Search



Go Back   Third Generation F-Body Message Boards > Tech Boards > Carburetors
Register Forgot Password?

Carburetors Carb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.

Welcome to ThirdGen.org!
Welcome to ThirdGen.org.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!


Reply
 
Thread Tools Search this Thread
Old 04-02-2007, 08:50 PM   #1
Moderator
 
Air_Adam's Avatar
 
Join Date: Oct 2002
Location: Saskatoon, SK, Canada
Posts: 9,067
Car: '83 Z28, '07 Charger SRT8
Engine: 454ci, 6.1 Hemi
Transmission: TH350, A5
Axle/Gears: 2.73 posi, 3.06 posi

Classifieds Rating: (0)

Send a message via MSN to Air_Adam
Primary Idle VS 4-Corner Idle?

Hey guys,

Just a question... I've never really done much tuning on 4-corner idle carbs, but have recently got a 750 DP Holley (4779).

I know how to tune the idle on a primary idle Holley (where only the primary metering block has adjustment screws) as I've got a 750 VS 3310 and a 650 DP 4777 like this.

How does tuning the 4-corner idle carb differ from the other two I've had? I do have a vacuum guage, which helps, but I'm just not familiar with how the 4-corner system works... do all 4 idle screws have to be set the same? Do all 4 throttle blades have to be opened the same amount at idle speed? This is the kind of thing I'd like to know.

This is on a 350 4-spd manual car by the way.
__________________
Quote:
Originally Posted by Everyone I Know
"Man, did you see it leave!? It left hard and then all that s**t blew up!"
Air_Adam is offline vBGarage Page   Reply With Quote
Old 04-02-2007, 11:15 PM   #2
Moderator
 
five7kid's Avatar
 
Join Date: Mar 2000
Location: Littleton, CO USA
Posts: 42,050
Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 10B-3.73/9"-3.89

Classifieds Rating: (14)

Well, they all have idle in the secondaries as well. The difference is you can't adjust the secondary idle mixture on the typical universal carb.

I can't give you much more detail than that, but you just add the secondary adjustment to the mix. Especially helps if you have a lumpy cam.
five7kid is offline vBGarage Page   Reply With Quote
Old 04-03-2007, 02:50 AM   #3
Supreme Member
 
xpndbl3's Avatar
 
Join Date: Jan 2002
Location: Orland Park, IL
Posts: 13,582
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11

Classifieds Rating: (5)

Send a message via AIM to xpndbl3
Re: Primary Idle VS 4-Corner Idle?

the transition slots and mixture screws should all be at the same opening, but I've had it before on some intakes were 1/8 turn more for the primary or secondaries smoothed out the idle much more, probably a fuel distribution issue.
__________________
How fast is it? That depends on who's around
2011 chicago world of wheels placed in super street class
Best Engine '11 Thirdgenfest
Best Modified Camaro Thirdgenfest '05, '07, '11 Second place Camaro Modified '06, '08, '10, & '12
MFBA March 2008 Featured Calendar Vehicle

Last edited by xpndbl3; 04-04-2007 at 09:46 PM.
xpndbl3 is offline vBGarage Page   Reply With Quote
Old 04-03-2007, 07:08 PM   #4
Moderator
 
Air_Adam's Avatar
 
Join Date: Oct 2002
Location: Saskatoon, SK, Canada
Posts: 9,067
Car: '83 Z28, '07 Charger SRT8
Engine: 454ci, 6.1 Hemi
Transmission: TH350, A5
Axle/Gears: 2.73 posi, 3.06 posi

Classifieds Rating: (0)

Send a message via MSN to Air_Adam
Re: Primary Idle VS 4-Corner Idle?

Do all 4 throttle blades have to be open the same? Or can I just use the primary idle speed screw to adjust idle speed? Whats a good starting point to set the mixture screws to, to start out with? I used 1.5 turns on my old carbs, does that work for this one as well?
Air_Adam is offline vBGarage Page   Reply With Quote
Old 04-04-2007, 02:32 AM   #5
Supreme Member
 
xpndbl3's Avatar
 
Join Date: Jan 2002
Location: Orland Park, IL
Posts: 13,582
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11

Classifieds Rating: (5)

Send a message via AIM to xpndbl3
Re: Primary Idle VS 4-Corner Idle?

depending on how much air your motor needs, all 4 should be open the same. Now if it idles really low in the rpm range the the rears can be closed off IIRC. With all the motors I've used 4 corner systems on, they all needed 1000 out of gear and 800-900 in gear so all 4 slots have been even. I'm sure a milder combo wouldn't need that much slot open. You can start at 1 turn out and tune from there, honestly as long as the motor runs at idle when warmed up you can go in or out with the screws to find the best vacuum in gear for an automatic or out of gear for a stick.

