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MG Midget and Sprite Technical - Midget Revving

Hello, I am a new comer to this site, so hi! I have a 1978 midget that has a revving problem, when cold, tick-over is as it should be and sounds as sweet as a nut, but when warmed up and stationary, I.E when stopped in traffic the revs shoot up. I have recently serviced and tuned the carbs, adjusted the timing and points etc and fitted a new accelator cable, but still the problem occurs, could it be the advance-retard at fault? Many thanks, Sally.
S Corah

Welcome to the forum Sally, I am sure someone will be able to help you on here.

Just to clarify, do the revs actually "shoot up", for example you are stopped at lights and the revs increase without you touching anything, or do you mean the revs do not return to the correct idle speed when the accelerator is released, after reaching the lights?.

The former is odd but the latter could have a few causes.
JB Anderson

Yup - there's a number of reasons - first question is - did you fit a spitfire or bike chain for your accelerator cable as the 1500 is a bit jerky; secondly - have you got a heatshield fitted; thirdly - have you got a heavy right foot :)!!!!!

When you say tick-over is where it should be - where have you got it set? Lots of people have it a bit too low for the 1500, and so it will creep up when hot.

What advance have you got?

LOL - probably better to tell a tad more - it's a great forum, but, don't forget we can't see or hear the problem, so, the more basic you can make the description, the better the diagnosis suggestions you will get ;)

Enjoy your car - and hope you're coming to Midget50? As you're in Devon, will you be coming to "Norfolk Week" organised by the MGCC Devon and Cornwall group?
rachmacb

Hello, many thanks for your help, much appreciated! As you pull up to the traffic lights and stop, the revs creep up, to around 1500rpm (without me touching anything, feet off the pedals). If i lightly touch the accelerator the revs will drop back down to around 900rpm but in time go back up again.
I did fit a new accelerator cable but it was really stiff and jerky so I ordered another one, this time from the MGOC, and that gave the same problem! I have had to put the old one back on.
I am not a member of the MG owners club as I am quite young and feel that I may not blend in so well as a result but I would love to meet more Midget owners and have read about Midget50.
Thanks again.
S Corah

I think you need to get the cable sorted first so that you can be sure the carb. linkages are all returning to the correct idle position, and staying there.

There are various solutions to this, the simplest as Rachel would possibly suggest is to try a Spitfire cable which should fit straight in (hopefully she will be back soon to give more detailed advice!), or make up a cable using a telon coated push bike brake or gear cable, which is what I use.
You have to cut it to length and make up at least one "end" for it so it is not so easy.
Mine has certainly completely cured the jerkiness that was present before and the sometimes higher than usual idle.

If the cable sticking is not the cause of your problem then we will have to think again.
JB Anderson

Hi Sally, I'm a member of MGOC but never go to meeetings anymore, I was many years ago a member of the Midget and Sprite Club and think that might suit you more

Great to hear you've done some servicing work on the engine (and hopefully the rest of the car) so I think you'll appreciate my usal advice to (new) owners even though you've already cover some of it (perhaps you already know it all already)

Evens those wh've had their cars for a few years can learn from the owners Handbook

My advice to new or potential owners -

Buy an owners Handbook as it tells you so much you need to know as to own, drive, service and maintain your car - http://www.mgocshop.co.uk/catalog/Online_Catalogue_Handbooks_5.html

Always have the battery in good condition and all battery connections and leads clean, secure and protected, same for all electrical wiring and connections

As soon as possible do a full and proper 36,000 miles service only miss out items that you have 100% proof have already been done very recently, including;
g/box and back axle oils
brake and clutch fluids
coolant
dissy cap, rotor arm and leads (buy good quality ones) - http://www.distributordoctor.com/rotor_arms.html
fan belt

For a coolant change drain the whole system - engine block, rad and heater matrix if you can get any of these out to give them a good shake at the same time as flushing and back flushing then all the better - the sequence is flush, back flush, flush, clean, flush, back flush and flush again until the water runs clear, refill with the correct coolant mixture but bear in mind in tap water isn’t always the best water to use

Also change the rubber coolant hoses to silicone when you get the chance as new rubber ones tend to be poor quality now- http://www.classicsiliconehoses.com/

Be aware that brand new parts can sometimes be faulty, especially electrical bits (see just above) so don’t discount them when problem solving just because they are new, buy good quality parts

Check the age of your tyres if they are 6 years old or more replace ASAP regardless of tread depth, this will improve the braking, steering, ride, handling and possibly noise and safety of the car greatly

Use the car regularly - to get used to it, sort out any wrinkles and prevent the problems that occur with lack of use, and to enjoy it

Every few weeks check your horn, wipers and all switches work and heater valve turns on and off (all no problem if you use the car regularly)

Follow regular checks, servicing and maintenance as per owners Handbook

Drive in all weathers, the Midget hood should be very watertight if fitted correctly and the heater is more than adequate, if working correctly, for the small cabin

Do not do any cosmetic or improvement work for at least 12 months of regular use, unless you need to replace parts or components, as you may need to use the money elsewhere on the car

Also very useful, you can get suppliers catalogues for free to get you started to see where things go but in my personal opinion they’re not as good as a paper copy like - http://www.mgocshop.co.uk/catalog/Online_Catalogue_Parts_Lists_3.html

Cheers, enjoy your car
Nigel Atkins

1500 isn't actually too far out - they will creep up when idling, but, as it's not any higher than that - don't worry too much.

The MGCC Devon and Cornwall lot are a nice bunch and do lots of things and are pretty active, so, see where they meet (apart from the week they are in Norfolk ...!)
rachmacb

Welcome Sally,
You say "I am not a member of the MG owners club as I am quite young and feel that I may not blend in so well".
You cannot be too young. I started driving a Midget when I was 19 and joined the owners club back then. My daughter is taking me to Midget 50 in her Midget, she is still 17 and loving every minute of Midget fun she can get! She has been a member of the MGOC since she passed her test.
You don't have to socialise if you are a member of the MGOC but most of them are really nice and very helpful.
Dave
D Brown

Check if the butterflies in the carbs have over-run valves in them (you can look with a torch once the filters are off). If you have, that's the problem. Solder them shut and all will be well.
D le Versha

Good thinking D, worth a check.
JB Anderson

Check the throttle return springs that connect to the carb heat shield.
Rob Storer

This thread was discussed between 14/05/2011 and 16/05/2011

MG Midget and Sprite Technical index

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