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As you may know the changeover from leaded to unleaded has been bad for the FWD. It starts ok, and runs fine for a little while, but then becomes utterly gutless and sounds like a milk churn full of spanners rolling down a flight of stairs. However, a change back to leaded solves the problem instantly.

 

So we have tried:

mixing unleaded with paraffin

Fitting an external fuel pipe in case the petrol was getting too hot

Changing the jet on the carb.

 

None of this has worked. The next suggestion is to adjust the timing. Now as the thing runs fine with leaded, is it feasible that the timing would need to be changed for unleaded? Chapter 8 ("Troubles and remedies") of the manual for the Motor Supply Train (pub 1918) would suggest that this is a good remedy for the symptoms we are suffering. What are the thoughts of this most knowledgable band of brothers?

 

Tim (too)

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Are you not confusing red diesel with 28 second burning oil which is essentially kerosine?

 

Maybe. Not sure of the different types of heavy oil. But either or I think the same applies as long as you pay the current level of duty for road fuel then you can run on it.

 

Used to be the same with homemade biodiesel you had to declare it to customs and pay duty, but a discounted rate. Now I think it's duty free for home made bio, for the first 2500 litres or thereabouts.

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I have been following this with much interest.

Although my ferret is running a whole lot better than it ever has, it still runs badly, with loss of power when hot. I have noticed the exhaust manifold glows cherry red, and a lot of the things said here sound exactly like whats happening to mine.

I am about to order up some of these :

http://cgi.ebay.co.uk/JAGUAR-E-TYPE-XJ6-XK-ETC-RUN-ON-95-UNLEADED-UPTO-4200CC_W0QQitemZ180331511857QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item180331511857&_trksid=p3911.c0.m14&_trkparms=66%3A2%7C65%3A1%7C39%3A1%7C240%3A1318

 

I'll keep you posted

Mick

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Steve,

 

Would it be possible to fit an insulator gasket between the carb and manifold? Also wrap the fuel lines adjacent ot the engine in asbestos string.

 

Have you been in contact with any veteran car owners, as some of them may be experiencing this?

 

Hi Richard.

 

The heat problem seems to be a feature of the layout of the lorry. The rad and fan are at the front but the engine is under the seat so there is no air flow past it at all. The tank is on top gravity feeding through copper pipe and a big brass filter all within the engine space so it has a lot of opportunity to get hot. My trial cure was to run a plastic hose around the outside and up underneath and this seemed to sort it. If it should prove to be a major part of the solution, I will run a copper pipe outside the engine space and up under the chassis just next to the carb. It won't be as original but an acceptable fix, I think. I had thought about wrapping the pipe inside the bay but am concerned about forming a wick to soak up leaking fuel. I really don't want to add to the fire risk if I can help it!

 

I have spoken with a variety of veteran vehicle people but none have come up with this trouble. Even our Autocars seem to be completely immune to any effects of changing the fuel so I am beginning to think there is another problem as well. I am suspicious of the magneto and would like to try our spare. Unfortunately, I just ran out of time on Sunday as I had to drive back. It really is a pain living 200 miles from our project!

 

Cheers!

 

Steve

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Hi Steve, what's the chances of the problems being your plugs not coping with the differences in fuel?

 

Not sure about plugs as I just don't have enough knowledge. I would expect them to be fairly insensitive as the engine only runs at 1400rpm on a compression ratio of 4:1 but I would be very pleased to hear some advice. Going from memory, they are new Champion C5, 18mm and WD stamped!

 

Steve

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Isn't there a surface coating used on high performance vehicles to aid heat disapation of manifolds etc?

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Have you got (if it uses one) a head gasket or valve problem? Only when the Champ went on the road for the first time Lots of running problem no power when hot and two split silencers due to a blown head gasket.

 

This lorry has no head gaskets so that is one problem eliminated! Compression is fine with none of the cylinders leaking. (One advantage of a hand-cranked engine!). I have also checked the tappet clearance on the inlet side to make sure the valves are opening fully and they are OK too. I need to look at the exhaust side but couldn't get in on Sunday as the toolbox is in the way. Something to check next time.

 

Cheers!

 

Steve

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Not sure about plugs as I just don't have enough knowledge. I would expect them to be fairly insensitive as the engine only runs at 1400rpm on a compression ratio of 4:1 but I would be very pleased to hear some advice. Going from memory, they are new Champion C5, 18mm and WD stamped!

 

 

 

Steve,

 

Even new plugs fail, quite often at that. When I was an agricultural engineer in the Sixties, we still did quite a few petrol paraffin tractors and combine harvesters. When drawing new plugs from the stores, before travelling out to the farms, we would test them on the test rig ( either Champion or AC tester), it allowed the plug to spark and as the pressure was raised to simulate the cylinder pressure, you checked to see if the plug was breaking down. It was not at all unusual to have (Champion!) plugs out of the packet, failing. So it is worth swapping plugs if you have any spares.

