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MG Midget and Sprite Technical - My car spec - maybe I got carried away...?

I have over the past while been trying to list out everything I have done on my car. A sort of theoretical exercise in if I got run over by a bus tomorrow, I had better give the next custodian half a chance of figuring out what he or she is dealing with! Also a way of taking stock of all the work I have put into the car over the years.

Things have clearly got out of hand over the years... as it's ended up quite a long list! :-D But I thought some of you might enjoy it, it might inspire people to do some mods/improvements or create some chatter on how/why I have done what I have done. I can get some pictures too if there are specific bits you are interested in.

The picture attached is from circa 2010, when I had NO CLUE and NO TOOLS other than a 1/2" drive socket set. I compensated with enthusiasm and the stupidity of youth! I and it have come a long way for sure.

The full spec as it stands today:

SHORT BLOCK
• Bored 20 thou (1512 cc).
• Centre main oilway enlarged to 5/16”.
• H-section lightweight rods with ARP fasteners
• Balanced rods and pistons
• Balanced crank, flywheel, clutch and pulley.
• Crank end float ~4 thou.
• Custom crank pulley with 36-1 trigger wheel for injection/ignition systems
• Flywheel lightened (7.3kg to 6.2kg)
• All crank journals ground 20 thou under.
• Piper 285 ultimate road cam.
• Uprated tufftrided cam followers.
• Baffled sump, modified oil pickup pipe.

HEAD
• Lightly ported head (casting ridges and flash removed).
• Four angle valve seats, blended into port.
• Larger inlet valves (1.44”).
• TR6 valve springs.
• Bulleted bronze valve guides.
• Hardened exhaust seats (for unleaded fuel).
• Skimmed approx. 90 thou to give ~10.5:1 compression ratio.
• Rockers bushed with bronze bushes.
• Rockers shimmed 30 thou.
• Shorter push rods (early Spitfire, 60 thou shorter).

EXHAUST
• Custom designed 4-1 exhaust manifold, equal length runners, tuned for approx. 5200 rpm peak.
• Custom 1.75” exhaust with twin straight through silencers.
• Wide band lambda sensing in downpipe for ECU “self-learning”
• “Titanium” heat wrapped manifold.

 
FUEL SYSTEM
• Custom fuel injection system using Speeduino NO2C ECU
• MG 48 mm alloy throttle body
• MG Maestro coolant temperature sensor (ECU temperature)
• Ford inlet air temperature sensor
• Ford (?) crank position sensor
• Bosch Land Rover “Thor V8” injectors.
• 044 style pump mounted on rear bulkhead
• 3 bar pressure regulator and return to tank at rear bulk head.
• 8 mm fuel line.
• Custom stainless steel inlet manifold with flared port runners.

IGNITION
• Fully mapped wasted spark ignition.
• VW Golf mk.5 (and other VAG) coil pack.
• Custom 8.5mm performance HT leads.
• Bosch WR7DC+ spark plugs gapped at 31 thou (0.8mm)

MISC ENGINE
• Thermostatically controlled oil cooler.
• Modified/uprated front engine mounts using standardised bobbin AVMs.
• Alloy rocker cover.
• PCV from head to manifold via catch tank.
• Ford Ka on-off idle air control valve (for warm up idle).

ELECTRICAL
• Speedo and tacho lights come on with headlights (not dash light switch)
• Headlight relays for low and high beam, H4 bulb conversion
• Motorcycle brake light switch (pressure activated) with relay
• Tim gauges (oil pressure, vacuum, temperature, fuel)
• Relays, blade fuse box and custom loom for fuel injection and ignition electronics
• GPS speedometer
• 8” electrical coolant fan, 95 on – 85 off thermostat and relay.
• High flow 120mm axial fan for heater with PC-ABS 3D printed adaptor
• All wiring alterations integrated into re-wrapped main looms.
• fuel pump isolation switch.

 
REAR AXLE
• “Growlerised” half shafts (machined splines and shot peened).
• 3.55 final drive ratio.
• Blackline helical ATB LSD.
• Longer wheel studs for use with alloy wheels.

BRAKES
• EBC Yellowstuff pads
• Solid discs
• Minifin alloy rear drums
• Stainless braided hoses.

GEARBOX AND CLUTCH
• Clutch mechanism all re-bushed to remove slop
• New clutch.
• Custom machined front gearbox/bellhousing for lip oil seal
• Remote clutch bleed.
• Gearbox end floats set to minimum specs
• Shortened gear lever for short shift

SUSPENSION
• Custom designed front damper triangulation link.
• Uprated front shock valves.
• 11/16” anti-roll bar.
• “Strut brace” between front dampers.
• 360lb/in front springs, lowered.
• Rear lowering blocks (1”).
• Custom designed anti tramp bars to avoid binding.
• Poly-bushed rear suspension.

