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MG MGB Technical - Fuel gone bad?
I'm trying to get the engine on my '71B engine to run to a degree where I can drive the car down to the local mg specialist to have it fine tuned. While the engine was being rebuilt by a machine shop, I had the carbs stripped, cleaned and rebuilt by the MG guy. I have re-installed the carbs and balanced and set the idle controls etc. but I have not changed the mixture control as the guy has done a preliminary setting when they were rebuilt. Static timing is 10deg B.T.C. New plugs and leads, almost new points at 15 thou'. But, The only way the engine will run is by either pulling the choke out, at which time it picks up and starts racing so I push the choak in a bit and then it starts to die, or by big bursts of throttle, then it starts to die. There is plenty of fuel getting to the carbs, but all I can think is maybe it's gone off. I filled the tank up last October and poured in a bottle of "regulator" or whatever it's called, but maybe 6 months is too long. Any comments appreciated. Ken |
K.G. Martin |
Ken As mentioned when we met last week, the engine has classic symptons of a weak mixture. The carb rebuider may have set the jets flush with the bridge as a reference point for starting the tuning process - you may be able to see by removing the filters and lifting the pistons. If they appear to be flush, you should lower the jets by rotating the adjusting nuts at the bottom the same amount on each carb - Haynes recommends two full turns (12 flats) as a starting position. You have nothing to lose by making this adjustment since by keeping a record of how much the nuts are turned, you can easily return to the as received condition. Appropriate adjustment should get you to a point where you can drive the car to the tuner. Good luck - see you soon. Barry 73B |
B.J. Quartermaine |
Hi. Modern fuel certainly does 'go off' with time, but not to the extent you describe in my experience. I agree with Barry that a weak mix is more likely, which may be the result of an air leak in the vicinity of the inlet manifold if the carbs are close to 'right'. HTH.. Don |
Don |
Ken I've only had fuel go off on me once and it was well over 12 months old. It had changed completely and had become a yellow liquid with a peculiar smell which was nothing like petrol. (Before the wise guys chip in here, no, I hadn't been relieving myself in the tank!!!!). It had also evaporated in the carbs and left a green/yellow sticky gum which was a pig to remove. It had coated the needles and jets and took quite some effort to shift and restore the engine to running order. I had to drain the tank which had only one gallon in. I put the rapid deterioration down to the low volume of fuel and large volume of air. Since then I've always kept a full tank over winter and so far that problem has not recurred. Dave |
Dave Wellings |
Thanks guys. I have trailered it down to the local MG mech who can play with the carbs to his heart's content. Just to show it has the upper hand, the bloody thing sprung an oil leak this morning while I was trying to get it going. It's from the oil filter adaptor plate connection to the block. The man can fix it, I've had enough! Eh up Dave, how's Yorkshire these days. My Mother in Law lives in Beverley. Cheers Ken |
K.G. Martin |
Na then Ken. Tha shud be sayin Ay up. Nor Ey up. Dunt tha now nowt? So thi muther in laws in Beverly eh? A see thas in Canada. Is that far inuff away fo thi? A bet tha needs a wullyat in thi B? Si thi later then. D. |
Dave Wellings |
Dave, Well it's been a long time and anyway I'm from South Wales. There's luvley then! So what's a wullyat when it's alive? Ken |
K.G. Martin |
I'll take a stab at that one: a wooly hat, for our less forgiving Canadian climate? Just reading that reminds me of my mothers comeback for bullies (lived in England as a child - I'm 35 now) : Who knitted you, woolyhead? Cheers, blokes! Dave |
Dave Whitehead |
Ha! of course. Tha needs a bigun over ere lad. Ken |
K.G. Martin |
Ken Thad probably be better off wea balaclava........... Si thi then. Dave |
Dave Wellings |
Dave, In Canada, it's 'eh', not 'ay'. Eh, Ken? Mike |
mike parker |
Eye it's eh 'ere not ay. I'm getting confused! Anyway, you will all be pleased to know that as of this afternoon, my 'B' met its match with the local MG mech, who has transformed the cantankerous beast into a docile and well mannered member of its class. Apparently the main problem was that the ignition was far too advanced. I thank you one and all. Ken |
K.G. Martin |
This thread was discussed between 02/05/2004 and 06/05/2004
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