 

Also, just had a thought, perhaps the plug grade is not quite right. A problem with 18mm, as there is not a large range available in this size anymore. Did you select C5 as being nearest to correct, or is it the only one in that reach that was available? The grades run from hot to cold and have a huge influence on running.

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That compression is very low! modern petrol probably gets in the cylinder, goes bang instantaneously and then doesnt produce any slow burn power for the rest of the stroke that lower octane fuel would provide, just heats up the cylinder until it eventually get pushed out of the exhaust. Im still going with the Octane thing being the problem!

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The following is the Petrol octane ratings prior to WW2:-

Here is an excerpt from the Ferguson tractor guys, they used to use a mix called TVO (Tractor Vapourising Oil) no longer available for sale, but it has alot of applications in other older vehicles:-

.......

 

Thanks for that. That is the best fuel mix description I have ever come across! That gives us another string to our bow after I have tried the new mag.

 

Cheers!

 

Steve

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Post back how you get on with it, like ive said i had good results with it, but its always worth knowing how others get on with stuff like this!

 

Now off to siphon the heating oil tank!:cool2:

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Thanks everyone for so much good, constructive and helpful comment. It is very easy to get despondent when one has spent an hour swinging on the handle, the lorry is beside the road and still won't go and you've got to get in the car for a four hour run back home. I am going to make a new impulse trigger for the spare mag (whilst the same model as before, it is not quite the same!) and plan to have another go next weekend if I can get down. I will keep you all posted with the results.

 

Cheers!

 

Steve

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Steve, at one point you mention the carb iceing on the outside, and also back firing enough to destroy the silencer.

the question I would ask is if you leave the FDW stood for say half an hour will it start and run for a short time?

When we gave up on LRP and went ot ULP on out 1931 MG race car, we suffered almost identical problems, which in the end turnned out purely to be carb icing, the ice on the outside cleared as the engine warmed , but above the main jet (downdraft su) we had a pancake of thin white ice and the engine was running so rich it had no power and an inferno in the exhaust! This took an age to find as I had never though of looking down the throat of the carb and by the time I was looking at the carb it would have melted.

Anyway a chap who I race hstoric formula 3 with works for a petrol co. as a chemist and he said it was due to the mix of unleaded (he did tell me the technical reasons but it went way over my head as you couldn't fixit with a hammer!)

 

Richard.

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We have had a new development! Father has tried to crank the engine and found it solid! It turned when we parked up but has seized as the engine has cooled. Father crawled underneath and tried turning the flywheel backwards and it has moved a bit but very little so the pistons and main bearings are free but it is sticking elsewhere. Holding the clutch down has no effect so we are reaching the conclusion that some of the valves have stuck. He will try slacking off the tappets on the exhaust side tomorrow and see if the engine will turn any more. If it does turn then they are our problem.

 

Now, this is my hypothesis as to what has happened. Dad has made new valve guides and we had new valves made to match. As a result, they are a lovely close fit. This is a side valve engine with no valve stem lubrication at all. Up to now, the lead compounds have kept it all moving but with unleaded fuel, these have gradually disappeared. The unleaded fuel has also been causing the engine to run lean and therefore hotter so I would suggest that the combination of extra heat and lack of lubricant is causing the valves to stick open or be very slow to close thus causing all this backfiring. Any thoughts please?

 

Assuming that this is the problem, I need to resolve the lean running and use a suitable fuel additive, not for the octane but for lubrication purposes. Has anyone any further experience of additives please? I am not sure that the fuel catalyst type will help this problem.

 

Of course, I may be barking up the wrong tree!

 

Steve

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Steve, at one point you mention the carb iceing on the outside, and also back firing enough to destroy the silencer.

 

 

Hi Richard.

 

The ice doesn't seem to cause it any serious problem starting or running. It is so hot in the engine bay that it soon goes. What is interesting to me is that the condensation can be seen and it begins to freeze as soon as the engine is started which it didn't do with leaded fuel. (At least, I never noticed!).

 

There are quite a lot of clues here as to what might be going on. I just need to interpret them and with all of your help, I think we are getting there. I certainly have plenty of avenues to explore. First priority is to get it to turn again!

 

Steve

DSCN9770c.JPG

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Now, this is my hypothesis as to what has happened. Dad has made new valve guides and we had new valves made to match. As a result, they are a lovely close fit. This is a side valve engine with no valve stem lubrication at all. Up to now, the lead compounds have kept it all moving but with unleaded fuel, these have gradually disappeared. The unleaded fuel has also been causing the engine to run lean and therefore hotter so I would suggest that the combination of extra heat and lack of lubricant is causing the valves to stick open or be very slow to close thus causing all this backfiring. Any thoughts please?

