That awful colour MGB GT

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Re: That awful colour MGB GT

Post by CLINT »

We have one in the family in the same colour. An heirloom that will be my sons at some point. The colour grows on you and really suits it. I much prefer it to the usual red and green ones.
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Re: That awful colour MGB GT

Post by SiC »

Something else of note is that I did a fill up yesterday. Going by the fuel gauge I didn't quite get it as full as last time, so the MPG calculation will be a bit higher than actual.

I did 191.5 miles and used 7.57 Imperial Gallons. This makes 25.3mpg for the trip to and back from Shitefest.

Seems quite low to me? Maybe I am running quite a bit richer than I thought.
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Re: That awful colour MGB GT

Post by fried onions »

If your carburettors are in fine tune based on plug colour after running on load hot, valve gaps are as specified and your brakes aren't dragging, try advancing the timing by turning the distributor clockwise (I think) a little. I recall you had electronic ignition? Hence no CB points gap.
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Re: That awful colour MGB GT

Post by fried onions »

I might add, when I got my station wagon it was returning mid 20's. I gradually weakened the mixture and advanced the ignition timing little by little until it now returns well over 40 m.p.g., remarkable for an elderly 1000. The carburettor is well worn as the jet adjusting nut is right at the top limit of travel with the mixture bob-on, so, like the almost 100,000 mile engine, needs overhaul. A job for the later months.
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Re: That awful colour MGB GT

Post by SiC »


fried onions wrote:If your carburettors are in fine tune based on plug colour after running on load hot, valve gaps are as specified and your brakes aren't dragging, try advancing the timing by turning the distributor clockwise (I think) a little. I recall you had electronic ignition? Hence no CB points gap.
It's electronic points assisted ignition. So points but dwell time and exact gap less critical.

I need to pull the plugs again for another looksie again soon. At SF they were on the blacker side. I think the fresh fuel that is flowing through is probably making it run tad richer than the 6-8month old fuel that I originally tuned it with.

As it's been running ok so far, I've hesitated from fiddling with it. Thus the static timing is whatever I set it to last year. It's not pinking, so I've left it as is.

Likewise the temperature is hitting quarter way between cold and normal on the gauge and stays bang solid still once warmed. So I've not wanted to change the stat to a winter one to get a bit more heat from the vents. Anyway it's supposed to be summer in a few days...
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Re: That awful colour MGB GT

Post by fried onions »

Oh aye. The age of the fuel you're talking here will have nothing to do with it. Weaken it by a flat or two after a 7 mile hard run. Hooli mentioned the thermotat, it's worth checking the rating at least because that too has a significant effect on fuel economy. You want it running as hot as practically possible, which means 70-80 centigrade indicated on the thermometer.
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Re: That awful colour MGB GT

Post by cros »

Electronic points assist type is fine I reckon. To clarify, 10 or 15 degree marking on distributor advance unit means 20 or 30 respectively at the wankshaft. Non functioning vacuum advance hits economy hard. Having led a sheltered life I only recently discovered that on Delco distributors the linkage is external so you can see if it's working just by tweaking the throttle open on an old Vaux.
On Lucas versions I connect a strobe up, pull off the little pipe and have a suck whilst watching the timing.marks; perhaps someone can suggest a more dignified method.
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Re: That awful colour MGB GT

Post by Hooli »

If you just suck on the vacuum pipe with the dizzy cap off you should see the baseplate move if it's working.
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Re: That awful colour MGB GT

Post by SiC »

Original dizzy vac advance definitely leaks and holds zero vacuum. This was a year or so ago.
Image

New cheapy Chinese dizzy certainly used to work, but not tested recently.
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Re: That awful colour MGB GT

Post by Hooli »

I'd expect high 30s at least from that on a run.
The book figures for my Midget were 26-28mpg, I once managed 47mpg on a run to Wales driving at the national limits & it never dipped below high 40s. Carb tweakage seemed to be the biggest thing on mine, the points dizzy was never a problem. I still recall it ran best at 11 3/4 flats when setting the carbs, it was odd how the rear always leaned itself off & the front went rich. I threadlocked them in the end & that solved it.
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