Vance---Hard to know what's changed, since your history since the mods
are incomplete. A couple of suggestions here may help isolate what is or
isn't happening:
If the engine consistantly isn't happy when restarting from a warm
condition, pop the hood (latch) as soon as you shut off the engine. This
escape hatch may be enough to let out engine heat. At least make enough
difference to where you know it did or not. Take it from there.
Feel the carb bowls before starting up the warm engine. They should not
be so hot that you can't hold them.
Check that the water is going thru the intake manifold. This regulates
the temp. within a working range.
Plug color is given by what the plug sees during most of the driving. It
could still be too rich or lean at idle speeds. A quick check here is to
introduce more air at idle by creating a (variable) vacuum leak. If the
engine speeds up, it is rich. If it slows down or stumbles, it could be
lean.
By the same token, one can blank off (by hand) part of the air coming
thru the filters or it's canister openings. If the engine speeds up
after restricting the air flow, it's too lean,
and VV.
The above should be enough info to get you into trouble!
Dick
From: vance.navarrette@intel.com
Folks:
I have been driving the
6 more in the last week than I have in the 3 years preceding. 'Course
considering the fact that the 6 was sitting in the corner of the garage
in boxes for the last 3 years may have something to do with that...
Ahem. Back to the
original intent of the message.
I have noticed a
tendency for the 6 to idle roughly when first started after being driven
and parked for more than a few minutes. If I drive it down the road for
a mile, the idle smoothes out nicely. The car never hesitates, burps,
misses or does anything else that indicates a problem. Just the rough
idle immediately after a warm start.
My spark plugs read an
even grey/tan color. Timing is stock 10BTDC static, 4ATDC dynamic. My
compression is 9.6:1, and I have a 270 degree camshaft, stock exhaust,
stock ignition, ZS carbs with B1AR needles. The mixture fine adjust
screw is fully closed, and I have set the deceleration bypass valves per
Bentley. Warm idle is about 900 RPM, cold idle is about 1500 RPM with
the choke engaged. I never need to use the choke once the car is warm,
and it will start effortlessly when it warm. All emissions systems are
in place and working.
I have been thinking
about this, and it seems to me that this may be heat soak of the carbs.
I rebuilt the carbs ages ago, but never touched the mixture temperature
compensators other than to replace the covers. My car will not pass the
"lift the slide" test when idling, but I have been attributing that to
the cam.
Any suggestions as to
what to check? I am suspicious of the mixture temperature compensators,
but that is just a WAG. Fuel percolation? Lean idle mixture?
As always, thanks for
any help.
Vance
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