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350 idle

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redsnapper386

Regular Contributor
"guy's,i keep having this

"guy's,i keep having this idle problem.1987 5.7 350,260 h.p.4-bbl,quad jet.i have tried 2-different carbs.example,idle is set at 700 rpm,when i get under way,and come back to neutral,the idle will fluxuate down to 500 or up to 1000.fuel pump is good,5-7.timing ign all good.carb sqirts good cold & hot.torque on manifold is good.what to do ,thanks larry."
 
I bet your controll cable is l

I bet your controll cable is loose at the carb.

You need to make sure that there is POSITIVE pressure on the carb linkage from the cable so it returns always to the same spot. THEN adjust the idle speed to spec!

Remove the cable at the carb and adjust the trunion to accomplish this.
 
"Here is a drawing see if this

"Here is a drawing see if this helps.......Bored at work today!!


286397.jpg
"
 
"i have an '81 formula 233

"i have an '81 formula 233 thunderbird w/ a newer 350 mag alpha ('98 i think). it has a weber 4 barrel carb w/ the older (non-electric) choke and a TB IV ign. with the cold-start activated(manually closing choke plate w/my hand) and several pumps of throttle it will start immediately, then cut out. it takes 2-3 minutes of continuous cranking to get it started again. once warmed up, way less problems. i've eliminated all fuel possibilities and wouldn't be asking for help if i had the time (boat's in manasquan, nj and i'm in baltimore). it's embarassing to ask for help, but i could use some input from anyone who has experienced similar problems from their mcm 350 w/ a weber 4 barrel...bad grounds??? coil/dist./main harness??"
 
"jame's,so far my problem

"jame's,so far my problem is the fuel pump.get a fuel pump test gauge,and test your's.should be 5-7 psi.mine was not supplying enough fuel for a good idle.hope this helps."
 
""manually closing choke p

""manually closing choke plate w/my hand"

On a cold engine set the choke in the start position. It should be nearly closed. If not loosen the three screws holding the choke coil in place. Rotate the choke assy. until the choke plate barely closes. I hold a 1/8" drill bit in the way when turning the choke coil. PLACE 1' OF STRING ON THE DRILL BIT. Squirt some light oil or WD-40 on the ends of the choke plate so it moves easy.

While it is warming up the choke plate should open slowly. If it does not, feel the little tubes under the choke that enter the manifold; they should be warm to hot. If not then the intake passage may need cleaning due to blockage.

I would convert the stove pipe choke to an electric one."
 
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