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MG Midget and Sprite Technical - Begining the big re-assemble

Hi all,
I am FINALLY about to begin the re-assembly of my '70 midget..
Bought it 3 years ago as a basket case..
Spent 3 years welding (only get about an hour a week to work on it)..
The body (complete with speedwell monza on piece front) is now off being sprayed Rolls Royce magnolia..
Have collected together lots of new bits and reconditioned a load more..
So have a pile of questions..
1) anyone have any advice on sequence of reassembly (have done a lotus elan and spitfire before, and there were some bits where sequence was really essential. e.g. fit dashboard before fitting the back seats on a Lotus!)
2) anyone run a midget on the road without a windscreen?
3) my car had an alternator, which I think was an aftermarket change, anyone know where the wires should go?
4) have a Marina 1275 to go in, have it stripped down, the bores seem barely worn (bore gauge checked). Am going to check the bearings with a plastigauge. if good will fit new bearings. am also going to go for a slightly racier cam. Slight problem is that I hear the timing chain cover wont work in the midget (clash with breather). Was thinking about cutting the breather off and welding up the whole. Then using the redundant fuel pump opening for the breather. Will this work (have followed the breather thread with interest)..
thanks for any help
T Dafforn

As Haynes would say "just reverse the dismantling procedure" :-)

Good luck Tim. I can't wait until I am at the big rebuild stage. Such an exciting time where you can see big bits of progress being made.

Malcolm Le Chevalier

The other question I was going to ask, was, was there anything that people regretted doing in their rebuilds!
T Dafforn

I'm afraid I can answer any of your question, but I'll guarantee that this is the place for answers and I sure hope you'll be posting pictures as soon as it back from the paintshop?

Maybe you've got some pictures from before you started the disassembly? As teasers you know, of what's to come.

As for regretting stuff I'm not as far gone with my build as you're but I suppose some people has felt that they should have done some work more properly from the beginning, I for one felt the need to re-do some bits on my cars body.. lucky for me it wasn't panted yet. :)

Best of luck with the assembly!
Alexander Sorby Wigstrom

confirm the windscreen x quarter window fit before you get too far along (after a lot of body work, replacing floors, sills, and so on, this can trip you up, "at the very end" if you find that there isn't enough adjustment room in the fitting holes to get those two to line up)

confirm the door shut fit with the weatherstrip installed (ditto the above), there is nothing that lets down a restoration like a poor door fit that shows up, "at the very end", when it seems like "too late" to put right (maybe bending the flange will fix it, but sometimes a bit of cut and weld is called for)

luckily, there is very little that must be sequenced during assembly, other than to fit the wiper system before the dash, and to fit the drive shaft to the rear of the transmission before the transmission is fully pushed home into its hole, and to bleed the clutch before the slave is attached to the transmission, all three only because they are difficult to get to after assembly

the doors are the most difficult part to assemble, simply because there is so little space and the parts must be installed in a certain sequence. There is an article over at the MG Enthusiast website (US), in their library, with a step x step guide for doing it.

using the un-used fuel pump hole ought to work as a breather, in place of the timing cover (mini 1275's are sometimes modified this way)

anything to regret, you ask?
- Cutting corners early on, "because I think that this will just be a quick resto", only to find that the early work doesn't stand up to the later, "OK, as long as I am going this far I might as well also do..."
- finding out some crucial information right after you have completed a big job! Search the archives here, and on other websites (especially if they have a "library" of tech articles), because there is a wealth of great information out there, far beyond what the Haynes and Bentley have in them (but are still no substitute for those two important manuals))

good luck!
Norm Kerr

Not a bad idea to consider some sound proofing at the re-assembly stage. Stuff like damping pads inside the doors are well worth fitting whilst they are empty of all the fittings!

My main advice is fit each item permanently, never be tempted to only loosely fit or just assemble to "see how it looks", thinking you can go back and re-do it properly later. Its a waste of time and chances are you will never feel like going back to that bit!

If you can get a copy of that book "Restoring Sprites and Midget" by Grahame Bristow, it has an excellent and detailed sequence list in it for re-assembly.

Is the timing cover different on a Marina? 'Cause I have a mini timing cover with breather and tensioner behind it, no problems. It is the "special" flattened breather cannister, as sold by minispares. I also have a breather with cannister on the pump blanking plate.
Alex G Matla

For the Marina engine you need a Midget or Minor back, front plate and flywheel. Back plate + flywheel to mate to right gearbox and clutch and front to have the engine mounts.

You need to decide whether to keep the chain tensioner and Marina timing chain cover - which needs a few extra holes in the front plate. Or....lose the tensioner and use a Midget timing chain cover. This is the issue rather than breather. Note I retained the Midget duplex gears with the tensioner rather than simplex - it all fits though check clearance of the 2 screws below the crankshaft and of the baffles inside the timing chain cover if using the duplex setup.

You'll need machine flywheel or crank to match either other.

I used a Midget sump because I'd already brazed in an oil temp sender. The Marina sump should be OK if you get rid of the flat plate on the bottom.

Pictures of my 1380 on Marina Block:-

Specifically the Marina tensioner arrangement with the different timing chain cover and where the new holes are is quite clear. The tensioner uses the original holes for the smaller cover.
Dean Smith ('73 RWA)

I've got the back and front plate and flywheel.
In the process of getting crank out for machining to fit the flywheel.
was going to use a midget timing cover, but can't get one for toffee at the mo..
T Dafforn

With two rebuilds under your belt you are probably aware of the following but it may help.
When the body returns,clean out all the captive nuts, paint in these would be a right pain.
New nuts/bolts are not expensive and look much better on new paint, get yourself a good supply.
Agree with previous posts ref windscreen and doors, both can be troublesome.
Before fitting the windscreen wipers check the park position, if incorrect this would make a nice mess of the new paint.
Final comment-Copper slip, makes all the difference when you have to take it apart again.