WHEELS AND TYRES
• Rostyle steel wheels with 155/70 R13 tyres for road use.
• Minotaur Minilite style wheels with 175/50 R13 Nankang NS-2R tyres for sprint/track use.

 
INTERIOR
• Toyota MR2 seats modified with harness slots.
• Four point harnesses
• Roll over bar with harness bar
• Leather steering wheel
• Clutch foot rest.

MISC
• Removable front chin spoiler


FLUIDS
• Millers Classic Sport 20w-60 Semi Synthetic (Engine)
• Millers Classic Gear Oil EP 80W-90 GL4 (gearbox)
• Millers Classic Differential Oil 85W-140 GL5 (Axle)
• Dot 4 brake and clutch fluid

IN THE NEAR FUTURE...
• Hood removed, custom tonneau for summer use. Lightweight hard top for “winter” use.
• Fibreglass bonnet
• Fibreglass bootlid with spoiler.
• Drilled and grooved brake discs, Mintex M1144 pads.


Cheers,
Malc.



Malcolm

Blimey. You were young in 2010? I've gotta go back to circa 1970 to fit that description. 🤣.

But anyway, that's *some* list. 😉. 👍

I've never had to 'invert' before, just to see the end of a single post. 😆😆

anamnesis

nice list Malc-I can see some heavier front springs coming and a bigger bar
William Revit

Anam, I started my mid-life crisis early!

Willy, at the moment I am happy with the handling. I only put on the 11/16" bar last year and it's pretty nicely balanced for road/track use.

Malc.
Malcolm

Congratulations Malc, that's quite a list!

Do you have any photos or details of the strut brace you fitted between the front dampers please? My car has a K-series conversion by Moor Lane Garage and that required chopping out some of the front cross member. I've often thought that a strut between the dampers would help to remove any flex that the chop might have introduced.

Thanks,
Jon
Jonathan Severn

Will do Jonathan. I meant to take some pictures when I was in the garage last night... but forgot! Watch this space...

Cheers,
Malc.
Malcolm

Malc
I think it's great what you've done - we only have one life so do something that interests you (within financial and domestic constraints obviously, well, the latter is negotiable!)
Bill Bretherton

Malcom,
you forgot the bodywork! It's getting on 8 years since we met in that lockup to get the rear wings shaped! It must be ready for a proper coat of paint by now :O)

Best of...
MGmike
Retired and in the garage
available for project support if required :O)
M McAndrew

Eager to see the £/BHP gained figure.
Rob
MG Moneypit

@Jonathan, (if you are still there?!) Pictures of the brace. Couple of rod ends, a couple of brackets and a bar. Brackets are only that shape because they were scrap from my triangulation link prototypes. If I were to do it again I would make them thicker (they are a bit flexy at 4mm). Things have since been tidied up, like the washer stacks have been replaced with proper spacers!

@Bill... yeah... I got divorced three years ago. Ha ha ha! The car wasn't to blame, but it did provide useful escapism.

@Rob, it will be a very high number!!!






Malcolm

Thanks very much Malc, that's really helpful. I love the simplicity. When I started thinking about it, I was wondering how to bring the strut forward of the shock mounts (the obvious mounting points) while keeping all the load paths as straight and short as possible.

Although my car has a Frontline telescopic conversion, I think the basic concept would still work.

Now I just need to get around to doing it...

Cheers,
Jon
Jonathan Severn

Yeah, the load paths aren't great! But it works OK.

I made a short video at the time I first installed it. I took the nut off one end so it was free to move and jacked it up under the chassis rails/cross member so both wheels were off the ground. I could see as I was jacking it up and when I lowered it back down onto it's wheels the bolt/rod end moving and twisting. Not a huge amount, but easily visible with the naked eye. It shows it is flexing and a stay bar will reduce that.

Malc.
Malcolm

Good stuff Malc. You seem to really have enjoyed the technical challenges of dreaming up and carrying modifications to your car. I certainly have enjoyed them, plus benefitted from the insight. Not forgetting your solution to rear hub gasket availability in a range of correct thicknesses was to make some and make them available to others as well as rebuild kits for lever arm dampers.

Does not seem that long ago you were first on the BBS when you were thinking of buying your 1500 and then its early sagas.

Cheers
Mike
M Wood

Thanks Mike, so many sagas!!! ha ha ha. It was 2010 I bought it. 13 years of entertainment and hanging around on the BBS!

I was looking through some of the the old pictures I have and thinking FLIPPING HECK there has been so much time, effort, money and thought gone into this wee car. There are more things that I have forgotten about than I remember having done!

But this really is the final iteration now! Honestly! It will just be maintenance and tidying up the cosmetics from now on.

Malc.
Malcolm

Malc

What’s the next project then…

Cheers
Mike
M Wood

Lots more resto work I want to do on my Alfa GTV V6...

And I keep thinking about moving house. That ongoing project called life!

Malc.


Malcolm

This thread was discussed between 29/03/2023 and 06/04/2023

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.