Fellow Ford drivers,
I have a Carter YFA carburetor on my 250 engine. There are 2 screws for
idle adjustment with 1 screw resting on the idle cam. There is also a
throttle position solenoid on the side of the carburetor. Is the tps
adjusted by itself for the fast idle or is the idle cam screw adjusted to
get close to the desired idle speed - 600 RPM- and then the tps adjusted to
the final RPM speed? I know the fast idle is set while the car is in drive.
If the tps alone is adjusted for the fast idle is the idle cam screw
adjusted for the low idle (curb?) when the car is in neutral? I understand
that the throttle position solenoid should be unplugged.
From memory.... the two idle screws are side by each? With one on the cam
and one on the pivot screw for the cam?
If I'm right this far, base idle (shut down idle) will be set with the screw
resting on the pivot screw and curb idle will be set with the solenoid (the
idea being that the throttle plate should close slightly when the engine is
turned off to prevent after-run. Fast (cold) idle should be set with the
motor fully warmed up with the EGR hose off and plugged (if equipped). Some
also like the vacuuum advance hose to be disconnected and plugged - pretty
well need a shop manual to be sure on that point. Some carbs may have a mark
on the fast idle cam... if there is one, position the screw at the mark to
adjust to speed... If there is no mark, place the screw on the second step
(from the fastest end) of the cam and adjust to speed there. Sorry, not sure
of the correct rpm - memory wants to say about 1700 rpm...
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