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MG Midget and Sprite Technical - Engine Build

For those of you not on Facespace, but still like an update on goings on, I have just had a long weekend so was able to make some great progress on my engine re-build.

A few piccies for your amusement and delectation...

Pic 1 and 2, building up the crank. All the rotating mass was balanced up last week. Lightweight H-section rods, ARP bolts.

Malc.





Malcolm

Pic 3. Bodge-a-baffle sump and altered oil pick up pipe. I was constantly losing oil pressure under heavy braking (the pickup sucks from the back corner of the sump...) Baffles will hopefully control oil slops a bit more, and the pickup is now lower in the sump and sucks from just behing the transverse baffle.

Pic 4. Short engine all done, about to double check cam timing. New trigger wheel on the front pulley.






Malcolm

Gearbox on and a lick of silver paint.


Malcolm

Back in the car, head on, test fitting new manifold and various bits of plumbing.





Malcolm

Wow! Great stuff Malcolm.

(Wait till Nigel spots the Triumph manual hahaha)!
Greybeard

Yes, great work Malcolm. I also couldn't help noticing the Haynes!
Bill Bretherton

I do have a midget workshop manual too, but when I first did an engine re-build I only had that Spitty manual. I earmarked all the useful pages like torque specs, tightening sequences, end floats etc. so since then it became my go to for engine stuff as I know where all the information is.

Malc.
Malcolm

Well done Malcolm, an inspiration to us all
R.A Davis

Nothing wrong with a Haynes, got to have something to rest your mug of tea on, and they insulate the bottom of the mug from the cold concrete to keep your tea warmer at the bottom.
Nigel Atkins

Just stick a K series or 2.0 Zetec in there and have done with it......
Oggers

And end up with something the same as everyone else? Nah, no thanks. Where's the fun in that?! :-)
Malcolm

I find my Haynes particularly unhelpful for the 1500 engine. I have downloaded a Herald/Spitfire manual from t'internet, which has proved most useful.
Dave O'Neill 2

Why does everyone else's spotlessly clean engine work always look so much more spotless than my spotlessly clean work?

Nice job Malc!

When are you fitting an overdrive gearbox in it?
GuyW

Thi9s is where I found the w'shop manual, if anyone else is interested.

http://vitessesteve.co.uk/Servicemanuals

There are also some Lucas manuals to be found there.
Dave O'Neill 2

Guy, if I were to go back ten years to when I was doing the bodywork I would have make provision for a different 'box. But now I loath to go slicing up the body after so much effort to make it solid. I fitted a 3.55 diff this winter instead.

On the topic off cleanliness, a picture paints 1000 lies ;-)
Malcolm

I really liked my overdrive conversion when I had my 1500. So much more engaging to drive, which is appropriate for a gearbox!

The body tub modification is pretty minimal too - it's just that cross member to cut and replace with effectively a small removable sub-frame. Oh, and spread the tranny tunnel a bit with a scissor jack but that doesn't involve any cutting or welding.
GuyW

Good stuff Malc.
I must say though, I'm not a big fan of your baffles, nowhere for oil transfer from section to section unless the running oil level is above the height of the transverse baffle--which I doubt
Apart from that, looks good
What rods are they--Maxpeeding-?---I'd be interested to know what bigend bearings you used with them and how much crush you got and did you do the cap bolts up to a tension or go the stretch method-----just interested in the combo.
Cheers
willy
William Revit

Baffling sumps can be fun ;), some years ago when working for a racing company I got asked to stop off at Prodrive in Banbury to pick up some sump baffle flaps as used by BMW on some M cars IIRC, I had a wander around the workshops prepping some of the WRC cars before finding the parts place. The flaps were like these https://www.ebay.co.uk/itm/ANTI-SURGE-SUMP-FLAP-OIL-PAN-FUEL-TANK-FLAP-VITON-COMPATIBLE-COSWORTH-BMW/283947658506 , have a look at the images to get an idea of their use.
David Billington

Hi Willy,

The baffles aren't welded all the way round and are a fairly rough fit, so there are gaps around the bottom and the sides for oil to flow through. By design of course! ;-)

Yes, they are the Maxpeeding rods and they have worked well for 3 years already. They are very tight on a +20 overbore, a +40 would be better. Also the oil pump needs a bit grinding off.

