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MG Midget and Sprite Technical - Maestro A+ engine in Midget

I thought I should move this to the technical section so here is progress so far.

I have modified an A series back-plate to fit by cutting a bigger crank hole to clear the aluminium ring in the adaptor that carries the crankshaft oil seal. The adaptor to VAG gearbox remains in place with the backplate bolted over it to make a sort of sandwich. The aluminium adaptor is pretty flat all over, hopefully flat enough to keep the backplate parallel to the engine rear face. Most of the bolt positions are sunk below the top surface of the adaptor so will need carefully sized spacers between the backplate and adaptor to spread the load and keep the backplate parallel.

I now need to find a 1275 flywheel and modify the bolt holes and maybe fashion a spacer behind it to give a bit more space between the back-plate and flywheel.
There is a hole in the end of the crankshaft which looks about 22 mm diameter so that will be the spigot bush problem sorted.

See image showing smooth case GB attached (I have a rib case stashed away, this was just handy to try). A couple more images will follow.

A couple of general questions before I go.

Will a 1275 flywheel fit inside a 1098 gearbox bell housing?

Is there a difference between the 1098 and 1275 gearboxes as regards the release bearing operating lever?

How necessary is the rear oil breather? (I will be using the single HIF44 on a Howley Racing inlet manifold. It has a timing cover oil breather as well as the rear one)




MG Moneypit

An image showing gearbox, backplate, adaptor and engine. Spacers will be needed between backplate and adaptor to mecanically couple the sandwich to the engine aand reduce stresses in the aluminium adaptor.


MG Moneypit

A 1275 flywheel will fit a 1098 gearbox.

I have a couple of flywheels.

I'm not sure about the clutch fork, will have to check. Although I've probably got a couple of 1275 forks, if you need one.

daveo138 AT yahoo co uk
Dave O'Neill2

An image showing where the starter motor will mount. The adaptor will need to be cut back here to seat the motor properly.

I now need to check the clearance between the backplate and face of the flywheel to see if I need a spacer between end of crank and flywheel. Measure for spigot bearing and fit. Fit clutch, trial fit ribcase gearbox and check out clutch lever throw.
MG Moneypit

If you put a spacer between the crank hub and the flywheel...you will need to reduce the starter mounting face by the same amount or the teeth on the starter and flywheel ring will be offsetand may just.barly connect

I would be very tempted to persue a concentric slave over a fork lever slave

Also...if your going to this much effort I dint think a ribby 4 speed is the way to go...I would really persue an altenitive...like the -ford type 9 or the BMW getreg Your going to have to shorten the propler shaft and get it rebalanced anyway...so might as well get somethinga little more bullet proof

Prop
Prop and the Blackhole Midget

Hi
Am intrigued
Why are you converting a maestro engine?
I have converted a marina engine recently and it sounds much simpler.
Tim
T Dafforn

I'm having problems contributing to this thread so 2013-12-05
MG Moneypit

Prop, the Maestro crank has a very thick flange where the flywheel bolts as the engine uses a conventional rear oilseal rather than the scroll type. This oilseal is built into the alloy backplate used to attach a VW Golf FWD gearbox (standard fit for the Maestro) and is about 1" thick hence the thicker crank flange. I have added a steel backplate to this so I can go back to an A series box. I need to ensure the flywheel face to steel backplate distance is ok to get the starter motor in the correct position and also to get the clutch operation correct.

Rob aka MG Moneypit
MG Moneypit

Tim, cost really. I bought a good running Maestro A+ engine with all ancillaries for 150. Recent eBay prices for midget engines are 350 to 500+ needing reconditioning. Maestro engines are cheap compared to even Marina engines because they dont fit in a midget (or so everyone says), but it looks like I will be able to make it fit for not a lot of money.

Rob aka MG Moneypit
MG Moneypit

Ok
Yes I was amazed at the price of pukka midget engines when I bought my wreck. Hence the marina engine. I had just completed a rebuild of a lotus twincam and thought the midget would be a cheap alternative. How wrong I was.
Got the marina engine for £150 which was an ok deal.
A friend up my road managed to get a new A+ engine from an ital, but then he used to work for BMC and new where the treasures were hidden.
Good luck with the install. Some more pictures would be good.
Cheers
Tim
T Dafforn

Image showing cutout in backplate. I didn't want to cut into the hole where the oilpump tophat goes but had to to make backplate lie flat. I can always weld a 4mm bar across if it needs strenghtening.




