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Pretty Crazy Misfire On My 1275 A Series


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#1 SomethingNew71

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Posted 24 August 2012 - 06:18 PM


1960 Morris Mini

Austin A Series 1275 from an Austin America

Dual Hs2 Carbs

Stage 2 exhaust manifold


Alright so I got my mini back after a minor fender bender and the car is running like crap. I have a 1275 with dual HS2 carbs on it. Ran alright until recently. When accelerating under load between 0-2500ish RPMs the car is stuttery and feels underpowered. Then above 2500 it smooths out and begins to run properly(ish). Upon shifting gears the whole process starts over. I have gone through and checked the spark plugs and they were pretty black after running a bit they golden out though. I replaced the spark plugs with new ones and the whole problem just got worse. I also made sure not to mix up the firing order. Both m SU's have been cleaned to make sure there wasn't any crap in them and they were good. The fuel pump is also running properly. Does anyone have any ideas as to why this may be happening? Things to check?


#2 Cooperman

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Posted 24 August 2012 - 06:22 PM

Check ignition timing, fuel/air mixture, fuel levels in float chambers, carburettor balance, carb. linkages, points gap, ignition leads, oil in carb dashpot, air leak in manifold gasket or enclosed breather system (if fitted).
If none of that works come back on here.

#3 SomethingNew71

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Posted 24 August 2012 - 06:23 PM

Got it!! I'll check it this weekend and report back. :proud:

#4 jimnali

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Posted 24 August 2012 - 08:24 PM

Fender bender - is it possible that the carburetter jets could have been bent by hitting the bulkhead engine in the collision. I don't know about twin carbs but my single carb is very close and quite a small movement of the engine could allow the jet to hit the bulkhead. Are the bushes in the engine steady okay?

#5 jedduh01

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Posted 27 August 2012 - 03:29 PM

Does it run any better with the choke out a bit???




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