|The 'other' way
to do it.
There are a couple of companies supplying the bits to do a Prima conversion for the land rover, and if you're going down the buying bits route I would reccomend getting your gubbins from Richard at www.integerspin.co.uk. Now if you dont fancy buying stuff, have some ability with a welder, have time on your hands and like to get involved in stupid projects then read on....
Richard's, and other's, adapters replace the montego gearbox adapter at the back of the engine giving the correct offset for the landy gear box, provide a mount for the starter and a hole for the crank into which an oil seal sits. The offset (distance from engine block to bellhousing bolt face) varies in the different adapters from something like 58 to 61mm, we calculated i believe to 58, and there are adapters at 61, whatever, its arbitrary as we shall see, but handy to keep that figure in your head.
Now, interestingly enough, while the montego adapter is a clever bit of machined alloy, the adapter as fitted to the Sherpa van running the normally aspirated prima is this:
Thats right, flat steel plate thats 10mm thick, with all our mounts, oil seal, starter hole, all ready for us, that takes 10mm off our offset, so we now need to make up the extra 48 - 51mm. We chose to use 50mm, as its a nice round number and also steel stock is available in this size.
So, to create the remaining stand off we could be posh and use some bar stock which we drilled and tapped for studs, or, we could just be lazy and weld a bunch of M10 bolts to the adapter, guess which we did? I know some might say that its a cheap and nasty approach, but then hey, thats the way all of this started! So the tricky bit is getting the bolts into the right place, 2 choices, measure very very carefully using some kind of compass hanging out of the crank to get a good circle for the bellhousing bolts. Or, get an old landy bellhousing with an input shaft attached, stick M10 bolts in each hole (with double nuts at 50mm, and wrapped in tape to center them), fit the pilot bearing into the crank, and offer the two up together to get the bolt circle. If you do this you need to up end an engine (we had a 'spare' just for mocking up on) because otherwise there is far too much play to get in the right place. Check the input shaft spins absolutely vertically, a good way is to shine a light past it and use its shadow on a notepad to check for runoff, keep adjusting the postition till its centered. Then tack weld each bolt in place, and you'll end up with this:
Its entirely up to you how safely you get there, we employed Zim Health and Safety methodologies throughout the project as Rob_M demonstrates:
Cool, so now to fill in the gap and make it strong, grab some 50mm by 2mm or 3mm (i forget which we used, might have been 3) strip steel and get wrapping:
Start with the stud just below the starter hole, go round tack welding as you go, then finish near the other side of the starter hole. Its important that the strip is well positioned here, too far out and you foul the starter mount hole, to far in and you foul the flywheel, ours have about 3 or 4 mm clearance with the flywheel. Once its all in place, weld it up, but as you do, offer it to the bellhousing as the welding pulls it all inwards, so Land Rover Special Tool #1 is needed occasionally. Dont forget to weld those pairs of nuts (ooh sir!) to the band. Make some nice curvy bits for the starter, and chop off the power steering mounts that stick out, as they foul in the landy (we found out the hard way), fill any gaps and drill a drain hole in the base of it:
Note the adapter 'stand', absolutely critical to get one of these! Tidy up any errant welds with Land Rover Special Tool #2, especially those on the starter cover that will go under the bellhousing. Note how Rob_M is again employing a sensible attitude towards protective gear when using dangerous power tools:
And thats it, a lick of engine enamel and you have an adapter! (or two!) (note the Power steering mount is still there, we had yet to realise our folly):
Engine mounts are actually pretty easy, if a bit fiddly. The prima engine is shorter than the 2.25 and handily, 10mm narrower, so 2x5mm plates drilled for the prima mounts and bolted on the side of the engine can be tack welded to the old mounts with the engine up in place on its shiny new adapter, before removing the old engine make a note of the position of the crank relative to the chassis rails, and suspend the new engine in this position.
You'll have to tweak the oil feed to the turbo out of the way, and weld a stud on the RH mount for the alternator adjuster, you can always download and use Richards plans for these as well, but we were lazy ;-) We did use his alternator mount plans though (cheers dude!) as we couldnt find anyway of suitably cheating!
So thats how you physically get the engine in place, when I get some time I might put some other info up about exhaust/cooling/etc issues that came up and were solved during the conversion, there are a lot of ways of doing this conversion, and the choices, at the end of the day, are yours.
There are also now some addtional pics in my gallery, linked below, which were just photos taken during the conversion, they may be usefull...