I use the standard big end bearings from King. I can't remember crush figures, I'm sure I measured them last time, but that was three years ago.

I just torqued the cap bolts up to recommended value with everything covered in ARP lube. No fancy stretch method here!

Malc.
Malcolm

I guess it depends what you want. Personally I think you are trying to make a bit of silk purse from a sow's ear. If you are going to that degree of trouble and expect something with a good deal more poke, then I wouldn't start with a 1500 engine.

However, each to his own for sure.
Oggers

All good Malc. Thanks for the info--I hope your baffles work out ok for you
Cheers
willy
William Revit

My wife had a 1500 years ago and I got a ‘remanufactured’ engine as oil pressure was not very good, it was obviously not a Midget lump, likely a Spitfire or Dolly - although sold as a Midget one .
I remember having to change the sump and oil pump - can’t find my notes now but thought the Midget had the vertical pump - would that not sort the surging as it is more central pick up ?
Hers was a very late car and the engine I replaced was very original as the car was only a few years old.
richard b

Hi Richard, in the long and dubious 16 owner history of my car, the engine ended up being transplanted for a Spitfire model with the angled pickup (I forget the engine code, but it was for sure a Spitty one).

I did notice in my Midget manual the drawing showed a vertical type - which would tie up with your comments.

I considered swapping, but decided to work with what I had as I am (relatively) time rich but money poor. I shall suck it and see if it works. If not, it isn't the end of the world to drop the sump and try something different, it's not an engine out job fortunatly.

Malc.
Malcolm

Found this - not the clearest of documents.

HTH

Richard B.



richard b

Seems TKC1975 is now superceded Brown and Gammons note GLP145 as updated part no.


https://www.ukmgparts.com/product/unknown-any-car-part-unknown/use-glp145-tkc1975
richard b

Wow, thanks Richard, interesting, every day's a school day.

I wonder why was it was not considered a problem on the Spitfire?
Malcolm

I've only ever done the oil pump swap once years ago and memory is getting dim ! but the sump is reduced on the Midget at the front to clear the chassis - I've not checked for varying sump capacity either.

The Midget Haynes manual 'Exploded' arrangement pic of the engine is incorrect for Midget (a Spit or Dolly is shown as sump and pump are incorrect) Fig 18.1A shows the pump facing forwards, is this possible ? I don't know, is bolt set out/oil gallery routing etc O.K. to allow this orientation ?

There are quite a few comments on the web regarding loss of pressure in 1500 Midgets with Spit pumps.

R.
richard b

Looking at your very clean engine I guess its not possible to line it all up.

So I don't know why either !

R.
richard b

I've just rebuilt my 1500 engine which had a straight pump, I had an angled pump I bought years ago and was a bit unsure about using it. I got some new pistons from a company that rebuilds these engines and asked which pump I should fit, they said the angled pump. I did think about cutting and welding it so the pickup was central but in the end went with the angled version. As Malcolm said it's easy enough to swap these if I have an issue. Bob
R.A Davis

Malc

I am enjoying hearing about your innovation and ingenuity in this project. All power to your elbow - skill and clever brains, rather than unlimited funds can produce surprising and interesting results.

I am surprised no-one has yet suggested squeezing in a Dolomite Sprint 16 valve engine or perhaps the lent over Triumph derived SAAB engine (FWD IIRC but you like a challenge!)

Guess you have heard of the Fright? (6 cylinder Jag engined Sprite) as well as someone who was building a Ford Cosworth powered Sebring Sprite replica?

This also reminds me of all the BMC/BLMC/BL ‘what might have beens’ from the Morris Minor being designed for a flat four engine (hence wide engine bay - anyone put a Subaru engine in one yet, have been some great Rover V8 conversions - google ‘Nick Mann V8 Morris Minor hillclimb’ as well as Fiat twin cams) as well as the few prototype Austin Ants (small 4x4) and the other ADO (Austin Drawing Office) numbers that never reached production. See: http://www.austinmemories.com/styled-95/index.html & https://www.aronline.co.uk/ Noting when Standard Triumph joined the Austin Morris [BMC) and Leyland party. Have not touched on Triumph design and works comps folk either.

