Author Topic: 4 corner idle screws  (Read 1121 times)

Offline dodj

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4 corner idle screws
« on: September 26, 2015 - 01:23:24 PM »
Hi All
I have a question regarding the four corner idle screws on my Quickfuel BD850. The Quickfuel site says you can keep all four adjusted the same, or...not. Experiment to find what works best.
What do you guys with four corner idle adjustment do? Keep them all the same or not? Or does it really matter so long as you get it to idle well?
Scott
1973 Challenger  440 4 spd 
2007.5 3500 6.7 Cummins Diesel, Anarchy tuned.
Good friends don't let friends do stupid things. ........alone.




Offline TelisSE440

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Re: 4 corner idle screws
« Reply #1 on: September 26, 2015 - 01:50:25 PM »
Dodj, I have used the following video to adjust my Holley 950 cfm. Yours is a QuickFuel, but I think is the same construction. Anyway, all four idle screws need the same adjustment, that's what I saw in my engine with the vacuum gauge...

https://www.youtube.com/watch?v=UPGLUsW5ZeE

Offline cudabob496

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Re: 4 corner idle screws
« Reply #2 on: September 26, 2015 - 07:07:40 PM »
start out all at 3/4 open, and go from there
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000

Offline Chryco Psycho

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Re: 4 corner idle screws
« Reply #3 on: September 26, 2015 - 11:59:09 PM »
it depends if the throttle plates are opened equally , if they are all opened up equally the the idle screws should be close to equal too , if the primary throttle plates are opened more the idle screws will need to be opened a bit more to match the extra airflow

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Offline cudabob496

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Re: 4 corner idle screws
« Reply #4 on: September 27, 2015 - 04:12:19 AM »
how radical is your cam, and what is your engine size?
I could not get a decent idle until I put holes in throttle plates.
Now the new carbs have an extra adjustment so the holes are not necessary.
Called the integrated idle bypass adjustment valve I think.
« Last Edit: September 27, 2015 - 04:17:48 AM by cudabob496 »
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

2011 Kawasaki Z1000