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Converting a carb'd mini to Tbi
Here's the recipe to create an electronic injectionized mini. You require:
1 unsuspecting carby mini
1 preferable complete but totalled Tbi mini
1 spare MG-Metro (or other) cam
Lots of patience
Some tech. knowledge (like: to fasten; turn clockwise ;-)
I think an ordinary (unleaded) 1275 engine will do fine as well
I started by taking the Tbi apart (I bought it as a (totally bent) runner). I'd done some research, and found out the only difference in engine between standard Tbi and Cooper Tbi was a higher CR on the Cooper (probably by means of shorter block and different pistons (less deep dish), because the heads are the same), and a different computer. Since my goal was a little more than the standard 54 Hp, I had the head skimmed to get the CR a little over the Cooper's (some 10.3 vs 10.1 (9.4 is standard Tbi).
It's also possible to go to a hairier cam, since the MEMS-ECU (Modular Engine Management System Electronic Control Unit) can adapt to "new" circumstances. I opted for a MG-Metro cam;
because I read in Minimag that 255 deg is the fastest cam that still makes for a "civil" engine (I do a lot of village/city driving)
because it sat jobless on a shelf in the garage. I didn't bother with changing the followers since it was a used cam (we'll see if this was a good plan;-), and I didn't feel like separating the block and 'box.
First I removed the head and send it to the machine shop to be skimmed. Then I tilted the unit on the bellhousing (using some wooden blocks for support), and turned the cam a few times before lifting it out vertically. This made sure the followers were way up in their bores.
Then I lowered the 'new' cam in the same way (on A+ units there's no loose spiders, or other creepy crawlies to take into account:-) It was precisely on time, but DV writes that this cam works best if timed in at 106-107 deg instead of 110, so this I did. I put the engine together and gave it a nice fresh coat of red paint. I wanted to ditch the cat, because I didn't feel like buying a new RC40 rear section when I had a 1 year old Maniflow LCB/RC40 system already. This was one of the most complex things: the original Lambda sond had to be retained, but in my LCB there was no hole for one to fit, on top of that for some reason the thread on the sond is neither metric nor UNF (but Bosch' own I guess).
Luckily with the Tbi came a section of manifold (from the size it looked like a Range Rover V8's!), from which the correct nut (still holding a sond), was ground out (thanks Johnmar) and welded to my LCB. Then: horror! When I offered up the LCB to the engine (still not in car), the sond fouled the fuel pump blanking plate:-( Had to do that all over again. It also turned out the intake manifold's water cooling pipe fouled the center branch (how do Maniflow solve this?). You have to use it because the temp. sensor is in the throttle body now. I had to heat the pipe up really well and had to bend it totally to make it clear the branch (and then foul the bulkhead crossmember, so I did that three times:-). In the end it split but I was able to braze it. In retrospect it could have been done with a little less twisting I think.
I also applied some DV tricks to the butterfly and spindle (slimming spindle down, knife-edging butterfly and removing butterfly screws' split ends) After all that I turned to the poor old Parklane, who was suspecting something by now, since his engine had been removed and dropped into the Mayfair to have at least one car on the road.
I removed the interior (just for easy acces) including wooden dash and switchpanel (to be replaced by 5 switch type), steering column and pedalbox, heater, fuel tank, complete clutch system, wiring loom except the rear section and master brake cylinder (+ front brake pipes, which needed replacing anyway). Then came the process of planning fuel line routes, putting in the new (2 section) loom in the engine bay (I used some of the rear section too, but that's later). I bought 6 metres of rubber fuel line and laid it out; it was only just enough, since there's a return line as well. It now goes through the 'gap' between rear seat upright and rear wing panel, then through a drilled hole in the LH companion box, along the floor, through holes in the crossmember, upward along the bulkhead and it comes through the bulkhead a bit to the right of the clutch master cyl.,from where the original pipes lead to the injector housing.
Nearly the same route is followed by the rear section of the Tbi's wiring loom, which is used only for the in-tank-fuel pump and the screen washer bottle, which now sits in the LH companion box (keeping it a bit warmer during winter, but it's really noisy!). Then I had to install the new servo'd brake system, which was fairly straightforward but involves a new pedalbox and a heavy beam across the width of the car to operate the joined pump/servo (sitting RH on the crossmember, so this doesn't apply to RH cars). I used the Tbi's pipes to connect it all (the location of the brake limiter is slightly different, so no straight swap (later found out they're *not* compulsory in NL, but probably wise to use anyway). Finally time to fit the engine, which was not anymore difficult than usual.
Fitting all the wires and hooking up all sensors took me a full day. Then came the big moment; I turned the key to II, the ECU clicked and the fuel pump span. I turned the key to III and it cranked, but that was all:-( No fuel from the injector and no spark. At first I was affraid I had made a bad connection and blown the ECU, but that didn't seem the case, because when I took the key out, it made another clicking noise (which Johnmar told me it was supposed to do). So I tore out the injector, thinking it might be blocked, but that wasn't it. In the end I phoned the dealer. He told me to check if the flywheel TDC sensor received signals. It then started to dawn on me that I could have fitted the wrong flywheel. I ran to the garage and in the corner it sat, waving it's reluctor ring at me;-).
After I fitted it the next day the engine burst into life on the third stroke:-). To the delight of various neighbours I took it around the block without the RC40 to celebrate. I was immediately punished when my LH rear wheel overtook me:-}. I was only doing 10 Mph or so, so apart from a damaged (but easely repairable) rear wheelarch no harm was done. Next on the list was the heater. New minis use bigger diam. pipes and they sit on the other side of the heater. Another thing was that the new brake system covered up all the holes in the crossmember. In the end I removed the bulkhead blanking plate and drilled two holes in that, just large enough to put a hose connector through. The only problem now is that the heater mounting points on the bulkhead seem to be useless, because the brake-bar is in the way.
I'm still looking for a better solution than the current electricity wire:-) While I had the hole thing apart I fitted the new woodgrain Pioneer 5400 radio, which looks great; it matches the dash grain very well and it sounds brilliant:-). The car is a lot quieter now (when stereo off:-), because I also fitted the more extensive Tbi sound deadening material. I've now driven it for some 70 miles and the ECU is adjusting quite well. At first it would stall when I took my foot off the loud pedal, but it now happily idles at some 850 revs. The plugs have a healthy color and it pulls like a train from 2000 RPM (probably due to the MG cam). At 60 Mph there still seems to be enough power left, but I'll try that once it's all a bit settled. Braking is great too; I'll never go back to non-servo now:- I'll try and persuade Johnmar to see which one's faster. It also apears to be economic, because in 70 miles, the fuel gauge is now just below the top mark:-)
In all I think it was a succesful operation, but it requires plenty of time (I took my time: 2 months, in odd hours and a number of full days) to do properly (and you still will fit the wrong flywheel or worse:-( I thank Johnmar Mulder for his h*lp and lending me Manuel's latest edition (which btw, apart from the new electronic section, is a real step in the wrong direction (no gearbox section, no timing charts (for older engines), not even how to remove the front subframe mountings!, and a lot of "when this problem occurs, refer to your dealer"), so get an old one while you can!).
Although it was a bit long I hope you enjoyed the read and are not too discouraged to have a go as well:-)
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