Go Back   Corvette Forum > C3 Corvettes, 1968 - 1982 > C3 Tech/Performance
Sign in using an external account
Register Forgot Password?
Register Search Today's Posts Mark Forums Read FAQ Vendor Directory
Search
C3 Tech/Performance
V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette Sponsored by
VBP

Welcome to Corvetteforum.com!
Welcome to Corvetteforum.com.

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 Corvetteforum.com today!


Corvette Store
 
 
C7 Parts & Accessories
C6 Parts & Accessories
C5 Parts & Accessories
C4 Parts & Accessories
C3 Parts & Accessories
C2 Parts & Accessories
C1 Parts & Accessories
Wheels & Tires
Sponsored Ads
 
 
Vendor Directory
  
Reply
 
 
 
 
Thread Tools Search this Thread
Old 08-19-2002, 05:40 PM   #1
467-Ratman
CF Senior Member
 
467-Ratman's Avatar
 
Member Since: Aug 2001
Location: Bay City MI.
Default 4 corner idle carbs?

I talked to the owner at custom rebuilt carbs.com and he was telling me about a Holley 850dp with mechanical secondaries and 4 corner idle circut. Anybody have one of these, and would it be a pain to tune? He told me that with my 467 motor and Crane 296 cam it would be a good choice for smoother idle and be awesome for WOT! Thanks!
467-Ratman is offline   Reply With Quote
Old 08-19-2002, 05:48 PM   #2
69 N.O.X. RATT
CF Senior Member
 
69 N.O.X. RATT's Avatar
 
Member Since: Aug 2001
Location: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Default Re: 4 corner idle carbs? (467-Ratman)

I have one of those carbs with annular discharge nozzles. I have a stout solid roller cammed 454 and it is a very good carb for my motor. If you have basic tuning skills it is not to much of a pain in the butt.
69 N.O.X. RATT is offline   Reply With Quote
Old 08-19-2002, 06:00 PM   #3
467-Ratman
CF Senior Member
 
467-Ratman's Avatar
 
Member Since: Aug 2001
Location: Bay City MI.
Default Re: 4 corner idle carbs? (69 N.O.X. RATT)

69 RATT, What size jets are you running, and does the carb ever foul the plugs? I am really wanting to go with the mechanical secondaries and the 4 corner idle sounds good to me. My cam is hydraulic, crane 296-2 lift is 551 and 571 with duration at 50 thousands 243 and 250. I have merlin rec port heads with 119cc combustion chambers and 310cc intake runners. Thanks for the input!
467-Ratman is offline   Reply With Quote
Old 08-19-2002, 07:18 PM   #4
69 N.O.X. RATT
CF Senior Member
 
69 N.O.X. RATT's Avatar
 
Member Since: Aug 2001
Location: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Default Re: 4 corner idle carbs? (467-Ratman)

To be honest I forget the jet sizes, besides it does not mean it would be the right one for your motor anyway. The carb does not foul the plugs if it is tuned right. Mechanical secondarys are very streetable, if tuned right. I would start with the stock jet sizes and keep an eye on the plugs and adjust accordingly. The hardest part for me is tuning the idle A/F mixture. make very slow turns on the adjustment and take your time. I have a problem with my car heating up the carb and fuel then the car does not want to idle, makes it difficult to adjust it then.
69 N.O.X. RATT is offline   Reply With Quote
Old 08-19-2002, 08:50 PM   #5
Chuck Harmon
CF Senior Member
 
Chuck Harmon's Avatar
 
Member Since: Apr 2000
Location: San Jose California
Default Re: 4 corner idle carbs? (467-Ratman)

I'm running a Holley 950dp from Holley's pro shop. The 4 corner idle adjustment really helps the L88 behave much better at idle. I heartily endorse it! The L88 cam measures in the mid 270's at .050", about 360 degrees at the seat.

Chuck
Chuck Harmon is offline   Reply With Quote
Old 08-19-2002, 09:05 PM   #6
Les
CF Senior Member
 
Les's Avatar
 
Member Since: Dec 1999
Location: Sierra Foothills CA
Default Re: 4 corner idle carbs? (Chuck Harmon)

Another vote for 4 corner idle. My Barry Grant modded Holley DP idles right after start-up and it has no choke. It also delivered a .35 reduction in my 1/4 mile ET. Probably the best single part I've put on the motor.
Les is offline   Reply With Quote
Old 08-19-2002, 09:07 PM   #7
QuickVet
CF Senior Member
 
QuickVet's Avatar
 
Member Since: Feb 2000
Location: www.corvettechallenge.info
Default Re: 4 corner idle carbs? (Les)

i have a four corner idle carb. kicks butt. idle was much better then with other carbs. :yesnod:
QuickVet is offline   Reply With Quote
Old 08-19-2002, 09:17 PM   #8
467-Ratman
CF Senior Member
 
467-Ratman's Avatar
 
Member Since: Aug 2001
Location: Bay City MI.
Default Re: 4 corner idle carbs? (QuickVet)

Thanks all for the info, I know for sure that this old 780 is out of here soon. The idle really sucks and the cam is not that wild, 550 and 570 lift and 236 and 246 duration at .050 lift. Can't wait to enjoy the extra power that the 850 and mechanical secondaries will give me. Anybody wants this carb let me know!
467-Ratman is offline   Reply With Quote
Old 08-20-2002, 08:40 AM   #9
norvalwilhelm
CF Senior Member
 
norvalwilhelm's Avatar
 
Member Since: Nov 2000
Location: Waterloo ontario Canada
Default Re: 4 corner idle carbs? (467-Ratman)

