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From Holley Tech Service.
Hello
The first thing that you need to do is adjust your float level, no fuel
should run out the sight plug with the engine running. and check to make
sure that your fuel pressure is not over 7 PSI. I suggest 6-6.5 PSI Make
sure the acc. pump is properly adjusted. It should be at zero lash at
idle. and have at least .015" gap at Wide open throttle with the pump
lever pushed all the way down. Then try turning in the idle air screws
all the way in with the engine running.
If the engine continues to run with both screws all the way in, then
thecarb is letting fuel into the engine from someplace other than the idle
circuit. We have to find out where from and correct it (with the screws
all the way in the engine should die) Next you want to check the manifold
vacuum with the engine idling in gear. This will tell you which size power
valve to use. If your vacuum is 9" and under divide by two, and that is
the size you need. If it is 10" and over use a 6.5 PV. If the carb
backfired. If it did it probably blew out the power valve, Unless the carb
is 6 years
or newer and has power valve blowout protection. You will have to replace
it with the correct size. If you get all of this corrected and the car
still
runs rich then you will probably have to remove the carb and adjust the
secondary throttle plates open to the bottom of the transfer slots. This
will allow you to close the primary plates down some. If either plates are
open too far then fuel will be pulled in to the engine from the transfer
slots in the base plate. By adjusting those plates like I said, the carb
will get the same amount of air at idle, but it will get it evenly from
the
front and rear instead of just the front. Once you get it so the engine
dies with the idle air screws, then you can continue with the rest if the
adjustments. Next you need to adjust the idle air screws. Turn them in
until they seat lightly then back them out 1.5 turns. Start the car and
let it warm up. Hook up the vacuum gauge to manifold vacuum. Check it at
idle in gear. Adjust the idle air screws evenly until you get max vacuum
(the vacuum will drop off if you go to rich or lean) With that done you
can start working with your jetting Unfortunately I can't tell you how to
jet it. Each engine is different and has different requirements. It is a
trial and error process. The only thing you can do is adjust them until
you get
decent drillability, and then read the spark plug color to find out which
way you need to go. Black is rich and white is lean. Adjust it until you
get a nice light brown color on the porcelain of the plug. when you get
this adjusted . If you have a off line hesitation that is less than a
second Increase the shooter by one size. If it is over a second increase
the shooter by Two. If it makes the hesitation better you can increase
accordingly if it gets worse drop the size.
Thanks Tom
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