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 04-27-2003, 04:32 AM   #1
TIMSPEED
CF Senior Member
 
TIMSPEED's Avatar
 
Member Since: Mar 2001
Location: Modesto CA
Send a message via AIM to TIMSPEED Send a message via Yahoo to TIMSPEED
Default Holley 4160 Question: Stumble off Idle...?

Well friends, I'm having a bit of trouble getting my new motor dialed in. I'm running a:
355cid SBC
-9:1 Compression
-#882 Heads
-Stock Cam
-Edelbrock Performer Intake/Hedman 1 5/8 Long Tube Headers

Now, the only vacuum ports I'm using is: Manifold Vacuum (for distributor advance) and then the charcoal canister and PCV port. I had my friends dad look at my carb, and he got it all dialed in, but he said that it's leaking raw fuel into the intake, because when he turned my idle mixture screws all the way closed (lean), he said it was SUPPOSED to die..but it didn't (but the idle was REALLY rough). At first, he thought it was a vacuum leak, but we checked and I have a solid 20" at idle. What happens is, when I press the gas off idle, it basically stalls, THEN goes. Right now, the timing is at 14 advance @ 750rpm, and it still is running like crap. He said for me to get my carb rebuilt, but the carb is BRAND new. Any ideas? ANY help is appreciated! Thanks guys!
TIMSPEED is offline   Reply With Quote
Old 04-27-2003, 04:38 AM   #2
Corz
CF Senior Member
Cruise-In IV Veteran
 
Corz's Avatar
 
Member Since: Sep 2001
Location: Manchester Connecticut
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

honestly... throw the holley out. i had nothing but problems with it. I bought a demon and it works perfect. just adjust the mixture screws and it runs like a champ.
Corz is offline   Reply With Quote
Old 04-27-2003, 10:02 AM   #3
Matt Gruber
CF Senior Member
 
Member Since: Oct 2000
Location: New Smyrna Beach, FL
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

with a stock cam you need a holley 4165, which is a street replacement for the qjet. There are other choices, but not a stock 4160.
the 4160 is a race carb. it can be made to work; i'm sure everyone here will chime in on details if you are stubborn or can't afford a better carb. i've never used the 4160 'cause i've never owned a race only car.
.
EDIT Kudos to Wayne for picking up my mistake! i was thinking 4150 just like wayne said.
As a result, there will be no charge for my advice! LOL


[Modified by Matt Gruber, 9:19 AM 4/28/2003]
Matt Gruber is offline   Reply With Quote
Old 04-27-2003, 10:49 AM   #4
kraventhearcher
Junior Member
 
kraventhearcher's Avatar
 
Member Since: Mar 2003
Location: Boone NC
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

What are your jet sizes, accelerator pump part number, and float level settings.
Also, check the power valves for blow out. They may be leaking.
Check the accelerator pump for proper adjustment (zero lash), in fact baseline everything and start from the beginning. Or get an edelbrock carb. :D

I don't agree about the demon carbs. My experience with them has been very negative. Out of the box, everything was adjusted wrong. Way wrong, not a little. Not that I doubt the other poster's experience. Just giving my 2 cents.

Your engine doesn't seem to warrant a 4160 (troubles/tuning). I'd swap it for another carb.
kraventhearcher is offline   Reply With Quote
Old 04-27-2003, 11:14 AM   #5
L79vette
CF Senior Member
 
L79vette's Avatar
 
Member Since: Oct 2001
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

The other responders may be mixing up 4160 with 4150. 4150 is a double pumper, tough tuning and really a race part. 4160 is a vacuum secondary Holley, generally a very easy tune and a carb that came stock on my '67 and many other Chevys.

