My MGB runs really well, starts on the button, ticks over smoothly and pulls well without flat spots or pinking, but I can’t seems to get rid of what feels like lumpy running on very light load, ie cruising at 30-40 mph on the flat.
Engine is over bored to 2000cc, lightened and balanced, 123 dizzy, I have tried various ignition timing settings and 14 BTDC seems the best. The carb’s are good, rebuilt and with richer needles and accurately set up. Plugs are a good colour.
Any suggestions? The fact it runs so well the rest of the time is baffling.
thansk...
MGB lumpy running on light load
Re: MGB lumpy running on light load
With all the tuning that has gone on, have you had the car on a rolling road for a good set-up session?
from my bike racing days, sounds like a bit of over fueling going on to me..just a hunch though
Kev
from my bike racing days, sounds like a bit of over fueling going on to me..just a hunch though
Kev
Re: MGB lumpy running on light load
I have had a comparable problem with an a-series which was caused by low compression on a single cylinder. it sounded fine but a 30psi variance meant it stumbled a bit at 35 in top. Fitting hardened valve seats sorted it.
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
Re: MGB lumpy running on light load
Indeed - double check the valve clearances then a compression test would be a good start, and take it from there.
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