andypike Posted August 22, 2015 Share Posted August 22, 2015 Hi everyone Im looking for some help we have just brought a 1972 series 3 that was a petrol and was converted to diesel at some point the problem we have is that its top speed is about 40-45 mph is there any thing we can do to make it go faster or was there a gearbox for petrol and one for a diesel sorry if we sound silly just would like to no . thanks yours andy Quote Link to comment Share on other sites More sharing options...
Arjan Posted August 22, 2015 Share Posted August 22, 2015 Hi there - welcome here. Are you sure the red lever is pushed fully forward - sounds almost like it is in low range. Is the throttle fully opening ? The gearboxes for diesel & petrol are the same AFAIK.. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted August 22, 2015 Share Posted August 22, 2015 Hi Andy, As Arjan says: Same 'box in both. Assuming that it is still a series engine and gearbox - pop a photo up and we'll confirm. There are many fans of the 2286 diesel, but I'm not one. Gutless, soft and underpowered in my experience. Too much slop in the timing for a diesel. Unless you NEED economy I'd put the petrol back in. If you do need more speed then consider an overdrive (a fifth gear) but the engine will struggle with the extra loading necessary on anything other than the flat. G. Quote Link to comment Share on other sites More sharing options...
Les Henson Posted August 23, 2015 Share Posted August 23, 2015 You are down by about 40% of top speed (a little over 70mph from the factory). Simple things to check first - throttle adjustment, lift pump working (you lose higher revs if it isn't working. Pump timing (pillar type rotates a small amount to adjust timing). Tappets adjusted correctly (if they are too tight, then you will lose power). Could be a very worn engine, but a compression test isn't really a DIY thing as diesel compression testers are expensive. They are not a particularly a good engine, as they have to work hard to get you from a to b. The 2.5 N/A engine is a good replacement and was a popular conversion some years ago. The TD was as well, but they have a bad habit of cracking pistons.You can fit other engines, such as TDi or v8, but it's quite a bit of work to fit them. Les. Quote Link to comment Share on other sites More sharing options...
secondjeremy Posted August 26, 2015 Share Posted August 26, 2015 Have you got a proper Land Rover diesel engine or something else? Some Perkins (and others no doubt) don't rev very fast. Otherwise - make sure the throttle is opening fully. They can get sticky or be badly set up. If you've got the cable one (little short cable to the pump) make sure the outer cable is sitting properly in its clamps - if someone's been fiddling with the cable its easy to dislodge. 88in on standard (600 x 16 or 205 x 16's) should do about 60 in top - LWB - about 65 (I've seen it!) Quote Link to comment Share on other sites More sharing options...
deep Posted August 26, 2015 Share Posted August 26, 2015 My old Series III diesel was governed to around 60 m.p.h in top (it wouldn't even go faster downhill) but it got there within a minute or so with standard gearing. The big question is: is it revving its heart out at 45m.p.h (suggesting it's not actually a Land Rover diesel, or that you have tiny little tyres on it) or is it just no power (suggesting one of the things mentioned above or, very likely, a clogged filter or line? Quote Link to comment Share on other sites More sharing options...
LaRoNut Posted August 28, 2015 Share Posted August 28, 2015 Regardless of the type of diesel engine....the rpm will be the same at 45MPH, unless something else on the drive-train or tyre size has been changed. You probably have an under-performing engine if it's the 2.25 from Land Rover, as you should get over 60MPH on a slight downhill Quote Link to comment Share on other sites More sharing options...
deep Posted August 28, 2015 Share Posted August 28, 2015 Regardless of the type of diesel engine....the rpm will be the same at 45MPH, unless something else on the drive-train or tyre size has been changed. You probably have an under-performing engine if it's the 2.25 from Land Rover, as you should get over 60MPH on a slight downhill Some more agricultural diesels hit the wall at under 3,000 r.p.m.. They'd be finished by 45m.p.h.! I wasn't that clear, sorry. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted August 29, 2015 Share Posted August 29, 2015 Some more agricultural diesels hit the wall at under 3,000 r.p.m.. They'd be finished by 45m.p.h.! I wasn't that clear, sorry. Ditto marine engines - lighter crank and pistons as a result. Quote Link to comment Share on other sites More sharing options...
DaveSIIA Posted August 30, 2015 Share Posted August 30, 2015 One-tonne Series LWB were fitted with a lower high range transfer gear. Could the box have been swapped at some point or might it be a One-tonne LWB (OP doesn't state vehicle)? Quote Link to comment Share on other sites More sharing options...
deep Posted August 30, 2015 Share Posted August 30, 2015 One-tonne Series LWB were fitted with a lower high range transfer gear. Could the box have been swapped at some point or might it be a One-tonne LWB (OP doesn't state vehicle)? True. I drove a IIb forward control once which had a 3 litre motor fitted and it was screaming at 45m.p.h.! Those ratios are rare though. Quote Link to comment Share on other sites More sharing options...
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