Also I don't have all the answers, only what I've picked up along the way, hopefully someone with more tuning experience can chime in, but this is what has worked for me at least Seems lately whenever I post to help out I'm shot down and told not to post "if I don't know what I'm talking about" so maybe that's the way this site is headed. I'm not really sure.
__________________
How fast is it? That depends on who's around
2011 chicago world of wheels placed in super street class
Best Engine '11 Thirdgenfest
Best Modified Camaro Thirdgenfest '05, '07, '11 Second place Camaro Modified '06, '08, '10, & '12
MFBA March 2008 Featured Calendar Vehicle
xpndbl3 is offline vBGarage Page   Reply With Quote
Old 04-04-2007, 07:26 PM   #6
Supreme Member
 
Sonix's Avatar
 
Join Date: Jul 2004
Location: Calgary, AB, Canada
Posts: 10,763
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73

Classifieds Rating: (1)
Re: Primary Idle VS 4-Corner Idle?

hey, hey! Who let xpndbl3 out of his cage?
Yea xpndbl3, just because you have a really fast, good looking car doesn't mean we should trust you

adam, you have the 10:1 350 with an xe274? Is the weather there good enough to take the car out yet?
I'm looking forward to track results out of your car, I should be able to finally get mine to the strip this summer and compare
Sonix is offline vBGarage Page   Reply With Quote
Old 04-04-2007, 11:00 PM   #7
Moderator
 
Air_Adam's Avatar
 
Join Date: Oct 2002
Location: Saskatoon, SK, Canada
Posts: 9,067
Car: '83 Z28, '07 Charger SRT8
Engine: 454ci, 6.1 Hemi
Transmission: TH350, A5
Axle/Gears: 2.73 posi, 3.06 posi

Classifieds Rating: (0)

Send a message via MSN to Air_Adam
Re: Primary Idle VS 4-Corner Idle?

Quote:
Originally Posted by Sonix View Post
hey, hey! Who let xpndbl3 out of his cage?
Yea xpndbl3, just because you have a really fast, good looking car doesn't mean we should trust you

adam, you have the 10:1 350 with an xe274? Is the weather there good enough to take the car out yet?
I'm looking forward to track results out of your car, I should be able to finally get mine to the strip this summer and compare
11:1 actually, and what do you mean 'taken out'? Its been out all winter being driven lol.
Air_Adam is offline vBGarage Page   Reply With Quote
Old 04-04-2007, 11:17 PM   #8
Supreme Member
 
xpndbl3's Avatar
 
Join Date: Jan 2002
Location: Orland Park, IL
Posts: 13,582
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11

Classifieds Rating: (5)

Send a message via AIM to xpndbl3
Re: Primary Idle VS 4-Corner Idle?

shhhh don't tell anyone that i'm out of my cage. Makes me laugh because I had some shots of me behind the rear bars of my cage while putting it in and everyone on the chicago board called it the gorilla locked in his car for a long time now.

PS Sonix, who ever said this car was fast It's a show car and I'm sticking to it.
xpndbl3 is offline vBGarage Page   Reply With Quote
Old 04-04-2007, 11:20 PM   #9
Member
 
urmomshot77's Avatar
 
Join Date: Dec 2006
Location: Nebraska
Posts: 117
Car: 83 camaro
Engine: 383 stroker
Transmission: TCI 3spd manual
Axle/Gears: 3.73

Classifieds Rating: (0)
Re: Primary Idle VS 4-Corner Idle?

Quote:
Originally Posted by Air_Adam View Post
Do all 4 throttle blades have to be open the same? Or can I just use the primary idle speed screw to adjust idle speed? Whats a good starting point to set the mixture screws to, to start out with? I used 1.5 turns on my old carbs, does that work for this one as well?
Well its been about mid 40s here this week and i have my quad idle screws turned out 1 1/4 turns, and its running good. The secondary adjustment screw is there as another way to tune your idle. However don't rely on it too much or you will actually open the secondary barrels to a point were your manifold vaccuum will start drawing fuel prematurely out of the secondaries.
urmomshot77 is offline vBGarage Page   Reply With Quote
Old 04-04-2007, 11:26 PM   #10
Supreme Member
 
xpndbl3's Avatar
 
Join Date: Jan 2002
Location: Orland Park, IL
Posts: 13,582
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11

Classifieds Rating: (5)

Send a message via AIM to xpndbl3
Re: Primary Idle VS 4-Corner Idle?

both the front and rear slots are the same length, and they both should be opened to the same slot size; so opening the rears up too much would have to be a 2500 idle easily before the boosters would see a signal and draw fuel out if the fronts and rears were open the same amount.
xpndbl3 is offline vBGarage Page   Reply With Quote
Old 04-05-2007, 12:49 AM   #11
Supreme Member
 
Sonix's Avatar
 
Join Date: Jul 2004
Location: Calgary, AB, Canada
Posts: 10,763
Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73

Classifieds Rating: (1)
Re: Primary Idle VS 4-Corner Idle?