I have 2 of them on my bigblock. All double pumpers run richer because they are more performance oriented. The problem I find is the idle circuit. It is way too rich. I always drill about .100-.125 holes in the throttle plates but only the plates with it's own idle circuit so in this case all 4. The placement of these holes is critical. I also lean out the idle mixture with .015 wire struck in the 4 idle circuit metered holes. The main jets are 80 stock all around and you can run these IF you lean out the idle circuit. The idle circuit, the transfer slots and the main jets control the cruising mixture. To do just the main jets leaves the idle mixture too rich. Work on the idle mixture and the cruising circuit will look after itself.
I run 2 of these carbs and still get 12 mpg around town.
Click the image to open in full size.
norvalwilhelm is offline   Reply With Quote
Old 08-22-2002, 12:54 PM   #10
467-Ratman
CF Senior Member
 
467-Ratman's Avatar
 
Member Since: Aug 2001
Location: Bay City MI.
Default Re: 4 corner idle carbs? (467-Ratman)

Looks like I am going to get the 4 corner idle carb for my car, I have tried adjusting my Holley 780 and the car will not idle until it reaches about 180 degrees. My hot air choke seems to be working fine, but the car just dies if I am not working the throttle. The idle is about 1100 rpms.I have checked for vacuum leaks and dont seem to find any. I have drilled my throttle plates and have the adjusting screws for the idle circut turned out about 3 turns. Can I make this carb work with my motor, or should I forget it and buy the Holley 850 dp 4 corner?
467-Ratman is offline   Reply With Quote
Old 08-22-2002, 01:01 PM   #11
Fevre
CF Senior Member
 
Fevre's Avatar
 
Member Since: Mar 2001
Location: Living the Surreal Life in Ypsitucky MI
Default Re: 4 corner idle carbs? (467-Ratman)

Hate to say it but i think you will have a harder time with that dp than with that avenger. Anyone you know that might be able to take a look at it for you? Sounds like your choke isn't set right.
Fevre is offline   Reply With Quote
Old 08-22-2002, 01:11 PM   #12
467-Ratman
CF Senior Member
 
467-Ratman's Avatar
 
Member Since: Aug 2001
Location: Bay City MI.
Default Re: 4 corner idle carbs? (Fevre)

When you watch the choke operate with the air cleaner off, it seems to open properly, but it does take a long time to open fully. Untill it heats up the space that it opens looks small , if you try to flip it open more it dies for sure. do I need more fuel with the idle circut to keep the motor running?
467-Ratman is offline   Reply With Quote
Old 08-22-2002, 01:51 PM   #13
Fevre
CF Senior Member
 
Fevre's Avatar
 
Member Since: Mar 2001
Location: Living the Surreal Life in Ypsitucky MI
Default Re: 4 corner idle carbs? (467-Ratman)

Don't get me wrong I think with your set up the 850 dp would rock but it has a lot more things to adjust than the avenger carb. There should be a way to adjust to choke richer. I have an electric choke and am not familiar with the hot air type but if it dies when you open it then I would say it is lean.
Fevre is offline   Reply With Quote
Old 08-22-2002, 04:53 PM   #14
467-Ratman
CF Senior Member
 
467-Ratman's Avatar
 
Member Since: Aug 2001
Location: Bay City MI.
Default Re: 4 corner idle carbs? (Fevre)

At lunch time I adjusted the choke arm, made it straigher making the choke close a little farther, seems to have helped. I am also going to adjust the idle circut screws tonight and make it a little richer. Thanks for the suggestions!
467-Ratman is offline   Reply With Quote
Old 08-22-2002, 04:57 PM   #15
Fevre
CF Senior Member
 
Fevre's Avatar
 
Member Since: Mar 2001
Location: Living the Surreal Life in Ypsitucky MI
Default Re: 4 corner idle carbs? (467-Ratman)

No problem. Too bad you don't live closer I would let you try out my 750 dp just to see if you like the mech sec. I am going to rebuild it this weekend and to try on my little 350. Overkill for sure but might be good for the track once in a while. I plan on doing a 383 in the next few years so it should be better for that project.

BTW Although the choke tower is no go for performance, it is nice to have for warming up the car.


[Modified by Fevre, 2:58 PM 8/22/2002]
Fevre is offline   Reply With Quote
Old 08-22-2002, 09:58 PM   #16
467-Ratman
CF Senior Member
 
467-Ratman's Avatar
 
Member Since: Aug 2001
Location: Bay City MI.
Default Re: 4 corner idle carbs? (Fevre)

Fevre, Keep me posted on how you like the 750dp on your 350 motor. Last year I had my 350 with an LT-1 intake and solid lifter cam, and my holley 780 carb, you will like the 750 dp on that motor, big fun!!!
467-Ratman is offline   Reply With Quote
Old 08-22-2002, 09:58 PM
 
Go Back   Corvette Forum > C3 Corvettes, 1968 - 1982 > C3 Tech/Performance
Reload this Page 4 corner idle carbs?
 
 
 
Reply

Tags
4corner, 950, adjust, adjusting, adjustment, carb, circuit, corner, double, holley, idle, lean, pumper, rich, tune, tuning


Thread Tools Search this Thread
Search this Thread:

Click for 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
F/S Holley 850DP 4 corner idle 467-Ratman C3 Parts for Sale/Wanted 1 05-07-2004 05:19 PM
Jet size for 850dp 467-Ratman C3 Tech/Performance 16 09-23-2002 10:34 AM
Holley carb ID help 467-Ratman C3 Tech/Performance 2 09-17-2002 02:32 AM
Do I need a choke on 850dp? 467-Ratman C3 Tech/Performance 8 08-28-2002 06:11 PM
Holley 850dp or Demon 850? 467-Ratman C3 Tech/Performance 5 08-25-2002 04:36 PM


All times are GMT -4. The time now is 03:50 AM.


Emails & Password Backup