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Carburator Fast Idel adjustment on a 4300 4BBL

494 Views 2 Replies 3 Participants Last post by  dcudmore
Does anyone know the best way to tune a 4300 carb?
I have this problem w/ my fast idle upon like a banshee.... have to manually kick it down w/ a pen or open the butterfly.
Also what is the best way to get rid of flat spots...that occur during cruising/maintaining speed(as in not accelerating)?
Any tips..pointers etc. much appreciated.
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you need a professional carb guy for the flat spots.
"pony carburators" located in ny say they can do this.
the high reving thing used to happen to mine, i just lubed the heck out of the linkage, got off all the crude, and it was better,
maybe i got lucky.
hope you do too.
let us know
I have a 4300 on the 69, 351W. I rebuilt it and had some problems getting it to run right as well. My first mistake was that I had the electric choke control one turn out.This slowed the idle down a great deal. There is a fast idle screw below the choke as well that sort of governs it.
On the settings I turned out both screws 1 1/2 turns to start that then would try in out. Let the engine get to operating temp and check the distance between the throttle body and the choke plate in the carb.There should be about 1/4 inch there.If there isn't then loosen the electric choke cover and turn the choke until you have about that distance, Try it on the road again and see if that helps. The carb adjustment I would just turn anti clockwise about 1/4 turn at a time , both screws. Then take it for a ride and if you like adjust it as you go.If it gets worse instead of better turn the scews clockwise from the 1 1/2 turn startup. This is probably not the true blue method but it worked for me and yesterday on a 300 mile trip to the show I averaged 20 mile to the gallon with my 351 W 4V so I am deffinetly happy with that.
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