Holley Hesitation - Page 2 - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #16 (permalink)  
Old 02-25-2011, 05:35 PM
Registered User
 
Last photo:
Join Date: May 2008
Location: ohio
Posts: 1,309
Wiki Edits: 0

Thanks: 6
Thanked 33 Times in 31 Posts
I have a holley 1850 600 carburetor like you have and the 570 street avenger won't be even close to that carb for the fuel curve. I have a holley 670 street avenger sitting on the side at the moment and it is in all purposes the same identical carb to the holley 600. The only difference is it has a secondary metering block with jets and a quick change vacuum secondary and center hung fuel bowls.

I have taken both carbs apart and they have the same exact part numbers on the primary metering blocks, towers, and same base plate and boosters. I also got the secondary metering block kit for my 1850 carb and its the same rear metering block that the 670 comes with.

Anyways you won't get the same response from the 570 as you would a 600/670 holley. The 570 has smaller bores then the 600 andI doubt that the 670 or the other street avengers really flow that much as the knock off brands flow 580/680/780 so called to speak with out really having them checked.

Anyways I have had the same issue as you have had and the only way that 570 carb will ever work as suggested above is you will need a richer idle mixture circuit.

I have been fine tweeking mine for the last year now and had it pretty good until I had my engine redone and put in a very slightly different cam and now it appears its ugly head here and there.

Mine does fine if I am at a dead stop and smash it or while cruising and smash it and its fine but if I just ever so slightly open the throttle and ease into it it will stumble till I get my rpms up to 1600 or more. I have read countless posts about the avenger carbs being very lean out of the box.

Try jetting up a few sizes and and check your pump cam and squirter size's like you have along with making sure your transfer slot is not exposed too much at idle. I have learned if its showing too much that can cause that to. Post back and let us know what you find out after some changes.

I rejeted mine up two sizes from stock and it does make a big difference. some might agree with me but there are always differences which is nice it always gives good ideas on things to check. I like the guys who are helpfull on here.
Take care
Eric
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #17 (permalink)  
Old 02-25-2011, 06:01 PM
Registered User
 
Join Date: Feb 2011
Location: Western Australia
Posts: 3
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 57halfton
I put a Holley 570 cfm Street Avenger on the 350 in my pickup today and everything seems to work fine except I get a slight hesitation or bog if i'm driving around town and touch the throttle to speed up in normal driving. I took off a 1850 Holley 600 cfm and it didn't bog or hesitate like the Street Avenger does. My old truck is a driver and dose'nt see any WOT , i'm just concerned with drive ability. Is this an accelerator pump problem maybe ????
Holley carbs are relatively easy to set up. firstly check your float levels, this can be done by removing the brass plugs in the side of the float bowl, adjust the height of your float until fuel comes up or down to the level of the brass plug hole.
Next i like to adjust my mixture, to do this the little screws in the side of the metering block can be adjusted to get the best idle, I like to adjust my idle a little high and then adjust the metering screws out until i get the correct idle speed, I also like to have these screws almost all the way out, this will liven up your throttle responce and remove the flat spot.
Reply With Quote Quick reply to this message
  #18 (permalink)  
Old 02-26-2011, 08:47 AM
Registered User
 
Last photo:
Join Date: May 2006
Location: Napa , Ca.
Posts: 292
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
What are the transfer slots or transition slots ????
Gene
Reply With Quote Quick reply to this message
  #19 (permalink)  
Old 02-26-2011, 10:19 AM
Registered User
 
Last photo:
Join Date: Oct 2007
Location: Portland,Or
Posts: 820
Wiki Edits: 0

Thanks: 0
Thanked 40 Times in 34 Posts
They are some holes, or slotted passages that are just above the throttle plate when the throttle is completely closed, but are below the throttle plate after it is opened a little bit.

They help the carburetor transition from running on the idle circuit only to having the fuel be metered by the main jets, and the venturi of the carburetor when the throttle plate is opened a fair amount.

If your throttle plate is opened too far, when the engine idling, the transition slots become the idle circuit, and then they do not function to get the engine off idle.
Reply With Quote Quick reply to this message
  #20 (permalink)  
Old 02-26-2011, 10:56 AM
Registered User
 
Last photo:
Join Date: May 2010
Location: Des Moines,Iowa
Posts: 101
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Check out www.holley.com and look for news and media....Once your in there click on Holley TV-There are several videos on tuning the carb including the transition slot, power valve, etc.....Im going to do a few adjustments today and see if I can correct the hesitation im getting.




Quote:
Originally Posted by 57halfton
I put a Holley 570 cfm Street Avenger on the 350 in my pickup today and everything seems to work fine except I get a slight hesitation or bog if i'm driving around town and touch the throttle to speed up in normal driving. I took off a 1850 Holley 600 cfm and it didn't bog or hesitate like the Street Avenger does. My old truck is a driver and dose'nt see any WOT , i'm just concerned with drive ability. Is this an accelerator pump problem maybe ????
Reply With Quote Quick reply to this message
  #21 (permalink)  
Old 02-26-2011, 11:27 AM
66GMC's Avatar
Get in, sit down, hang on
 

Last journal entry: Cab Removal
Last photo:
Join Date: May 2005
Location: Olds, Alberta Canada
Age: 56
Posts: 2,761
Wiki Edits: 0

Thanks: 32
Thanked 89 Times in 84 Posts
Yep, you're getting some good advice here, IMO.
Many of us are guilty of pointing fingers at the carb.