All adds to the joy of life.

Cheers
Mike
M Wood

Dolomite Sprint in a Midget? Too slanty for the narrow engine bay. I'm surprised no-one did it to an MGB, much better idea.
Rob
MG Moneypit

I did ponder the Saab/Dolly Sprint engine at one point, as it will mate to the Triumph box IIRC.

Or a 2 litre GT6 engine, as something with more than 4 cylinders would be nice... The flat 6 from a Honda Goldwing bike would be interesting...

Or turbo... ha ha! 150 hp once, then KABOOOOM!!!

With the fully programmable ECU etc. I could do anything really... It's just a matter of packaging. But packaging tends to require chopping and welding, which as I said about the gearbox, I can't really be bothered with right now.

Malc.

Malcolm

IIRC Brian Wheeler had a frogeye with a Dolly Sprint engine in it, I've seen it on a couple of occasions at the Wroughton autotest run by the late John Mead, it required a rather large bonnet bulge which was not attractive IMO.
David Billington

I say this without any expertise but don't you reach a point where an engine is too powerful for the limited suspension and general handling of a Spridget? You must surely get into, say, Lotus Elan territory where, although more expensive, would handle the power much better.
Bill Bretherton

Erm... yes and no... there are suspension and brake upgrades that can then be done to "control" the extra power. It depends on how far you want to go and at what point you draw the line of it not being a Midget anymore.

Jonothan Heap, for example, built a 200 hp Ford Zetec powered Midget. A great project, great bit of engineering and outwardly it looks like a Midget... but there isn't actually much Midget left!

According to Motorsport UK regulations my car is still classed as an unmodified "road going production" model, as it is still the original engine block, head, gearbox, suspension system, brakes etc. but everything is upgraded within the scope of those regulations.

Malc.
Malcolm

David

Martin Ingall’s excellent Sebring Sprite website mentions a Brian Wheeler (of Wheeler and Davies Frogeye Sprite new steel shells) built Sebring Sprite Couoe replica with a Dollie Sprint engine and modified Sebring Sprite bonnet, see replica number 4, GB vehicle registration (licence plate) number 773 RW in the list at: http://www.sebringsprite.com/list_of_sebring_replicas.html and an article with pictures:
http://www.sebringsprite.com/pdf-files/MossReport.pdf

Wonder where it is now?

Cheers
Mike
M Wood

Mike,

A photo here of 773 RW http://www.sebringsprite.com/images/SstoneCl13-007L.jpg , definitely not the car I saw which had frogeyes so maybe it got reworked. The one in the link looks much nicer IMO.
David Billington

My midget hillclimber was B series powered bored and stroked and around 200hp
Suspension ,although modified was basically midget, leaf spring rear and std bottom arms on the front
There's a lot of story out there that you need this and you need that but spring choice has the biggest influence on ultimate grip level
If you think seriously about it and get it right the front wheel only moves around an inch and a half in compression and around 2 1/2" for the rear
With this limited amount of travel the wheel doesn't really care what's holding it up ,as long as it holds it in place
With correctly set up leaf springs a midget would take any power you put through it and have better traction to boot compared to all these whiz bang offerings

willy

Bill--I'd much prefer a midget suspension compared to a fragile Triumph Herald based elan
William Revit

Willy

That’s a very interesting reflection on MG Midget suspension based on your own build and racing. I guess you used an MGB gearbox, but what rear axle did you use? Did you move the MGB engine back a bit?

Malc - what are current and new products from ‘Chevalier Classics’?

David - 773 RW is still on the road according to DVLA online vehicle search, engine listed 948cc (thought a Dolly Sprint lump was a bit bigger!)