Rob aka MG Moneypit

Image of top part of backplate showing size of spacer needed. About 6 spacers are needed altogether.
Also I need to get elongated dowels to ensure alignment of backplate. Any ideas?


Rob aka MG Moneypit

Rear oil breather hiding behing backplate. Any ideas? Blank off? Cut out in backplate?


Rob aka MG Moneypit

Crank poking through backplate showing where oilseal fits.

Distance between backplate and end face of crank is 1cm. Anyone know what it should be on a 1275 midget?


Rob aka MG Moneypit

Rob its comming along... looking good

As to spacers what about some kind of recessed brass or stainless steel lipped bushing

Like a piolet bushing for a clutch in the back end hole of a crankshaft

You could even.thread the bushings inside dia and grade 8 bolt it from them other side (maybe)
Prop and the Blackhole Midget

Rob,

Welding the backplate may not be an option as I've thought they're some form of cast iron judging from the edge finish and I've seen a few cracked between the main holes. What did it cut like? If you have enough left of what you cut you could try a test weld on that and then hammer the welded sample to see how it stands up.
David Billington

Prop, whatever I do it needs to be as simple as possible due to lack of tools. For cutting I have a chop saw (radial arm saw) with a cuts everything blade so I can cut to length and with reasonable accuracy get a square end. No lathe or metal turning. So for the spacers I thought of thick wall alumin(i)um 15mm outside/ 8mm inside looks about the right diameter for 5/16 unf, cut to length.

The spigot bush I can probably get a needle roller bearing the right diameter off the shelf.

My biggest worry at the moment is the rear breather, whether to block off or use it somehow. I don't want to be contributing to the engine breather thread in 6 months time about posting 1200?

Rob aka MG Moneypit

What your doing looks really cool and I understand completely... people are asking 400/500 for a midget engine and there's no way you'd know if it even was in ok condition? So if an A+ Series could be made to fit - perfic!
What about the crank end though? is it like the metro and totally different, in which case which flywheel and clutch are you planning to use??
Very interesting project! Keep updating the thread please:) especially with the pictures.. is educational. I have a lot of interest the in a+series, I have never tinkered with them but am hoping to in the future.
S Miles

Rob,

Thats tough...in can assure you 100% that david is correct... these backplates are NOT weldable... I had a fine hairline crack in my plate about an inch long and got it back from the welder resembling a basket ball more then an engine backplate...these things dont like alot of high heat

As to the oil breather.. can you post a wider angle photo... I think that throwing us... well me, im just not able to grasp what your referancing... and the current photo is to close to turn on the imagination app.

Prop
Prop and the Blackhole Midget

Something interesting. When I picked up the engine the guy had the Maestro shell outside his workshop. We talked a bit and it turned out he wanted to do a bit of rallying with the Maestro. He had kept the VW gearbox originally bolted to the engine that I bought. I enquired about the gearbox, why he was keeping it and he showed me what he was doing. The gearbox was super clean and bolted to ............. An Audi 5 cylinder inline engine he had rebuilt. His intention was to put it into the Maestro and turbo charge it and have a bit of fun!!!!! Imagine that. A 5 cylinder turbo Maestro.
Rob aka MG Moneypit

OK, here is an image showing the alloy adaptor bolted to the engine. The red circle shows where the rear crankcase breather is. Contrast that with one of the ealier images showing the breather half covered by the A series backplate. A canister type oil seperator bolts to this and if I could remember where I put it I could show it attached. Doh!!!


Rob aka MG Moneypit

Hi all, bought a digital micrometer (£6.99 eBay special including post) and measured the hole in the end of the crank for the spigot bearing. It measured 21.92mm so presume it's 22mm. The A series input shaft measures 0.507 inches so presume it is 0.5 inch. So I need a Spigot needle roller bearing, anyone know a supplier?

What size is the spigot bearing for a late 1275 Midget?

Rob
Rob aka MG Moneypit

This thread was discussed between 03/12/2013 and 17/12/2013

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