 

Assuming that this is the problem, I need to resolve the lean running and use a suitable fuel additive, not for the octane but for lubrication purposes. Has anyone any further experience of additives please? I am not sure that the fuel catalyst type will help this problem.

 

Of course, I may be barking up the wrong tree!

 

Steve

 

The TVO type mix should help with valve lubrication. I'd be trying it before any of the `snake oil' systems.

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The simplest way to improve lubrication would be to add some two stroke oil to the fuel as this is what it is specifically designed for. Most modern two strokes use a 50 to 1 mix and run at very high revs, but with your slow revving engine I would have thought that a very small amount would be sufficient. It might be worth speaking to the technical dept at Morris Oils, they are very knowledgable and usually very helpful.

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Degsy, would ading two stroke oil affect the Octane rating? I'm wondering if this might be a good idea in gentral older motors. I have run my Gipsy and Landy's over the years on top ups from the chain saw two stroke mix with no apparent problems. satandard in them days was about 16:1

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I wouldn't have thought that the small amount of oil added would have any noticeable effect on fuel octane ratings but there again I am not a petroleum engineer which was why I suggested speaking to Morris's.

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hi steve,

 

with regards to petrol additive, if i run my hotchkiss jeep with no additive the carb float sticks and floods the carb, i know of 3 people with jeeps locally and they dont use additive and have no problems:confused:, the additive i use is from morris oils and it works for my jeep and its reasonably priced too

regards

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Thanks chaps. I will get in touch with Morris's. They have always been very helpful in the past but I never thought of asking about fuel additives.

 

Cheers!

 

Steve

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Thanks chaps. I will get in touch with Morris's. They have always been very helpful in the past but I never thought of asking about fuel additives.

 

 

 

 

Steve,

I have used Morris's Superblend Zero 2000 lead replacement additive for many years, using it in my Bedford and supplying to many other people for their MV's and classic fire engines. It was the best performing lead replacement additive in the tests conducted at MIRA.

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Guest catweazle (Banned Member)

I use it, crank that distributor round, in many cases it means you dont have to retard the ignition,i keep advancing it up till it pings then just back it off a touch.Also add the water absorbing addative as the car stands around a lot.Both these items cured Lord burleys problems on his Ferret.

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Hi Catweazel,

 

what problems did Lord B have with his ferret?

 

I added the fuel catalyst to my Ferret at the weekend, but have not started her up just yet. I'll be interested to see if it makes any difference :)

 

Mick

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Of course, I may be barking up the wrong tree!

 

Well, I am down in Devon and it does seem that I have been barking up the wrong tree! After pushing off the remainder of the snow yesterday, we unsheeted it and I gave the handle a turn. It stopped with a 'clonk'. Dad had previously backed off the tappets and all of the push rods were free so it wasn't the valves. The clutch was held down so it couldn't be the gearbox. The only other things driven by the engine are the fan, magneto and water pump. I couldn't see a problem with the pump and the fan was free so this left only the magneto which was strange as I had removed it the last time I was down! It turned out that when I had taken it out, the coupling had dropped out and I hadn't noticed. It was left leaning against the drive dog which it managed to jam when the engine was turned. I simply lifted it out and that problem was solved. One down!

 

I then put the magneto on the running board and gave it a flick whilst holding one of the leads nearby. I obtained a reasonable spark. A second flick caused another, much weaker, spark which was a surprise as I would expect only one spark every second revolution from any lead. All four leads were the same giving a good spark followed by a weak one. Our spare mag gave one good spark every second rev as I would expect so I fitted that back on the engine and re-timed it all.

 

We reset the tappets, added some more fuel, this time with a shot of Redex which one of had bought and forgotten about, and then tried to start it. It fired on the third compression and sounded a completely different animal. We went for a run down the road and it went very well. At last it was nice to drive! We did a couple of miles and all was fine so I decided to try and run it back on the internal fuel line. You may remember that my original thoughts were that the fuel was getting too hot and causing it to run lean so I had rigged up an external line outside the engine bay. I reconnected the original fuel line and we had another go. It would not start! We swung and swung but it didn't want to know. After about 40 minutes, it chuffed and then burst into life but it was rough as rats and popped and banged something terrible. We left the side panel off and I set off towards home. It got better after a while, as it cooled off, and I got it into the driveway and back in its shed without a problem although it was still rough.

 

From all of this, I think there have been three problems. The magneto had a fault to start with, one of the exhaust tappets had too big a clearance and the more-volatile unleaded fuel tends to vapourise in the carb giving us too lean a mixture. The magneto and tappets, we have sorted. Todays project is to make up a proper external fuel pipe, with lagging, to prevent the fuel from being heated. We are also going to use an additive to help the valve stem lubrication. After all that, it is fingers crossed for Brighton!

 

Many thanks, everyone, for all of the great advice and assistance offered here. Once we have our new fuel pipe fitted, I will let you know how we get on.

 

Cheers!

 

Steve

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