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MGB '73 mgb idle question

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mopease

mopease

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hi,

can anyone answer this question? my b has been idling @ about 1200 rpm's lately. when i depress the clutch, i notice the idle speed drops about 100-150. is this normal? i had replaced the clutch about 2 years ago, but have only put on about 1000 miles since the replacement. any thoughts are greatly appreciated.

regards,
eric
 
A slight drop in RPM is normal due to the added friction created by the throwout bearing.
Your 1200 RPM idle speed is a bit high; should be more like 800 or so.
 
aeronca65t,

thanks for the timely response. my b usually idles @ around 800. 1200 rpms is a recent occurence however. hope it's not signaling any pending doom. a carb adjustment perhaps.

regards,
eric
 
See if your choke mechanism is sticking: this can bring idle speed up. Work choke knob in and out while someone sprays the linkage with WD40.

Also, look for vacuum leaks.
Often can be a split hose (or one that has slipped off). A decent way to find vacuum leaks is to start engine, let it idle and spray around intake manifold and vacuum hoses with WD-40. If WD40 is sucked into engine, it will slow down a bit (and you'll have found your leak). WD40 won't hurt your engine.

Last year I saw an MGB that idled fast and it turned out to have a loose intake manifold. It was so loose, we could grab the carb and move the whole deal up and down about 1/2 inch.

Could be lots of other things, but those are common and easy to check.
 
I have had my carbs work loose in the past. A periodic check of the carb and intake manifold bolts should be done. You also might check hoses to make sure there isn't a leak there.
Bob
 
thanks to all who responded. i haven't had a chance to take her out for a spin as of late to check these things out. will let you know what i find out.

regards,
eric
 
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