Sounds like your power valve is malfunctioning and dumping fuel at all times. Replace the power valve. If it is not a new carb, it probably wouldn't hurt to put a rebuild kit in it either just so you know everything else is good.
L79vette is offline   Reply With Quote
Old 04-27-2003, 01:19 PM   #6
TIMSPEED
CF Senior Member
 
TIMSPEED's Avatar
 
Member Since: Mar 2001
Location: Modesto CA
Send a message via AIM to TIMSPEED Send a message via Yahoo to TIMSPEED
Default Re: Holley 4160 Question: Stumble off Idle...? (L79vette)

It's a brand new Part #80460, now Holley says that they have a special thing to keep the Power Valve safe in the event of a backfire...and mine backfired through the carb as I was first starting up this new motor...so, should I put in a new power valve?? Or Power Valve Diaphragm?
TIMSPEED is offline   Reply With Quote
Old 04-27-2003, 03:13 PM   #7
Vetterodder
CF Senior Member
 
Vetterodder's Avatar
 
Member Since: Feb 1999
Location: Fountain Hills AZ
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

Make sure that you aren't uncovering too much of the transfer slots. Doing so causes the engine to idle on the main circuit instead of the idle circuit. The fact that the idle mixture screws don't have any affect suggests this possibility. Try turning the idle mixture screws out 1 1/2 turns on both sides and then turn down the idle speed screw. If the problem is exposed transfer slots that should fix it.
Vetterodder is offline   Reply With Quote
Old 04-28-2003, 03:33 AM   #8
TIMSPEED
CF Senior Member
 
TIMSPEED's Avatar
 
Member Since: Mar 2001
Location: Modesto CA
Send a message via AIM to TIMSPEED Send a message via Yahoo to TIMSPEED
Default Re: Holley 4160 Question: Stumble off Idle...? (Vetterodder)

Quote:
Make sure that you aren't uncovering too much of the transfer slots. Doing so causes the engine to idle on the main circuit instead of the idle circuit. The fact that the idle mixture screws don't have any affect suggests this possibility. Try turning the idle mixture screws out 1 1/2 turns on both sides and then turn down the idle speed screw. If the problem is exposed transfer slots that should fix it.
1 1/2 turns out from all the way LEAN?? How low should I turn my idle? 750rpm in drive "feels" smooth. Hopefully that trick'll work. I CAN'T believe this carb is needing a rebuild, it's seriously BRAND NEW (except for that backfire, but Holley says backfire's won't harm them)
TIMSPEED is offline   Reply With Quote
Old 04-28-2003, 10:39 AM   #9
Brettmc
CF Senior Member
 
Brettmc's Avatar
 
Member Since: Jul 2002
Location: St Louis MO
Send a message via AIM to Brettmc Send a message via Yahoo to Brettmc
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

Read Lars' Holley tuning paper. I put a brand-new-outta-the-box Holley 850 double-pumper on my 468 a coupla months back. It ran like crap. I emailed Lars, read his paper and followed his advice. Now that 850 runs perfectly. Shoot him an email, you'll be glad you did.

Brett
Brettmc is offline   Reply With Quote
Old 04-28-2003, 12:10 PM   #10
TIMSPEED
CF Senior Member
 
TIMSPEED's Avatar
 
Member Since: Mar 2001
Location: Modesto CA
Send a message via AIM to TIMSPEED Send a message via Yahoo to TIMSPEED
Default Re: Holley 4160 Question: Stumble off Idle...? (Brettmc)

ok, how do I get ahold of this Lars guy?
TIMSPEED is offline   Reply With Quote
Old 04-28-2003, 12:15 PM   #11
Brettmc
CF Senior Member
 
Brettmc's Avatar
 
Member Since: Jul 2002
Location: St Louis MO
Send a message via AIM to Brettmc Send a message via Yahoo to Brettmc
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

Quote:
ok, how do I get ahold of this Lars guy?
Email him at lars.grimsrud@lmco.com or send him an instant message or page him thru the C3 forum.

Here's a link to the Holley tuning paper:
http://corvetteforum.com/techtips/vi...=108&TopicID=3

Brett :thumbs:
Brettmc is offline   Reply With Quote
Old 04-28-2003, 12:54 PM   #12
TIMSPEED
CF Senior Member
 
TIMSPEED's Avatar
 
Member Since: Mar 2001
Location: Modesto CA
Send a message via AIM to TIMSPEED Send a message via Yahoo to TIMSPEED
Default Re: Holley 4160 Question: Stumble off Idle...? (Brettmc)

Thanks man! :cheers:
TIMSPEED is offline   Reply With Quote
Old 04-28-2003, 01:06 PM   #13
OBL1V1ON
CF Senior Member
 
OBL1V1ON's Avatar
 
Member Since: Nov 2002
Send a message via AIM to OBL1V1ON
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

You may have to adjust your floats. i had the same problem with a holly 650 dp and i found that my primary fuel bowl was getting a little too full, and when i would smash the gas a little too much gas would dribble into the intake along with the correct amount which made it pause a little then it would come out of it.

