Mr Bean Posted September 30, 2008 Share Posted September 30, 2008 I am thinking of upgrading my 3.5 V8 on carbs to a 3.9 EFI. I was going to buy a rotten Classic or a Disco as a donor. Hopefully i can find one with LPG at the same time. The swap of engine and wiring loom seems relatively straight forward but the questions are: 1. Will it fit straight onto the existing 5 speed gearbox? 2. What about the fuel lines and the fuel tank? What tank do i use and do i need to plumb in a return fuel line as well? Many thanks, Quote Link to comment Share on other sites More sharing options...
paul stage1v8 Posted September 30, 2008 Share Posted September 30, 2008 yes they are basically the same engine block so bolt patterns are the same is your pump in the tank or on the chassis? an in tank pump is easiest, just use an early disco/ RR pump (tank as well if yours doesnt take a pump) and an efi filter. Quote Link to comment Share on other sites More sharing options...
bluespanner Posted September 30, 2008 Share Posted September 30, 2008 Couldnt you bolt the carbs to the 3.9? Quote Link to comment Share on other sites More sharing options...
paul stage1v8 Posted September 30, 2008 Share Posted September 30, 2008 he could but it seems he wants EFI, I am using carbs on mine as my lpg setup is for carbs and I dont want the electronics. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 1, 2008 Share Posted October 1, 2008 Couldnt you bolt the carbs to the 3.9? That is such a horrible idea in so many ways. You may as well try to run it on diesel while you're at it. Quote Link to comment Share on other sites More sharing options...
Mr Bean Posted October 1, 2008 Author Share Posted October 1, 2008 I happen to like EFI. Do we think this is a good or bad idea? Quote Link to comment Share on other sites More sharing options...
Ally V8 Posted October 1, 2008 Share Posted October 1, 2008 I happen to like EFI.Do we think this is a good or bad idea? Good. Quote Link to comment Share on other sites More sharing options...
paul stage1v8 Posted October 2, 2008 Share Posted October 2, 2008 depends on what you want the vehicle for, and what you have or are prepared to pay. The 3.9 and 3.5 efi systems are getting old now and if they give trouble seem to give lots of trouble, though my RRs have been fairly reliable. I intend to take my v8 to places where I wouldnt want to have to walk for help and so simple is better for me. But if it was only an occasional offroader and I could afford the time and trouble for setting up then megasquirt would be the choice. Quote Link to comment Share on other sites More sharing options...
paul stage1v8 Posted October 2, 2008 Share Posted October 2, 2008 depends on what you want the vehicle for, and what you have or are prepared to pay. The 3.9 and 3.5 efi systems are getting old now and if they give trouble seem to give lots of trouble, though my RRs have been fairly reliable. I intend to take my v8 to places where I wouldnt want to have to walk for help and so simple is better for me. But if it was only an occasional offroader and I could afford the time and trouble for setting up then megasquirt would be the choice. Quote Link to comment Share on other sites More sharing options...
ANTOINE Posted October 4, 2008 Share Posted October 4, 2008 like this on my 90 i have a 3,9L with 3,5L efi , with an exterior bosh fuel pomp 25 LIVRES on ebay sorry for my english Quote Link to comment Share on other sites More sharing options...
Mr Bean Posted October 5, 2008 Author Share Posted October 5, 2008 depends on what you want the vehicle for, and what you have or are prepared to pay. The 3.9 and 3.5 efi systems are getting old now and if they give trouble seem to give lots of trouble, though my RRs have been fairly reliable. I intend to take my v8 to places where I wouldnt want to have to walk for help and so simple is better for me. But if it was only an occasional offroader and I could afford the time and trouble for setting up then megasquirt would be the choice. With any modifications i plan to make i try to keep to keep as many standard parts as possible fpor when i am in remote places parts are easier to come by. So thats is why i plan on finding a V8 Disco with LPG as swap it all on to my 90 and replace the tired 3.5 with its carbs for something better. I wouldn't use megasquirt because if I'm in the middle of nowhere parts would be too hard to find. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 5, 2008 Share Posted October 5, 2008 I wouldn't use megasquirt because if I'm in the middle of nowhere parts would be too hard to find. So you'd use a 20 year old ECU that uses proprietary parts and has minimal support documentation rather than a modern one that uses standard parts available anywhere with circuit diagrams and parts lists & specs freely available? Happy travels! Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted October 5, 2008 Share Posted October 5, 2008 We have some experience of doing this in the opposite direction after a client blew up his 3.9 Efi and we bought a cheap carb 3.5 to replace it. The only real difficulty was replacing the high pressure fuel pump with one from a 110 V8 while keeping the fuel level sensor intact. With the Efi fuel system you need the high pressure pump and piping from the engine to the tank for the return line. Quote Link to comment Share on other sites More sharing options...
Mr Bean Posted October 7, 2008 Author Share Posted October 7, 2008 Would I need to fit an extra fuel line to the original tank as a return? Quote Link to comment Share on other sites More sharing options...
paul stage1v8 Posted October 7, 2008 Share Posted October 7, 2008 you should already have a return line anyway, carbs have them as well as EFI Quote Link to comment Share on other sites More sharing options...
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