Awkward....
Fast idle
Thread Starter
Safety Car
Joined: Jan 2004
Posts: 4,549
Likes: 343
From: Glastonbury CT
Fast idle
When starting carburetor went into fast idle about 3000 rpm and it would not drop the rpm even when hitting accelerator gingerly. I turned fast idle in with carburetor on car and car off in till it bottom out and then turned out two turns. Started car rpm went to 4500. How can this be corrected?
Is my vette stock?? HAHA
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Is it an electric choke or divorced choke. Im asking because the electric choke will stay on with no electricity, does the flap stay shut as well?. If you try unscrewing it until it isnt touching but doesnt fall out will the rpm drop? Check your vacuum lines as well to make sure you dont have a vacuum leak
Last edited by Rescue Rogers; Aug 6, 2021 at 03:33 PM.
Thread Starter
Safety Car
Joined: Jan 2004
Posts: 4,549
Likes: 343
From: Glastonbury CT
It starts will idle at specifications but slowly the rpm starts creeping to a higher rpm..What hell is doing this? History this is a Carb i rebuilt. . My original carb i rebuilt was not getting any fuel to the carb. ( Bad new China filter in carb) Just found this out when i needed back up because of the high rpm problem.
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again, turn the fast idle speed screw counter clockwise until it is around 1,500 rpm.
never heard of your method of turning it clockwise all the way in and then out two turns, that sounds like the instructions for an idle mixture screw.
never heard of your method of turning it clockwise all the way in and then out two turns, that sounds like the instructions for an idle mixture screw.
Safety Car
Joined: Oct 2007
Posts: 4,340
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From: Seattle Area Washington
The best off engine instructions I have found are in the Instructional Sheet #50-505-3.
Starting at Fig.5 the off engine choke setup says, Back off fast idle screw.
Cam follower set on the high position of fast idle cam.
Turn fast idle screw in until it contacts the stop on the cam follower lever.
Turn in fast idle screw 3 additional turns.
I find the 3 additional turns in on a cold start the RPMS are way too fast.
On my 17057204 the sweet spot is 1.5 turns in and the cold start RPMS are 1150-1200.
Rochester Instructional Sheet #50-505-3
LINK:https://www.carburetor-parts.com/***...s/50-505-3.pdf
Starting at Fig.5 the off engine choke setup says, Back off fast idle screw.
Cam follower set on the high position of fast idle cam.
Turn fast idle screw in until it contacts the stop on the cam follower lever.
Turn in fast idle screw 3 additional turns.
I find the 3 additional turns in on a cold start the RPMS are way too fast.
On my 17057204 the sweet spot is 1.5 turns in and the cold start RPMS are 1150-1200.
Rochester Instructional Sheet #50-505-3
LINK:https://www.carburetor-parts.com/***...s/50-505-3.pdf
Last edited by bmotojoe; Aug 7, 2021 at 02:28 PM.
Team Owner
Joined: Jan 2006
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From: Crossville TN
Make certain that the throttle cable and the carb linkage are all the way to a 'closed' throttle state when the engine is not running. It may just need an adjustment at the linkage or cable connection (rather than at the idle speed screw).
Thread Starter
Safety Car
Joined: Jan 2004
Posts: 4,549
Likes: 343
From: Glastonbury CT
I have the 17055704 carb and bmotojoe is correct off the car the two turns out did start the car after feeling no resistance i back it out. But what was the surprise was the fast idle i had ,do not like racing an engine on start up. As far as Melwff he was correct also but car was racing so fast i could not get to screw in the lower edge of carb fast enough to idle it down. So thanks to all above for your inputs..I am sure i will have other problems. I just have two many cars i manage and all different makes.