If its not your powervalve....Check you floats.
OBL1V1ON is offline   Reply With Quote
Old 04-28-2003, 07:28 PM   #14
kraventhearcher
Junior Member
 
kraventhearcher's Avatar
 
Member Since: Mar 2003
Location: Boone NC
Default Re: Holley 4160 Question: Stumble off Idle...? (L79vette)

Right, had my part numbers mixed up.
The lars paper is the way to go. Learning how to fix one thing is okay, but the key to keeping a holley happy is to Understand how the Entire carb works as a system for metering fuel.
Good Luck.
kraventhearcher is offline   Reply With Quote
Old 04-28-2003, 08:23 PM   #15
Vetterodder
CF Senior Member
 
Vetterodder's Avatar
 
Member Since: Feb 1999
Location: Fountain Hills AZ
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

Quote:
1 1/2 turns out from all the way LEAN?? How low should I turn my idle? 750rpm in drive "feels" smooth. Hopefully that trick'll work. I CAN'T believe this carb is needing a rebuild, it's seriously BRAND NEW (except for that backfire, but Holley says backfire's won't harm them)
Yes, from fully closed turn them counterclockwise. 1 1/2 turns is just a starting point and you may get a better vacuum reading with more or less. Try to keep the idle as low as you can and still be smooth in drive. Older Holley carbs (those produced more than about 10 years ago) could have their power valves damaged by backfires but that shouldn't be an issue with yours.
Vetterodder is offline   Reply With Quote
Old 04-29-2003, 12:46 PM   #16
TIMSPEED
CF Senior Member
 
TIMSPEED's Avatar
 
Member Since: Mar 2001
Location: Modesto CA
Send a message via AIM to TIMSPEED Send a message via Yahoo to TIMSPEED
Default Re: Holley 4160 Question: Stumble off Idle...? (Vetterodder)

Well gang, I think this video sums basically everything up
www.timspeed.com/TruckRun1.wmv
All I did was swap my primary jets from #62 (stock) to #64, as per Holley's instructions. But the funny thing is, I did that last night...then this morning when I started my truck, on the way to work, I had a TINY stumble...isn't that weird? I made NO changes to the carb in any way....hmmm...
TIMSPEED is offline   Reply With Quote
Old 04-29-2003, 02:28 PM   #17
Brettmc
CF Senior Member
 
Brettmc's Avatar
 
Member Since: Jul 2002
Location: St Louis MO
Send a message via AIM to Brettmc Send a message via Yahoo to Brettmc
Default Re: Holley 4160 Question: Stumble off Idle...? (TIMSPEED)

Small changes can yield large effects in carbs. Glad it's runnin better!

Brett :thumbs:
Brettmc is offline   Reply With Quote
Old 04-29-2003, 02:28 PM
 
Go Back   Corvette Forum > C3 Corvettes, 1968 - 1982 > C3 Tech/Performance
Reload this Page Holley 4160 Question: Stumble off Idle...?
 
 
 
Reply

Tags
4160, 80460, accelerator, carb, drive, fix, hesitation, holley, idl, idle, low, pump, rebuilt, stumble, 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
TriPower Engine idle issue zuendler C3 Tech/Performance 13 06-08-2014 03:44 PM
how hot and vacuum advance? big69 C3 Tech/Performance 2 07-14-2005 02:01 PM
Vacuum advance - Carb question Help viperjesse C3 Tech/Performance 12 11-13-2004 10:11 PM
Vacuum Explained: Manifold, Venturi & Ported - New Article by Lars lars C1 & C2 Corvettes 21 09-14-2003 10:39 PM
Vacuum Explained: Manifold, Venturi & Ported - New Article by Lars lars C3 Tech/Performance 20 09-13-2003 09:25 AM


All times are GMT -4. The time now is 05:50 AM.


Emails & Password Backup