can keep in front of many so called GTI's with the traffic light sprints.
LPG runs fine on a LC engine.
'73 Ford Capri. 3.5 RV8, Magnacharger 110 Supercharger, Merlin F85 Heads, Water/Methanol Injected
'73 Ford F250, 6.7ltr V8
Building a GT40 mk2
'73 Ford F250, 6.7ltr V8
Building a GT40 mk2
Hi JP
it must be I am making it up!
and the issues I had with my RR on LPG were all in my head.
Sorry but I have been over and over this on this forum and am only trying to save the OP some misery.
The reality is original car manufacturer sell virtually no LPG cars compared to diesel or LPG because they have to offer a warranty on their engines. If it was any good as a fuel then car manufacturers sell cars that ran on it and the government would not put 50% of the duty on the stuff and everyone would use it, the stats tell the story!
Best regards
Mike
it must be I am making it up!
and the issues I had with my RR on LPG were all in my head. Sorry but I have been over and over this on this forum and am only trying to save the OP some misery.
The reality is original car manufacturer sell virtually no LPG cars compared to diesel or LPG because they have to offer a warranty on their engines. If it was any good as a fuel then car manufacturers sell cars that ran on it and the government would not put 50% of the duty on the stuff and everyone would use it, the stats tell the story!
Best regards
Mike
poppet valves rule!
All cars aged 25 years & + where tax exempt in Holland.
LPG costs only half the price of regular 95 fuel making LPG is very popular on classic cars over here, mainly on heavy consuming US cars. Till two years ago every body was converting their old cars to run on LPG, mainly using Impco systems ( easy fit on one, two and four barrel carb ).
So you had no tax, cheap insurance and cheap fuel.
Nowadays since 2014 rules have changed. Cars have to be 40 years now to be tax exempt including the cars that where between 25 & 40. Cars between 25 & 40 can not run diesel or LPG now or you have to pay max price on tax ( triple fuel tax for LPG or twice fuel tax on diesel ).
So everybody with a car between 25 & 40 is taking it out for the moment waiting till the car is 40 to put it back in.
Mine is a '73 so I have no issues. The smog 400 V8 is even running better and has a slightly lower consumption on LPG.
Edelbrock intake, Holley 600, MSD ignition Impco 300A LPG system
So on a Rover engine, best combo is, Edelbrock or Offenhauser intake with a knackered Holley carb ( doesn't have to work as you run LPG ) and an Impco 300A or instead of the carb use an Impco 425 Mixer on in.
You need the intake for the Holley carb pattern.
LPG costs only half the price of regular 95 fuel making LPG is very popular on classic cars over here, mainly on heavy consuming US cars. Till two years ago every body was converting their old cars to run on LPG, mainly using Impco systems ( easy fit on one, two and four barrel carb ).
So you had no tax, cheap insurance and cheap fuel.
Nowadays since 2014 rules have changed. Cars have to be 40 years now to be tax exempt including the cars that where between 25 & 40. Cars between 25 & 40 can not run diesel or LPG now or you have to pay max price on tax ( triple fuel tax for LPG or twice fuel tax on diesel ).
So everybody with a car between 25 & 40 is taking it out for the moment waiting till the car is 40 to put it back in.
Mine is a '73 so I have no issues. The smog 400 V8 is even running better and has a slightly lower consumption on LPG.
Edelbrock intake, Holley 600, MSD ignition Impco 300A LPG system
So on a Rover engine, best combo is, Edelbrock or Offenhauser intake with a knackered Holley carb ( doesn't have to work as you run LPG ) and an Impco 300A or instead of the carb use an Impco 425 Mixer on in.
You need the intake for the Holley carb pattern.
'73 Ford Capri. 3.5 RV8, Magnacharger 110 Supercharger, Merlin F85 Heads, Water/Methanol Injected
'73 Ford F250, 6.7ltr V8
Building a GT40 mk2
'73 Ford F250, 6.7ltr V8
Building a GT40 mk2
Mike and I disagree on this one!
I have been running LPG for years. Currently I'm running a P38 Range Rover, which is 9.37:1 on LPG. So far (50K miles), no LPG related issues, in fact, the LPG system has been fabulous.
There is slightly less power on LPG, but it's no big deal. You can always switch back to petrol if you need the power. Doing this on carbs isn't so easy though!
Definitely do not go with tin head gaskets. They are poop, there is a reason that Land Rover eventually binned them. Composites with 10 bolts per head is the answer.
Raising compression ratio is much better done with the pistons. If you skim the heads too far from factory spec (allowing for the head gasket thickness), then the valve preloads move out of spec, and it becomes a nightmare getting it all right again.
Chris.
I have been running LPG for years. Currently I'm running a P38 Range Rover, which is 9.37:1 on LPG. So far (50K miles), no LPG related issues, in fact, the LPG system has been fabulous.
There is slightly less power on LPG, but it's no big deal. You can always switch back to petrol if you need the power. Doing this on carbs isn't so easy though!
Definitely do not go with tin head gaskets. They are poop, there is a reason that Land Rover eventually binned them. Composites with 10 bolts per head is the answer.
Raising compression ratio is much better done with the pistons. If you skim the heads too far from factory spec (allowing for the head gasket thickness), then the valve preloads move out of spec, and it becomes a nightmare getting it all right again.
Chris.
--
Series IIA 4.6 V8
R/R P38 4.6 V8
R/R L405 4.4 SDV8
Series IIA 4.6 V8
R/R P38 4.6 V8
R/R L405 4.4 SDV8
Hi Guys,
All good info - many thanks.
Yes I had a P38 on LPG without any problems for 4 years, that makes sense to me, and thanks for the lead on the tin gaskets; composite and 10 bolts it will be.
Probably best to get the engine onto carbs and LPG'd as it is, and see where things go. I don't want to be changing pistons if I can help it, but I might track down some 4.6 heads and refurbish them 'just in case'.
This engine is going to be pushing a Series 1 Land Rover down the road, so I'm not after revs or oodles of power, just the torque and the V8 sound is what we're after.
Yes cutting across from Carbs/Petrol to LPG can be a hoot - having to drain the bowls before cutting over, interesting stuff, but I expect she'll be running on LPG 99.9% of the time, we'll see what the art of the possible is.
I'm using the 4.2 engine instead of the 3.5 as it is free so long as I get the owner some cash for the car interior, etc, before it's scrapped. He's being very generous with this, no doubt there - I think he wants to see the engine out again as a daily driver, can't blame him.
All good info - many thanks.
Yes I had a P38 on LPG without any problems for 4 years, that makes sense to me, and thanks for the lead on the tin gaskets; composite and 10 bolts it will be.
Probably best to get the engine onto carbs and LPG'd as it is, and see where things go. I don't want to be changing pistons if I can help it, but I might track down some 4.6 heads and refurbish them 'just in case'.
This engine is going to be pushing a Series 1 Land Rover down the road, so I'm not after revs or oodles of power, just the torque and the V8 sound is what we're after.
Yes cutting across from Carbs/Petrol to LPG can be a hoot - having to drain the bowls before cutting over, interesting stuff, but I expect she'll be running on LPG 99.9% of the time, we'll see what the art of the possible is.
I'm using the 4.2 engine instead of the 3.5 as it is free so long as I get the owner some cash for the car interior, etc, before it's scrapped. He's being very generous with this, no doubt there - I think he wants to see the engine out again as a daily driver, can't blame him.
