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Author Topic: AC Unit Causing Engine To Stall  (Read 1494 times)

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  • American MGB Association
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  • American MGB Association
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AC Unit Causing Engine To Stall
« on: May 06, 2018, 06:32:46 PM »
I have a 1977 MGB which I have added a AC unit from Nostalgic A/C out of Ocala, Florida. The unit works fine but I have an issue with engine stopping at intersections because of the extra load from compressor.

I have a Weber (32/36 DGV DGEV DGAV) down draft carb on this unit. I am wondering if this could be my problem. Other than this the engine runs great.

I have been reading your posted info for years and want to thank you for service to us MGB owner.

Richard Ehrlich
South Padre Island, Texas
American MGB Association
phone/text: 773-769-7084

North America's oldest and largest club for all MGBs, MGB-GTs & Midgets.  A nonprofit organization founded in 1975 and offers color magazines, emagazines, technical advice, member recommendations on service shops, registration of your MG, a tradition of service & FREE member classified ads that appear in the magazine & on the website.


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Re: AC Unit Causing Engine To Stall
« Reply #1 on: May 06, 2018, 06:44:01 PM »
I have little experience with air conditioners, that’s a fact.  It must be that the idle is the correct speed unless the compressor kicks on – otherwise you would simply increase the idle.  That extra load on the engine is causing the stall, but it shouldn’t.  Take a look at your timing.  First of all, the vacuum advance should be connected from MANIFOLD vacuum (highest at idle and deceleration) directly (and not through the TCSA switch on the master cylinder box).  If you cannot get manifold vacuum (about 18 inches at idle) from the carb, then drill each leg of the inlet manifold, install a hose connection, then “tee” those two fittings to the vacuum advance.  (Using only one leg will pulse the vacuum advance diaphragm to death.)  Check the timing to assure that you have 32 degrees BTDC at full mechanical advance, vacuum disconnected.  This occurs around 3-4000 rpm.  You need a dial back timing light to set this correctly.

Hope this little bit helps.  Please feel free to call with more questions or for clarification.

John H Twist
John H Twist
University Motors Online
100 East Beltline Avenue SE
Grand Rapids, MI  49506


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