Engine has trouble idling down
#1
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Engine has trouble idling down
Have a mild build 350 in my boat and sometimes (most times) it has a hard time idling down. Sometimes I have to shut it off and restart a few times to get it down to a reasonably safe shift rpm. Engine has LT4 hot cam, 650 demon with electric choke, v6-14 ignition module. Base timing is set around 22 degrees. Could the choke linkage be hanging or maybe to much timing? I've killed 2 drives in the last year and I'd like to get the idle down to about 650. Also, the idle screw adjustment on the throttle linkage is backed all the way off
#2
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possible throttle cable problem so unhook the cable and work the throttle by hand blipping it and see if idle returns how it should ?
Also check for resistance in the throttle plate shaft possible bent or stuck or corrosion issues
also adjustment on carb out of spec for your app
also a vacuum leak somewhere at base of carb or intake
Also check timing
make sure your distributor can not rotate - check hold down clamp
Also check for resistance in the throttle plate shaft possible bent or stuck or corrosion issues
also adjustment on carb out of spec for your app
also a vacuum leak somewhere at base of carb or intake
Also check timing
make sure your distributor can not rotate - check hold down clamp
Last edited by BUP; 07-31-2015 at 09:24 PM.
#3
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87 Magnum - is this right after running WOT ?
Most BG vacum secondary carbs, especially with lighter vac secondary springs, will do this.
The trick; shift to neutral, shut off engine and restart....idle should go back to normal.
You will kill an Alfalfa almost instantly with too high rpm shifting into gear.
Most BG vacum secondary carbs, especially with lighter vac secondary springs, will do this.
The trick; shift to neutral, shut off engine and restart....idle should go back to normal.
You will kill an Alfalfa almost instantly with too high rpm shifting into gear.
Last edited by SB; 07-31-2015 at 09:43 PM.
#4
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BTW: choke has nothing to do with it as I remove the chokes from most all carbs and these will still do it.
#7
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#8
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Hey guys I got this one...Lol. Sounds funny, but Yes, I'm serious.
The secondary spring doesn't have enough tension to close off the secondaries with air running thru it. Shutting off the engine, stops the airflow. The low tension spring can now close the secondary throttle shaft.
I run into same issues with some throttle bodies with weak throttle shaft springs. And this make carburetor.
The secondary spring doesn't have enough tension to close off the secondaries with air running thru it. Shutting off the engine, stops the airflow. The low tension spring can now close the secondary throttle shaft.
I run into same issues with some throttle bodies with weak throttle shaft springs. And this make carburetor.
#9
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^^^^^ exactly and the reason I said to unhook the throttle cable - that will tell you right away if your cable is out of adjustment or bad / needing replacement - the boat is an 1987 is this original throttle cable ? 19897 very possible throttle cable problem
post 7 - I am referring to.
Also when is your high idle ?
post 7 - I am referring to.
Also when is your high idle ?
Last edited by BUP; 07-31-2015 at 09:43 PM.