Start by ensuring the basics are set up right ... fuel delivery, float level, idle mixture, curb idle, engine timing, ignition system, plugs, etc.

It's also common for many of us to think that changing main jets will solve a stumble problem. IMO, the stumble is caused by a TRANSITION problem ... either on the primary or secondary side. It's *critical* to have that transfer slot covered by the primary throttle plates. Without that, adjusting the mixture screws won't have any effect.

Also ... If you have those secondaries crashing in too soon ... you'll get the "Mooooooo" sound until the air velocity is sufficent to draw fuel.
I can't tell you how many vacuum secondary carbs I have seen with a sheet-metal screw jammed into the secondary throttle lever ... effectively FORCING the carb to have nechanical secondaries.

In summary...
Accelerator pump and power valve are your "transition" components. Once everything else is adjusted properly, this is where to focus your "tuning" attempts.
Reply With Quote Quick reply to this message
  #22 (permalink)  
Old 02-26-2011, 12:58 PM
Registered User
 
Last photo:
Join Date: May 2006
Location: Napa , Ca.
Posts: 292
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Well i'm sure this is going to get some interesting feedback. I went out this morning and was tinkering with my carb , I took off the float bowl and metering block from the avenger carb and looked at it the jets were #54 and the power valve looked like a 58 with a C then I compared that with the metering block from the 600 it had #64 jets and a power valve with a 65 on it and the metering blocks look the same so I put the 600 metering block on the avenger carb and took it for a ride around the block a few times and everything seems to work perfectly, no more bog. I know going from 54 jets to 64 sounds like a lot so i'm going to drive it around some more and then take a look at the spark plugs again, they are a light tan color after going around the block a couple of times. I'll check them later, might be a little fat.
I'll keep you guys posted, thanks for your help.
Gene
Reply With Quote Quick reply to this message
  #23 (permalink)  
Old 02-26-2011, 01:12 PM
Registered User
 
Last photo:
Join Date: May 2010
Location: Des Moines,Iowa
Posts: 101
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
For comparison, the jets in my 670 are 65 front/68 rear with a 6.5 PV. Hoping it works out for ya-keep us posted.


Quote:
Originally Posted by 57halfton
Well i'm sure this is going to get some interesting feedback. I went out this morning and was tinkering with my carb , I took off the float bowl and metering block from the avenger carb and looked at it the jets were #54 and the power valve looked like a 58 with a C then I compared that with the metering block from the 600 it had #64 jets and a power valve with a 65 on it and the metering blocks look the same so I put the 600 metering block on the avenger carb and took it for a ride around the block a few times and everything seems to work perfectly, no more bog. I know going from 54 jets to 64 sounds like a lot so i'm going to drive it around some more and then take a look at the spark plugs again, they are a light tan color after going around the block a couple of times. I'll check them later, might be a little fat.
I'll keep you guys posted, thanks for your help.
Gene
Reply With Quote Quick reply to this message
  #24 (permalink)  
Old 02-26-2011, 03:33 PM
lg1969's Avatar
Google "Tunnel Ram 406"
 
Last photo:
Join Date: Oct 2007
Location: Bohemia, L.I.N.Y.
Age: 64
Posts: 1,047
Wiki Edits: 0

Thanks: 1
Thanked 21 Times in 18 Posts
Gene, Looks like the trick works. Good to know.
Reply With Quote Quick reply to this message
  #25 (permalink)  
Old 02-26-2011, 04:27 PM
ericnova72's Avatar
More for Less Racer
 
Join Date: Jan 2007
Location: S.W. Lower Michigan
Age: 47
Posts: 7,662
Wiki Edits: 0

Thanks: 10
Thanked 148 Times in 136 Posts
Quote:
Originally Posted by 57halfton
Well i'm sure this is going to get some interesting feedback. I went out this morning and was tinkering with my carb , I took off the float bowl and metering block from the avenger carb and looked at it the jets were #54 and the power valve looked like a 58 with a C then I compared that with the metering block from the 600 it had #64 jets and a power valve with a 65 on it and the metering blocks look the same so I put the 600 metering block on the avenger carb and took it for a ride around the block a few times and everything seems to work perfectly, no more bog. I know going from 54 jets to 64 sounds like a lot so i'm going to drive it around some more and then take a look at the spark plugs again, they are a light tan color after going around the block a couple of times. I'll check them later, might be a little fat.
I'll keep you guys posted, thanks for your help.
Gene
There is very likely more to this than just jet sizing, that you aren't seeing. There are two other fuel metering restrictions that are in play here - the power valve channel restrictions(PVCR), and the idle fuel feed restrictons.(IFR).

The PVCR are sized to compliment the main jet sizing to give correct WOT power fuel mixtures, and are located just below the threads in the power valve bore, you have to remove the valve to see them. These could be a different size than the ones in the 570 Avenger, along with the fact the power valve may have a different vacuum level opening rating(the "58" and "C" are not the rating).

