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MG Midget and Sprite Technical - sooty plugs
| hi all. car started running a bit rough and hard to start in the mornings. checked a few things over and found that when i took the elec ign module off and put points back it run fine, but plugs still getting sooted up after a few miles. tried to adjust mixture on carbs and one is fully adjusted up and won't go any further. plugs are black dry soot. ideas would be appreciated. thanks bob. |
| bob taylor |
| Black dry soot would indicate a rich carb condition Are all the plugs doing this or just 2 ... front or back What heat temp range are your plugs ? Maybe your plugs are to cold... What gap are you using... with modern day fuels you need a wider gap to counter all the crap in todays fuels You mentioned a couple interesting points, one carb is done all the way up, meaning its no longer funtioning and getting fuel from only one carb 2nd you said your electronic ignition is screwing up...which kit do you have? 1275 im assuming Prop |
| Prop and the Blackhole Midget |
| Ah... I just saw your spec page 1098 Prop |
| Prop and the Blackhole Midget |
| hi prop, just started doing it, all plugs the same. used same plugs since had car, gap ok. stripped carbs and cleaned. seem to have had loads of adjustment on carbs when was running right but all of a sudden adjustment not doing anything. pistons go up and down ok, no problem. elec ign that i removed was the accuspark. was wondering whether to try weaker needles but don't understand why happened all of a sudden. thanks bob. |
| bob taylor |
| What air filters are you running? |
| Dave O'Neill 2 |
| Floats gone bad suddenly letting fuel overflow onto the jet bridge? I take it you've checked to see the enrichment control isn't sticking causing the jets to remain down (you'll never adjust past that!) With both jets wound all the way up, the engine simply should not start or even run perhaps. Check your float heights and the height of the fuel in the jet (eyeball it with the piston removed). It shouldn't be too high that a wobble causes it to overflow into the venturi area. Do the same check with the ignition on to make sure the pump isn't forcing fuel past the float shutoffs somehow and going into the carbs. Regardless of all this, it might be wise to put both carbs into a neutral state (both jets set equally by eye) and reballance for both airflow and fueling from 'scratch'. |
| Roadwarrior |
| hi dave, standard filters, haven't altered anything for couple of years. hi roadwarrior, jets not sticking. have reset both carbs and started from scratch. run car for about 10 miles and looked at plugs, nice brown colour. 15 miles later black again. no fuel from overflow. bob. |
| bob taylor |
| hi, just thought could be filters blocked, never changed them. will remove tomorrow and see what happens. bob. |
| bob taylor |
| Thats the great thing about our carbs, they dont just go out of tune, they do break or need servicing but they almost never go out of tune on there own Sounds like the accuspark is throwing a tantrum...id stay with the P&C for the time being Prop |
| Prop and the Blackhole Midget |
| Maybe change the plugs, even for an old set. did you reset the gap on the plugs, is the gap on an electronic ign setup wider so going back to points means setting to normal gap? |
| mog |
| My first car was a Morris Minor - actually an Austin van. I had a problem with it running very rich and not revving freely. I checked all sorts of things trying to find the cause of the problem, but it finally turned out to be a blocked air filter. The exhaust was blowing where it joined the manifold and the air filter was sucking in the fumes. This caused it to run rich, which produced a sootier exhaust, which blocked the filter more, etc., etc. This could explain why the filter housing was empty when I bought it! |
| Dave O'Neill 2 |
| Hi Not an expert in these things but did have a similar problem many years back. It was the choke levers slipping. If u haven't done so already make sure levers totally disengaged both before and after test drive Good luck, Graham |
| g Victors |
| Ive got a new choke issue that showed up today...and im not sure what it is, I just dont have the time to mess with it at the moment...but somethig you might check into When I pull away from the stop light something is catching on the chock and.making the engine run rich and at a higher rpm at idle around 2500 rpm, So I have to pull the choke out at the next light for a few seconds and then the engine goes back to normal idle until I put my foot back on the gas peddle Strange Prop |
| Prop and the Blackhole Midget |
| It does seem to be running rich so check all things that could cause that - especially anything you have fiddled with over the past week! Do check the ignition settings again..... I second the choke check. HIF 44 on mine was not set correctly on the cam.....Other possibilities - flooding - perhaps float needle not seating correctly - clean it out or replace, floats themselves leaking - change for new or solder them up, vac advance hose come away, etc.... Cheers Mark |
| Mark O |
| hi all, car running ok now, think it was a combination of things. mainly electrical. took elec ignition off as think it was playing up, put 3 different condensers on till eventually it run better, new air filters as others looked like they were originals.carbs weren't very tight on inlet manifold. now my rev counter needle jumps up and down now and again. bob. |
| bob taylor |
| ""carbs weren't very tight on inlet manifold. " Yeah....those are some small words, but a HUGE problem...fixing that is going to make a big differance Id look at the washers holding the manifold on...if these are off the shelf regular washers they tend to distort thus causing a loose manifold... if they are the commons, then replace with some grade 8 flat washers and that will cure any washer distortion Congrats Great find and job well done Prop |
| Prop and the Blackhole Midget |
| Opps... sorry, I got ahead of myself....I read that and was thinking manifold to head...never mind the grade 8 washers...your good. Prop |
| Prop and the Blackhole Midget |
| after a couple of days i was still not happy how it was running and then i noticed that the ht lead to the coil was the early screw in type and the coil was the push in type. P O had took the screw part off and replaced with the rubber cap used on the push on type so only had the wire with the small brass washer on the end which didn't fit in the coil properly. cannot believe it run ok for 3yrs. with my fiddling about it must have gradually come further out the coil. bob. thanks all. one thing i must remember,,90% of fuel problems are electrical. how true. |
| bob taylor |
| Hi Bob Pleased you got to the root of the problem You are so right. 90% of problems are electrical. The other 90% are fuel related! Graham |
| g Victors |
| And the other 90% are mechanical. Waht about the remaining 90%? |
| Lawrence Slater |
| Ah well those must be operator error :-) |
| M McAndrew |
| Or rust... |
| Peter Blockley |
| hi all. have ordered 2 new jets for my carbs after discovering i had 2 different jets which 1 could not be adjusted properly. when setting them up again from scratch i know you have to level them with the bridge and then how many flats was it, up or down. thanks bob. |
| bob taylor |
| Hey bob... Ive got the same issue... 2 differant jets, I used a flat washer on the jet where it slides into the carb body to level out the differance How many flats... well, thats an interesting question ...the "book" and haynes both say 2 complete turns (12 flats) down from the carb body, but with todays fuels and filters and typical modifications, id use 12 flats as a starting point and adjust from there mostlikely to more fuel rich. If having to make a choice, Id perfer to be 2 rich rather then 2 lean Prop |
| Prop and the Blackhole Midget |
| I would suggest the incorrectly adjusted and non-satndard jet is the root cause of your sooty plugs - if jet is too low, you will get overfuelling and a rich mix. As Prop says, better to be rich than lean though. Setting up is pretty simple once the correct jets are in place - Google is your friend....try the SU website also..... |
| Mark O |
| hi all, just to let you know all sorted i think, new jets, run out for a couple of hours yesterday and all fine. mot next sat and away we go again. thanks bob. |
| bob taylor |
This thread was discussed between 07/03/2015 and 21/03/2015
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