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MG MGA - Recent incident

Car started making nasty squeaky noises while on an outing yesterday. I was convinced it was a tight bearing on the Dynamo, so crossed my fingers on the way back, 60 km. On the way, started popping in the exhaust as well, lots of power still but not happy at low rpm.
Anyway, got home, loosened the belt and dynamo and water pump turning free.
Turned inspection to carbs - found a 3/8 nut nesting on the throttle shaft, front carb. Top nut holding on carb had come completely unscrewed and been resting there for at least 60 km. Tightened up all carb nuts and everything running fine now.
However, also noticed the vac line was loose at the rear carb take-off (impossible to access) and the line had broken off at the bottom of the separator thingy. Crimped the line flat to limit leakage, so I'm running with no vac advance and maybe a bit of air leakage, but seems fine with good tickover, and strong pull and good mileage.
Do I really need vac advance? It's set at +8 static.
Art Pearse

Vacuum advance has naught to do with full throttle power or acceleration. It is good for better throttle response off the line, and better fuel mileage at steady cruising speed, maybe 10% better overall fuel mileage. With better thermal efficiency and less fuel consumption it should also run a little cooler at cruise speed. Good idea to reconnect the vacuum pipe.
barneymg

OK thanks Barney
Art Pearse

So, Barney, is it OK to reconnect the vac line without the separator?
Art Pearse

yes
Dominic Clancy

Thanks!
Art Pearse

It would work without the fuel separator, for a while, but not a good idea. The ported vacuum tap on MGA is positioned in the bottom of the carburetor throat, downstream from the main fuel jet. It is subject to ingesting liquid fuel. If the fuel gets into the distributor vacuum unit it can damage the rubber diaphragm. I wouldn't do it. Reconnect the fuel separator as soon as possible.
barneymg

This thread was discussed between 12/08/2018 and 15/08/2018

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This thread is from the archive. The Live MG MGA BBS is active now.