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MG Midget and Sprite Technical 20 years later BBS discussion at MG-Cars.info
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MG Midget and Sprite Technical - 20 years later
| Gradually getting the engine bits together for a rebuild. Poor midgey had been laid up for about 20 years now - so quite interesting to see what the inside of the engine was like after this long.. Have pulled the head and block and have all the bits out and so on.. piston rings completely stuck in the piston grooves - mostly broke up when I tried to get them out Pic below shows what they looked like after 20 sitting still... 
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| John Barber |
| Second pic shows how they have cleaned up and after rings are out.. New set of std rings ready to go on.. Have had the block glaze busted and also interestingly no lip at the bore top desite 75k on the clock.. have checked all the oilpassages and waterways and they all seem pretty good depsite that long sitting... Also bought new rod bolts ! 
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| John Barber |
| Did you disolve the carbon, or scrape it the hard way? |
| Lawrence Slater |
| Have the grooves worn at all? i.e. are they still within tolerance for standard rings in the width of the grooves? I would also take it that the staining down the side of the piston before clean up was from blow-by when last running, rather than anything to do with it then standing for 20 years. |
| Guy |
| Setting the distributor static timing for an electronic version is exactly the same as any other. Simply set the engine at the desired static timing (7 degrees BTDC would be a good pre setting) remove no 1 spark plug and place against the block, ensure dissy is clockwise of the number 1 cylinder. Now gently turn the dissy anti clockwise until the plug sparks at which point it is spot on. Very very easy. :) However not sure if your problem isn't fuel related, is your choke working? new engines require loads of choke... |
| Robert (Bob) Midget Turbo |
| Mine has 78k on the clock John - but has been running - also no lip at the top. No glaze for me either - so I just left the bores and pistons well alone. Can't believe we all are doing 1500 engine and gearbox rebuilds at the same time |
| C L Carter |
| Just need to update I am questioning the direction the dissy turns in my mind? Can someone confirm the direction of the dissy on a 1500 engine please When setting the timing mate you need to turn the dissy body the opposite way to the shaft. |
| Robert (Bob) Midget Turbo |
| Sorry Bob - can't say as mine is all in bits ..? |
| John Barber |
| Bob Have you been sniffing thinners? |
| Dave O'Neill2 |
| Lawrence regards carbon on the valves I ued wet n dry in the pillar drill, regards pistons and head I had them both washed with all the other bits - cost a tenner -but after that most of it came of easily with a blunt scaper.... |
| John Barber |
| Thanks John. |
| Lawrence Slater |
| Got my new rings and have fitted them okay - Grooves don't appear worn at all instructions in the Ring packaging said Top ring gap 0.005" max - mine came in just below 4 thou - so seems okay to me. Checked ring gap in the bore that cme up at around 10 thou..Instructions said between 3-4 thou per inch of bore diameter.. So that means anywhere between 9 - 12 thou.. So 10 is just fine... Took ages to get the old composite head gasket remains off the top of the block !!. Next step is checking thrust washers - them I have to order them.... |
| John Barber |
| With your new rings fitted to the pistons, can you get any feeler gauage into the groove alongside the ring? If so, how much? Do you know what is acceptable? |
| Guy |
| Guy, the ring instructions said no more than 5-6 thou gap with the ring in the groove - I could only get 4 thou feeler in - but very tight - so gap less than 4 thou. |
| John Barber |
| John, Sorry, I should have read your earlier message properly! When I saw "ring gap" I thought it meant the gap between the two ends of the ring when inserted into the bore. 4 thou sounds like your ring grooves have worn very little in their 75,000 life! Pretty good, I would say! |
| Guy |
| Yes I am quite amazed at the state of the engine generally - there are some marks - the blowby signs on the pistons for example - but bores and crank and Head in the main look fairly good... |
| John Barber |
This thread was discussed between 31/03/2012 and 08/04/2012
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