Holley 850 DP idle mixture screws
Thread Starter
Safety Car
Joined: Jul 2002
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From: St Louis MO
Holley 850 DP idle mixture screws
I added a Holley secondary idle adjustment screw to my 850. This allows me to adjust the secondary idle from the top of the carb, without having to pull it off and adjust it from the bottom. Also, I put some clear sight plugs on the bowls. Anyway, I was re-tuning it tonite and noticed I can screw the primary idle mixture screws all the way in and the motor won't die. Actually, it idles better the farther in they are. This doesn't sound right to me. What gives? I can screw the secondary idle mixers in all the way and the motor immediately dies. Back in the summer, I added the wires in the idle passages to lean it out. Been running fine until I noticed this little jewel of a problem.
Brett :thumbs:
Brett :thumbs:
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From: Waterloo ontario Canada
Re: Holley 850 DP idle mixture screws (Brettmc)
Want to comment on the clear site plugs. They are a disaster waiting to happen. The head can break off when you least expect it and gas can pour out causing a fire if you don't notice it. I would stick with the brass stock ones.
Thread Starter
Safety Car
Joined: Jul 2002
Posts: 3,770
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From: St Louis MO
Re: Holley 850 DP idle mixture screws (norvalwilhelm)
Want to comment on the clear site plugs. They are a disaster waiting to happen. The head can break off when you least expect it and gas can pour out causing a fire if you don't notice it. I would stick with the brass stock ones.
Brett :thumbs:
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From: delmont pa
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Re: Holley 850 DP idle mixture screws (Brettmc)
you may have the pri butterflys open too far and you are pulling fuel from the idle transfer slots.
I added a Holley secondary idle adjustment screw to my 850. This allows me to adjust the secondary idle from the top of the carb, without having to pull it off and adjust it from the bottom. Also, I put some clear sight plugs on the bowls. Anyway, I was re-tuning it tonite and noticed I can screw the primary idle mixture screws all the way in and the motor won't die. Actually, it idles better the farther in they are. This doesn't sound right to me. What gives? I can screw the secondary idle mixers in all the way and the motor immediately dies. Back in the summer, I added the wires in the idle passages to lean it out. Been running fine until I noticed this little jewel of a problem.
Brett :thumbs:
Brett :thumbs:
Thread Starter
Safety Car
Joined: Jul 2002
Posts: 3,770
Likes: 3
From: St Louis MO
Re: Holley 850 DP idle mixture screws (clem zahrobsky)
Before I put the carb back on, I adjusted the idle screws until I had just a small small small part of the slots showing. I had to back off the idle after firing it up. I adjusted the pri and sec the same amount, or real close to the same amount. So I doubt there is any slot showing at all now. Good idea tho.
Brett :thumbs:
Brett :thumbs:
Thread Starter
Safety Car
Joined: Jul 2002
Posts: 3,770
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From: St Louis MO
Re: Holley 850 DP idle mixture screws (Brettmc)
Anybody else??
With the primary idle mixers out 1 turn, there's 14" of vacuum at idle. With them in all the way, there's 16" of vacuum.
Brett :thumbs:
[Modified by Brettmc, 12:20 AM 1/23/2004]
With the primary idle mixers out 1 turn, there's 14" of vacuum at idle. With them in all the way, there's 16" of vacuum.
Brett :thumbs:
[Modified by Brettmc, 12:20 AM 1/23/2004]
Race Director
Joined: Aug 2000
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From: HONOLULU HAWAII
Re: Holley 850 DP idle mixture screws (Brettmc)
Want to comment on the clear site plugs. They are a disaster waiting to happen. The head can break off when you least expect it and gas can pour out causing a fire if you don't notice it. I would stick with the brass stock ones.
:eek: No feces?!?! That would mean the gas weakens the material, right?
Brett :thumbs:
:eek: No feces?!?! That would mean the gas weakens the material, right?
Brett :thumbs:
Yep.....No Feces......I had them plastic wonders on my Hardcore 900XP Dominator when it arrived mounted on top of my new Bill Mitchell Small Block 427 ci Crate Engine. Went to set the float levels because both plastic windows turned white from gas.....When I tried to unscrew the plastic windows....they broke off at the head....leaving the stud part stuck inside the bowls....when I tried to remove the stud parts the threads were damaged....Had to mount my Hardcore 870 to get the engine running and have the bowls on the 900XP re-tapped.....Now they have the metal plugs.. :smash: There are many more out there who have suffered the same problem with plastic plugs.... :steering:
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From: Waterloo ontario Canada
Re: Holley 850 DP idle mixture screws (redvetracr)
Ask carb guru Lars and post his answer!! ...redvetracr
Why do we have to ask Lars about a problem that alot of us have had with those clear plastic plugs. They are junk and that's all there is too it.
Why do we have to ask Lars about a problem that alot of us have had with those clear plastic plugs. They are junk and that's all there is too it.
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Re: Holley 850 DP idle mixture screws (norvalwilhelm)
I don't understand the 4 corner idle either, I can turn some in out and no change then I turn one ( secondary drivers side ) a little and it makes a huge difference.
I got it idling OK and gave up. I wish someone (that has actuallly done it right ) would post the proper proceedure for dialing in the idle mixture with all four screws. :confused:
I got it idling OK and gave up. I wish someone (that has actuallly done it right ) would post the proper proceedure for dialing in the idle mixture with all four screws. :confused:
