The correct battery for a Murena (and probably a Bagheera) is an '049' battery. This code denotes the physical
dimensions, the types and positions of the terminals, the clamping arrangements, and possibly the power level.
However, it is not very common judging by the number of stockists that keep it 'on the shelf'. The '048' in
fact tends to be much more common and more likely stocked. The only difference between the 048 and 049 is
that the positive and negative terminals are reversed, so it will not fit without some modifications.
If you are prepared to do these modifications, you will have access to a few more batteries, and there is a
common one that is better, more powerful yet fits nicely. The original battery was around 265 CCA whilst the
better one is 380 CCA, so you have a better capacity within the same physical size case. It is the battery for a
Mazda MX5 which I think you will agree is common enough for there to be batteries generally stocked. Since
this is like the 048, you will have to make up, or have made, a slightly longer earth lead and replace the
original. Then simply shorten the positive lead and fit the MX5 battery. Whilst shortening the positive lead you
can replace that terminal for the lead to the circuit board and get rid of one potential problem area too.
You will also need to change the original clamping arrangement (assuming it is still there and working - which
is not often in my experience!). The original battery had ridges along the bottom edge of the casing for the
brackets to clamp on. The MX5 battery does not have these ridges so you will need to devise another method to
clamp it down. I suggest an 'L' shaped strip along the top edge and two hooked rods to clamp it, like you see
on some other cars. You can often buy these parts as a kit from parts suppliers. Batteries should always be
clamped as it reduces the wear from a heavy battery moving around and helps improve their life.
First of all, if you examine the installation, the engine is mounted, not on the block like most cars, but on the
sump and the gearbox. Therefore you can't simply drop the sump off without making alternative arrangements to
suspend the engine! Since the long (RH) driveshaft runs in a bearing held in a non-removable sump casting, it
has to be slid out which involves removing the RH trailing arm. If you decided to do the job, leaving the engine
in and suspending it, before you drop the sump, you should remove the oil level sensor otherwise it is likely to
get damaged.
However, I have usually found that not only is the sump gasket leaking, but the timing case seal is often leaking
too. Taking off the lower timing case involves removing the water pump and crankshaft pulley, and the sump
mounting normally gets it the way of the latter, but as you are removing the sump, you might think this is now
the time to do it. But removing the water pump means tilting the engine away from the RH inner wing, which
is more difficult when you have the engine suspended. You have to release the gearbox mounting and lower
that end, and what you now have suspended is no longer just the engine, but the complete powertrain! And you
must remove the original air box on a Prep 142 or S, if still fitted, otherwise it will foul the fuel tank. Finally,
removing the crankshaft pulley and the lower timing case whilst the engine is temporarily suspended in the
engine bay, is not particularly easy either. Also, while you are fixing oil leaks from the engine, you need to
check and make sure it is not leaking from the rear main bearing seal behind the flywheel. This is not a lip
type seal as with more modern engines, but a cord type seal set into a rear block housing cap; with a reverse
scroll and thrower on the crankshaft to deflect oil away from it. (This is similar to old BMC engines if you
have ever worked on them.) If you do have an excess leak at this point, then you have to remove the
crankshaft to fit new cord seal halves, so you can see the job becomes one where removing the engine is
definitely the easier option!
This is why I normally recommend you take the complete unit out. Yes, it becomes an even bigger job, but not
by much, and you will be able to work on it much more easily, and you will be able to see ALL the things
that need doing, and do them in one complete job.
The sump gasket is special on the Murena and MUST have metal spacers in the gasket. Think about it. Since
the engine is mounted on the sump not the block, the engine must be rigid with the sump. Especially since
the gasket is cork. If you only have a soft gasket (whatever type) it will soon get damaged by the power unit
movement, and it will be leaking again in no time. So don't try to use the 180/2 litre/Tagora sump gasket.
The bolts are torqued up on the metal spacers, and the gasket forms the seal but does not take the load. This is
why the sump gasket is special to our car and costs a little more. When the original supply of Matra sump
gaskets ran out, I had some more made up by Cooper-Payne but without the spacers - just the holes to take the
spacers. You simply transfer them across from the old gasket to the new one. This is why my gaskets cost much
less than others. Mine cost around 35 Euro plus post and packing, where I think you will find others cost possibly
twice as much or more. Please check them out. The choice is yours.
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Yes, you can, but there are a number of modifications you will need to do. The most expensive alteration will
be to the cylinder head if you wish to use the Tagora head. The Murena head has extra material to take the
engine reaction bar mounting bracket which is not usually present on Tagora heads (but may be there on late
ones). You will need to have the head modified to the same as the Murena one. A machine shop will have to
build up the alloy and then machine it to shape. It can be done, and if you take along the old Murena head
as a pattern, there should be no problem.
The camshaft is a different profile, the inlet manifold and carburettor, and the exhaust manifold, are all different
but I assume you will be using the original parts, so they should present no problem. If you do use another cam,
or have one modified, remember you MUST use new followers with a new or modified cam, or keep the
original followers and shafts IN THE SAME PLACES if you swop a cam from another engine. If you don't,
expect excessive cam system wear! In fact, with all engine strip and rebuilds you should keep all parts in the
same places unless being renewed. The distributor, water pump, crankshaft pulley, and sump, are also different
of course, so the originals should to be used. There will also be other items like the engine mountings, dipstick
tube, and various brackets where you will obviously use the Murena ones not the Tagora ones.
The flywheel needs a cut in it to mark the TDC point, so if you use the Tagora one, you need to modify it.
Since flywheels can be 5 or 7 hole you cannot necessarily change them but if you did, and because you are
changing the crank pulley, you should have the engine re-balanced. You could have the flywheel lightened slightly
at the same time. There are also two modifications you need to make to the block. If you check carefully you
will see that two (if I remember right) of the bolts holding the engine to transmission, go the opposite way. So
the thread is in the bellhousing and the block must have clearance holes. A Tagora block will have all holes
threaded, so you need to drill them out. Finally, there is a casting lug that sticks out and will foul the RH drive
shaft coupling. You must cut this off first.
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