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Eric Swanson

In article .com,
says...
wrote:

Try injecting propane or choke cleaner into the air intake (leave air
filter and cover in place -- prevents fires in case of spit back) for a
few seconds. If the idle (set to about 550 RPM) smooths out (injecting
chemicals will make it speed up by as much as 200 RPM), suspect a
vacuum leak or a carburetor problem.

I can try that, using an unlit propane torch. Bear in mind that the
idle's not rough, just low. Nonetheless, I find it hard to argue with
such a sterling reading on my vacuum gauge. For the record, I'm getting
my vacuum reading from a port that leads to the vacuum chamber for the
car's vacuum-actuated cruise control.

You didn't mention the mileage on the engine. Consider that older engines tend
to have trouble with valve guide seals, which harden with age. A bit of extra
oil will seep past into the intake and may add to your HC emissions, especially
at low speeds when the throttle is almost closed. Also, your rings may be
allowing some oil into the cylinders. One final point to check, if you haven't
already done so, would be your PCV valve, which should close at high vacuum,
but may be so dirty or worn that it is not doing so, thus allowing excessive
amounts of gas into the intake manifold from the crankcase.

--
Eric Swanson --- E-mail address: e_swanson(at)skybest.com :-)
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