Hi, I've been reading quite a lot about the breather setup on 1275 minis, and I reckon taking the breather from the fuel pump blank is superior to the timing cover. Ignoring any issue with oil sucking and concentrating on the real purpose for it, PCV, then I think connecting directly to the sump is a far better idea.

With the timing cover connection, the suction takes place through the small opening in the block face, and if the pressure in the sump is substantial, it must be easier to counter that directly by the fuel blank.

So I would say the fuel blank connection will work at least as well as the timing cover, and probably better. You probably need a baffle to stop oil throw from the cam, but I think the adapter you buy incorporates that anyway.

Lawrence Slater

What is the route of the connection between the tappet chest and the crankcase? Is there an open route of some sort there?

Yeah that's a point. I think I read somewhere that the follower tubes drain to a gallery, and that must connect to the crankcase. The older blocks used to breather from the front tappet cover.
Lawrence Slater

Yes, I presume it does breathe from the crankcase OK, but couldn't quite visualise how. I rather thought that the tappet chamber had a solid casting forming the floor, through which the tappets (cam followers) fitted in their machined guides. But perhaps there are drainage holes there. I know on the earlier cars with removable tappet chest covers, the tappets can be lifted out from there. Unlike the 1275 engines where they are put in from the bottom and are then trapped in place by the cam.

yup, here it is Guy.

8 tubes connected to a gallery.

Lawrence Slater

Ah yes, now I see the 8 tubes which are the tappet guides, and the two large drainage holes, These are what allows oil to drain down to the sump when you refill through the oil filler cap in the rocker cover> I thought it couldn't all drain through the little lubricating holes in the sides of the tappets!

I wonder why they are labelled as splash passages. I cannot see much oil getting accurately splashed upward through those passages! They are on the downwards side of the crank rotation anyway

These are unofficial pictures. A chap in the states, re-built his sprite, and because he couldn't find an official description of the lubrication system, he documented his own. Some of the descriptions may be not be strictly correct. Like the one for the small block opening to the timing cover, being described as a splash feed, when it seems it's primarily a pressure relief.

Follow this link for the full story. It's well worth a read, and has the full set of pictures.

Also follow the link at the bottom to his sprite home page. Good stuff there too.
Lawrence Slater

Thanks for those links Lawrence. Looks like a good bit of on-line reading matter to keep me from wandering too far from my laptop for a while!

Yep good stuff to keep you interested.

Follow this one to by the same chap. Steve Mass.
Lawrence Slater

Fit the main front to rear brake pipe before the gearbox/propshaft and driver's seat.
Dave O'Neill2

Before fitting the dash - wipers, crash pad, and probably windscreen - I installed my windscreen afterwards, but I think it would have been easier with the dash out. Someone will correct me if I'm wrong about the windscreen. As pointed out earlier you need to check the alignment of the windscreen with the quarter windows when you install it.

Probably obvious, but leave all the front panels off until the mechanicals and suspension are installed - not necessary, but much easier and less chance of damaging paint.

If you are fitting a LCB exhaust header without a break in the vertical pipes, it will be much easier (with some headers it is actually necessary) to put it in place before the engine goes into the bay, and you will most likely also need to cut the back of the hole the exhaust goes through for some additional clearance if it hasn't been done already.

Can't think of anything else that hasn't been mentioned above, but if I do I will add it.
Andrew F

I'm in the same position as you. Just started to reinstall everything onto a newly painted she'll. It's the best part. I'm starting with the doors as I love doing them! I'll do the windscreen then before starting on the rear & front suspension, rack, steering column etc etc. the brake pipe will definately be going in early doors. Ill also ve getting tge main loom insiru too. Engine will be left until a bit later. Soooo much to do. Andrews advice re leaving wings and nose cone off till the end is sound advice.
Neil K

Will sort out some photos.
Anyone know where you can get a fuel pump blanking plate with breather.
T Dafforn

This what you're looking for?
Alexander Sorby Wigstrom

That's the adapter, I'm still looking for the breather can to bolt to it. Looks like it might have to be a home made job.
Lawrence Slater

the breather that you would use for the fuel pump hole comes from the bell housing end of a mini engine, mini mania also sells them (used) for very reasonable cost, give them a call

oops, sorry, forgot that you're over in the UK, OK, call mini spares instead (they both sell the same parts, and use the same part numbers, and one is on this side and one's on the other side of the Atlantic)

Norm Kerr

Hi Norm, yup looked at them, they sit at the wrong angle, and the flange is at vertical when whst's needed is a horizontal one.
Lawrence Slater

Lawrence I thought that adapter was threaded so you could connect a tube from it to a vented oil catch tank since the engines bound to sometimes push a small amount of oil out that breather?
Alexander Sorby Wigstrom

You may well be right Alexander, I haven't seen one close up. I'm told you also need the adapter to act as a baffle, to prevent the fast spinning cam throwing oil into the tube.

I think I'm going to end up making one at this rate.
Lawrence Slater


There were two different shapes of breathers that were bolted on to A series engines used transversely in the various FWD cars over the years. You might need to poke around their website a bit to find them, or give them a call.

Or, like Alexander indicated, you can make your own breather and connect it to the mini spares adapter (a separate catch tank doing essentially what the breather was supposed to do, condense / collect oil and let it drain back into the sump).

Norm Kerr

This thread was discussed between 01/03/2012 and 02/03/2012

MG Midget and Sprite Technical index

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