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i have a weird problem with an 87 phazer with a 480 f/c. the sled will idle great but have a slight bog and it will go away when you engage the choke and richen the mixture. i have cleaned these carbs numerous times. It will also act funny a lot and is untuneable. the changes are so fast i was thinking maybe spark...it has spark at all times so maybe it's weak? stator or cdi unit? I did compressions and a leakdown test and all seals are holding pressure.
any suggestions?
thanks
Brian A. Pekarek
 

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Check your main needle valves (the rubber plungers that stop the fuel from filling the carb), Mine had a similar problem, it was the right side needle stuck open with a spec of dirt, you could only tell something was wrong with it at idle. You could also check your air idle setting.
 

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The idle jets on the older Phazer normally have to be set richer than optimum at idle to prevent the bog at takeoff.
 

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Originally posted by PZ1
[br]The idle jets on the older Phazer normally have to be set richer than optimum at idle to prevent the bog at takeoff.
what size jets would you recommend if it is piped
 

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Originally posted by aspencer
[br]
Originally posted by PZ1
[br]The idle jets on the older Phazer normally have to be set richer than optimum at idle to prevent the bog at takeoff.
what size jets would you recommend if it is piped
They are the screws on top of the carbs. Run the engine at the recommended idle RPM and turn on the screws until the engine idles the best. Go back and forth on the screws, set one then the other, then go back to the first, doing this several times and readjusting the idle speed as necessary. They both should end up about the same number of turns out. Run the sled. If you have a bog, turn each screw out one eighth turn and try again. Continue this until the bog is gone. Temperature will make a difference. When it is cold out, you may have to readjust.
Another thing that would cause it is a vacuum leak or a crank seal
leak.

The engine should be fully warmed up when the carbs are set.
 
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