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sjensen24
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Joined: 08-05-2005
Location: Brooklyn Park, Minnesota USA
Posts: 78
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I am seeking some car advice.

 

I have resolved a bunch of car problems this summer and my car was running better than ever.  For the last couple of days, however, I am experiencing a new problem.

 

If the car is not moving and I rev the engine, it runs very smooth and revs to high rpms.  When I am driving, at lower rpms, it seems to shudder, almost as if it were missing on one or more cylinders.

 

I have used a timing light to confirm fire to the plugs.  The plugs are new and are all a nice tan color.  I used a new toy to synchronize my carbs  a while ago.  Distributor has been rebuilt.

 

Any thoughts on where I should start?

 

Last edited on 08-17-2009 06:06 pm by sjensen24

Art DeKneef
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Joined: 03-12-2005
Location: Mesa, Arizona USA
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What was the last thing you did before the problem showed up?

Gas line plugged up some maybe? Fuel filter clogged? Fuel pump working properly?

What about the condition of the cap, plug wires, other wires in the engine compartment? You say the distributor was rebuilt. Are you sure that everything inside is still working properly?

That's what I would check first.

 

sjensen24
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Joined: 08-05-2005
Location: Brooklyn Park, Minnesota USA
Posts: 78
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No work lately on any running components.  I have been working on a steering problem and motor mounts.  I have a glass filter near the carbs and the fuel looks good.  The fuel pump is several years old but seems to work properly.  I have not checked the pressure.

The ignition is electronic, optical eye.  Distributor rebuild by a pro who specializes in Lucas.  All wiring is new.  Plug wires are several years old, but in good condition.  I see no fireworks under the hood when I run the car in the dark.

Only thing old about the distributor is the cap.  I left it on the car when I took the distributor in so as to simplify getting the wires in the right place.  I will replace it now.

dwalls1
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Joined: 04-11-2008
Location: Bloomfield, New Mexico USA
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I like to start diagnostics by squirting water on the manifold near the head. If done soon after start up this will confirm that all cylinders are running. For me at least, this is helpful, as my ear tends to decieve me. Good Luck

sjensen24
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Joined: 08-05-2005
Location: Brooklyn Park, Minnesota USA
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what would I be looking for?

dwalls1
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Joined: 04-11-2008
Location: Bloomfield, New Mexico USA
Posts: 207
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The cylinders that are firing will sizzle the water off immediatly. Any that are not running or misfiring will not heat up as quickly, and the water will not evaporate off. It's kind of like the way we used to check an iron for being hot enough.



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