Holy cow adam, you're a brave guy driving that thing in the winter. I couldn't even be able to get mine to drive forward in the cul-de-sac, took me 5 minutes to get across it, it's like trying to run on ice with duct tape on the bottom of your shoes- curling style. OUCH!
11:1 eh? Do you notice any knocking? When you lug it? Do you run less than ideal timing?

haha, I don't know Steve, a TH350, moser 9" and a full out cage ? I'd think it'd be a little fast. I mean, if it wasn't that fast i'd use a 700R4 and enjoy the overdrive, but if you're fast enough to break one of those...
Is the snow melted over in Illinois yet?

Yea, I have nothing useful to add to this thread, don't mind me.
Sonix is offline vBGarage Page   Reply With Quote
Old 04-05-2007, 01:17 AM   #12
Supreme Member
 
xpndbl3's Avatar
 
Join Date: Jan 2002
Location: Orland Park, IL
Posts: 13,582
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11

Classifieds Rating: (5)

Send a message via AIM to xpndbl3
Re: Primary Idle VS 4-Corner Idle?

Quote:
Originally Posted by Sonix View Post
haha, I don't know Steve, a TH350, moser 9" and a full out cage ? I'd think it'd be a little fast. I mean, if it wasn't that fast i'd use a 700R4 and enjoy the overdrive, but if you're fast enough to break one of those...
Is the snow melted over in Illinois yet?

Yea, I have nothing useful to add to this thread, don't mind me.
nah...the trans came out of IHI's car off this board, so you know that took off at least .4 in the quarter. Since he's flying wheels up all the time at the track. Well, there's no more snow here, well at least that sticks to the ground. Right now we had flurries today with a high of 32 and a low of 20. Sucks....it was 60s earlier this week, supposed to be 40 or below for the next 10 days off weather.com so I don't like working on my back finishing up the 9" install with the concrete being frozen still in the garage.
xpndbl3 is offline vBGarage Page   Reply With Quote
Old 04-05-2007, 10:28 PM   #13
Moderator
 
Air_Adam's Avatar
 
Join Date: Oct 2002
Location: Saskatoon, SK, Canada
Posts: 9,067
Car: '83 Z28, '07 Charger SRT8
Engine: 454ci, 6.1 Hemi
Transmission: TH350, A5
Axle/Gears: 2.73 posi, 3.06 posi

Classifieds Rating: (0)

Send a message via MSN to Air_Adam
Re: Primary Idle VS 4-Corner Idle?

Quote:
Originally Posted by Sonix View Post
Holy cow adam, you're a brave guy driving that thing in the winter. I couldn't even be able to get mine to drive forward in the cul-de-sac, took me 5 minutes to get across it, it's like trying to run on ice with duct tape on the bottom of your shoes- curling style. OUCH!
11:1 eh? Do you notice any knocking? When you lug it? Do you run less than ideal timing?

haha, I don't know Steve, a TH350, moser 9" and a full out cage ? I'd think it'd be a little fast. I mean, if it wasn't that fast i'd use a 700R4 and enjoy the overdrive, but if you're fast enough to break one of those...
Is the snow melted over in Illinois yet?

Yea, I have nothing useful to add to this thread, don't mind me.
Yea... the motor isn't very happy with pump premium lol. I had to keep the timing down to 8 inital, although its much happier around 16* idle except for the pinging lol. I have to run it a little bit rich at idle too when its really cold out, which doesn't help things much.

The pinging is actually not really a problem if you tune conservatively and don't get too heavy on the throttle if you are in too high a gear. I'm sure its got alot more in it though if I could tune it the way it wants to be run and use good fuel in it lol.

I'll be changing the heads for a set of 64cc heads though (have 55cc now), so it should knock it down to a more pump fuel friendly compression level.
Air_Adam is offline vBGarage Page   Reply With Quote
Old 04-05-2007, 10:28 PM
ThirdGen
1992 Camaro




Paid Advertisement


Reply

Go Back   Third Generation F-Body Message Boards > Tech Boards > Carburetors

Tags
4779, add, carb, corner, corneridle, front, holley, idel, idle, mixture, primaries, rear, screws, secondaries, set, system, tune
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92


All times are GMT -5. The time now is 12:06 AM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.5.2
All content copyright 1997 - 2014 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.

Emails & Contact Details