Cheers
Mike
M Wood

Here is an interesting projected Mini replacement started in 1967 - Project 9x - that never hit production - the engine is a fascinating take on an A Series replacement as well as the car itself: https://www.aronline.co.uk/concepts-and-prototypes/concepts-bmc-9x/

I do have a soft spot for some of the design ideas used by BMC for prototypes, new cars, and components in house and by consultants such as DHMC, Weslake and Downton as well as in the works competitions dept, Morris Engines, including right up to the design of the K Series engine in Rover days.

Cheers
Mike
M Wood

Mike, thanks for that link to the 9X project. Really interesting, but awful looking!

I recall sometime in the early '69s a friend's dad was working on a plastic bodied version of the original mini shell. With the separate front and rear subframe design they struggled to make it rigid enough and there were clearly issues over methods of accident repair so the project was scrapped.
GuyW

Bill

It's a fair point. My 2.0 Zetec Midget does handle extremely well, but it is polybushed and has gas dampers all round, has anti tramp and roll cage fitted, and modified discs/brakes up front. Nothing too major I feel, though I always think a Panhard rod may improve things further. Bodywork is lighter than stock - GRP bonnet, no bumpers etc, and I cannot think the engine and type 9 box is much heavier than the original 1275 engine and box.

Handling is also making the best of what you have. My set up is finely honed, and even the mk3 when camber, tracking, dampers etc were optimised, the handling was very good indeed without the need for fancy bits and bobs. The organic blob behind the steering wheel also has a part to play of course.

The one thing it does do when driving in a spirited fashion is rub the tyre wall against the (square) inner wheel arch. You can smell it sometimes! I've pulled the arch out a little, but there is only so far you can go. The car itself never seems about to let go though.

Is it still a Midget? Well to a purist absolutely not, and for me, since the engine, box and bonnet are completely different to original, probably not either but then I am not looking for originality.



Oggers

Some really interesting diversions here. It makes me yearn a little to do a Sebring Sprite or similar build... I think they look superb.

Mike, still do rear wheel bearing kits and shock kits by request. Current project is a front shock triangulation kit (see my trunnion bolt thread - I will be finalising the order for the ~4.25" long trunnion bolts this afternoon). It was just going to be for my own use, but then I had to bump up some orders to make minimum quantities and meet bulk buy thresholds etc. so I will have a few sets spare. It is a bit of a punt, I hope I can find buyers or I am a bit out of pocket. But the price should be attractive @ half that of a Peter May kit.

But same old story, no time or inclination to develop CC further than the current level.

Malc.
Malcolm

Its an interesting thought but there must be few if any other "production" cars with a greater range of owner derived upgrades and modifications than the Spridget range. I don't include the specialist after market bolt-on items developed by tuning companies, but am talking about useable upgrades and alterations developed in garages and sheds that most half-capable DIYers can adopt. It would make quite a catalogue!
GuyW

Guy

Up here, you'll find mk1 and mk2 Escorts have a plethora of upgrades and modifications as you describe.
Oggers

Yes, I did wonder about those, and minis. But many of their upgrades are engine related. I think that Spridgets seem to have lots of body tub, suspension and other upgrades as well. I do think that Rallying, before the big manufacturers came in with massive budgets, spawned a lot of owner-derived modifications and the early escorts were certainly in that category.
GuyW

Many of the Escorts do indeed still rally. As such, not only engine mods for sure. Beautiful (orange!) mk2 just down the road, a Mexico at my local garage, and a dozen or so turned up at the last car rally we had - considerable given we are in the middle of nowhere really.
Oggers

Willy, Oggers
Interesting. Despite my liking for Spridgets I'd always assumed an Elan had far more sophisticated suspension and handling. I don't like fibreglass bodies but I can see the appeal of Elans. It would maybe be my next choice of a classic small sports car, well maybe a TR4. I like the look of MGB's but they don't go round corners very well (sorry to those here who have one - I still like the look of them). But I digress too much, sorry Malc.
Bill Bretherton

Bill
Don't get me wrong, I like elans, A std elan will outhandle most std cars. I've had mine since early 70's and will probably never sell it, but the std. front suspension is basically Triumph Herald and the rear an A arm on the bottom with a combined hub strut setup, It's all very light but the rear chassis frame which is fairly light pressed metal is prone to moving and cracking although in saying that I've never had an issue apart from a small crack in the front crossmember once that effected the headlight operation on a long hill
My comment on Midget suspension was more pointed towards, It doesn't need all the whiz-bang bolt on extras to make it work, it's main issue is the front springs are way too soft (std) and so is the front swaybar
So a decent set of springs and swaybar, beefed up swaybar brackets, good bushings everywhere and shockabsorbers up to scratch and a Midget will outhandle most cars -They don't need tramp rods and Panhard bars etc if everything is set up right

willy
William Revit

Thanks Willy, that's interesting.
Bill Bretherton

Oggers
Just out of interest, how do you get on with your GRP bonnet, does it bend much--When I had mine it would blow up in the middle like a balloon on full hook and ended up having to have 6 bonnet pins to keep it under control
William Revit

I by no means have Willy's depth of experience in such things, but I would agree that the best thing you can do to turn a Spridget from an "old" car into a "sports" car is to put in some stiffer front springs.

Malc.
Malcolm

Malcolm
I'm gluing an MGA twincam engine together at the moment and cleaning the sump up thought Malc. might like a look at that so here you go---wouldn't work on your car with the pickup over one side like you have, but if you modified your pickup to be central and had 4 blades like this but probably a tiddle longer towards the centre--it would be good and then a flat plate over the top just below oil level to stop it all splashing around
With the twincam, they've extended the sump out the side a bit for more capacity. Considering it's age and the fact it was basically a road car, it's not bad really

cheers'
willy






William Revit

Get that searing hot and chuck a couple of steaks in there. You would get some lovely grill lines! :-)

Malc.
Malcolm

Willy

I think having a standard Migdet set up at the rear and an engine with over twice nominal bhp as the original up front, anti tramp rods/bars are not a bad idea. There seems to me an appreciable risk of twisting the axle or damaging the springs.

GRP bonnet is fine enough. Some fiddling at the slotted mounting bolts up front, but otherwise it does not seem to flex too much. Held in place near the base of the A pillar with Spitfire bonnet latches, and I guess further reinforecment could be accomplished with over-centre latches - but they would spoil the lines somewhat.
Oggers

Oggers
i wasn't thinking, again, I guess you have a one piece front , On my midget it was just the std midget shaped bonnet so nothing really to support it's shape
with the springs i ran an extra half leaf in the front half of the spring and a big gas shocker from the top of the pumpkin down through the body to the passenger side seatbelt mounting point-absolute 100% no axle tramp from a full hook standing start and nothing to bind the movement of the axle in corners or on rough tarmac--and no skipping around under hard braking like you get with tramp bars-
willy
William Revit

Malc, I will take one of your front triangulation kits please. I seem to have 3 pairs of lever arms so there is bound to be one good set amongst them. Also I don't want to use my spare front line kit on this particular midget.
Does it increase the negative camber too? Or am I just being greedy :-)

Thanks
Matt
Tarquin

Drop me a message Tarquin at chevalierclassics@gmail.com

Cheers,
Malc.
Malcolm

Malc

Seen this: http://www.spridgetguru.com/TA0012_files/MgMdgt1500CompPrep.pdf

Guess mostly covered in Daniel’s later book.

Cheers
Mike
M Wood

Thanks Mike,

Just been reading through it, always interesting to get another perspective. A lot of it is familiar, it is probably the source of most of the regurgitated wisdom on the 1500.

I think I have covered most of it, in one way or another, although it is lacking a chapter on ECUs ;-) Looks like I am good to go!!

For those still following - the engine started up a couple of weeks ago and I bedded in the cam. Then I got distracted and decided to start on the mapped ignition bit (wasted spark using a VW Golf coil pack) as well as a whole load of wiring tidy ups and wrapping the new looms.

Hope to be running by the weekend as MOT is booked next week.

Cheers,
Malc.
Malcolm

This thread was discussed between 02/03/2021 and 13/04/2021

MG Midget and Sprite Technical index

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