MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Where to start on a tune up?

Hi
After cleaning the head and dropping the sump - to cure leak - I have put the engine back together and with a jump start I can get the engine to run fast - 15000 rpm.
I want to tune it and have a manual BUT....

is the Haynes method Ok?
Is there a 'good' way?
How would or where would you start?
One piston in rear carb is slow to drop but all looks OK

Engine is 1256 and standard. I had it at the Aldon RR session 2 years ago and it was OK - has anyone got the article from then?
Cheers
Dave
Dave Price

Marry Christmas Nigel, enjoy your wet dream.

Prop

Prop and the Blackhole Midget

open goal - should I take a shot

ok, very quickly

have a look at the relevant copy of the Driver's Handbook as all the details are in there

check/set in this order -
tappets, CB points, plugs, timing, carb mixture

if you adjust any item in the above chain then you'll need to check/adjust all the items that follow it in the chain

set timing but using figures initially then by ear (and test driving as required)

best actual tuning you can do is to fully service the whole car
Nigel Atkins

thanks so far - I meant 1500 rpm of course!!
Dave Price

Oh come on nigel

You can do better then that, this is your shot, Manchester uniteds goalie just got injured, the team is calling you out from the stands to fill in....this is your big moment

Please try agian, id expect no less then 8000 words plus charts, graphs, and illustrations

This thread is the one thats been searching for you its whole life

Please nigel, dont play the innocent virgin now.

Go for it, swing for the fences... we are all pulling for you.

Prop
Prop and the Blackhole Midget

Prop,
I wasn't thinking of Wendyball, but ManU is appropriate as it is only supported by those that do not live in Manchester

Dave,
just seen that the piston in the rear carb is slow to drop - assuming it has the same oil and same level as the front then that may be a problem, might just need cleaning - petrol on a rag, clean the inside of the dashpot and outside of the piston then light oil on the piston rod only (not on inside of dashpot or outside of piston)

hopefully it's nothing to do with a bent needle, be very careful with the carb needles

or have the dashpots and pistons been mixed up, see - 41 Matching SU Air Pistons - http://www.youtube.com/watch?v=IfU47Oqq9wA

147 MG Carburetter Tuning - http://www.youtube.com/watch?v=4nvGLgO6pj0&feature=plcp

I assume you mean your engine is a standard 1275

Nigel Atkins

Agree with the order of Nigel's list, but I would add (unless you know for sure that these are correct):

First item, do a compression test - if a cylinder is weak it will limit what you can achieve. If you don't have a gauge, simply listening for any irregularity in beat as it cranks on the starter will do (disconnect the coil lead first so the engine doesn't kick).

Before setting the mixtures, check the carburettor float levels and adjust if necessary. Also check for play in the throttle spindles. Not as critical in terms of overall running, but a significant amount of play will affect the smoothness of the idle.

After setting the mixtures, take the dashpots & pistons out to check the height of the jets. If they are flush or protruding past the bridge then new jets and/or needles are required. If they are sitting too far down, it indicates a possible air leak.
Paul Walbran

based on what Paul has put I might have again misunderstood, I thought it was rear carb piston that was slow rather than one of the engine pistons and perhaps relying on that 2 year old RR set up too much
Nigel Atkins

Sorry - been away on a canal boat for a week or so thus the lack of replies. Pots might have been swapped - will try a clean and swap.
The rest will be tackled this weekend - if family allow it of course.
Thanks so far
dave
Dave Price

or have the dashpots and pistons been mixed up, see - 41 Matching SU Air Pistons - http://www.youtube.com/watch?v=IfU47Oqq9wA

147 MG Carburetter Tuning - http://www.youtube.com/watch?v=4nvGLgO6pj0&feature=plcp
Nigel Atkins

Ok - followed the video on the pistons Nigel and they were the wrong way round. Fitted once more and both drop fully so that's done.
Dave Price

great

see my first post on this thread and the link to '147 MG Carburetter Tuning' vid, taking into account what Paul's put about the carbs, as they've been "disturbed"
Nigel Atkins

This thread was discussed between 10/04/2014 and 20/04/2014

MG Midget and Sprite Technical index

This thread is from the archives. Join the live MG Midget and Sprite Technical BBS now