The IFR's are located on the back side of the metering block, behind and slighly above were the main jets are on the opposite side, and at the bottom of the long slot areas of the metering block, they're a small brass restriction drilled anywhere from .025-.045". These may also be bigger(likely) in the 600 block than they are in the 570 block. These restrictions feed the idle emulsion(air/fuel) well and on to the idle mixture needles, and feed the transition slots.

Just some info to help anyone who may be looking at this thread, now and in the future.

The 64 jet you have now wil likely be too rich, I'd expect about 60 to be correct.

Glad to see it made a big improvement, now you just need to fine tune main jetting.
Reply With Quote Quick reply to this message
  #26 (permalink)  
Old 02-26-2011, 04:32 PM
ericnova72's Avatar
More for Less Racer
 
Join Date: Jan 2007
Location: S.W. Lower Michigan
Age: 47
Posts: 7,662
Wiki Edits: 0

Thanks: 10
Thanked 148 Times in 136 Posts
Quote:
Originally Posted by Blownchevelle68
For comparison, the jets in my 670 are 65 front/68 rear with a 6.5 PV. Hoping it works out for ya-keep us posted.
Just for your info, those jet sizes are typically what are found in the List 1850 600 cfm Vacuum secondary, so it is easy to see how they would be lean on a 670 cfm carb. I'd go to 70 front/74 rear as a place to start.

You'll likely still need to increase the idle feed restrictors unless you change metering blocks.
Reply With Quote Quick reply to this message
  #27 (permalink)  
Old 02-26-2011, 05:05 PM
Registered User
 
Last photo:
Join Date: May 2010
Location: Des Moines,Iowa
Posts: 101
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Sounds good I will give those jets a try!! Thanks !!


Quote:
Originally Posted by ericnova72
Just for your info, those jet sizes are typically what are found in the List 1850 600 cfm Vacuum secondary, so it is easy to see how they would be lean on a 670 cfm carb. I'd go to 70 front/74 rear as a place to start.

You'll likely still need to increase the idle feed restrictors unless you change metering blocks.
Reply With Quote Quick reply to this message
  #28 (permalink)  
Old 06-21-2012, 10:34 AM
Registered User
 
Join Date: Jun 2012
Posts: 1
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Runs like a champ now

In February, I purchased a 64 El Camino with a completely rebuilt 327 with a new 570 Holley Street Avenger. I had problems with it stumbling when I punched the gas. At times I would also experience it coughing and/or stumbling when I shifted to a higher gear. My mechanic checked the timing, spark plugs, ignition and found all okay. He ended up replacing the 65 power valve with a new 65 power valve and placed a larger gas jet on the squirter. Unfortunately there was no improvement.

I did a google on the problem and found this thread, printed it out, and gave to my mechanic to read. I took the car in again. My mechanic said, "Wow this thread makes sense - emission carburetor, metering box, transition problem". He replaced my metering block with a Holley 600 metering block with #61 gas jets which he had on hand, and replaced the larger gas jet in the squirter with the original #31 gas jet. I took it out for a test run and I could not believe the difference! All problems GONE! Runs like a champ now.

So to all of you I say THANK YOU!
Reply With Quote Quick reply to this message
  #29 (permalink)  
Old 06-21-2012, 12:24 PM
1BAD80's Avatar
The Smell of Nitro in the morn
 
Last wiki edit: How to adjust valves Last photo:
Join Date: Jun 2001
Location: Mich
Posts: 2,423
Wiki Edits: 2

Thanks: 0
Thanked 2 Times in 2 Posts
A bog is to big of a shot & a backfire is to lean not enough of a shot.
The cam determines the amount and how long of a shot it get's.
This has been gone thru many times, try doing a Search this Site.

There is plenty of info in the Knowledge Base on this site http://www.hotrodders.com/kb/carburetor-articles
Which will help you tune your carb in perfectly.

You must have .015 play in the arm at full open or you can tear the rubber diaphragm and then be SOL
__________________
Luv the smell of NITRO in the morning.
Reply With Quote Quick reply to this message
  #30 (permalink)  
Old 06-21-2012, 04:30 PM
lg1969's Avatar
Google "Tunnel Ram 406"
 
Last photo:
Join Date: Oct 2007
Location: Bohemia, L.I.N.Y.
Age: 64
Posts: 1,047
Wiki Edits: 0

Thanks: 1
Thanked 21 Times in 18 Posts
Heyman, Looks like it works changing the metering block. Like I mention before, Change the jets or power valve or changing pump cam will not cure the problem. IT's just a band aid.
When you are dealing with emissions carburetor the idle circuit is so leaned out to the point of bogging off the line. When using a performance cam the manifold vacuum will be low, and the idle circuit will not respond. Emission type Carburetor need high manifold vacuum like a cam very high 112* or higher overlap time. In another words a small cam.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Holley 4150 bog/hesitation Please HELP!! vortec86z29 Engine 32 05-24-2010 11:08 PM
Would this Holley problem cause hesitation? Argess Engine 2 09-09-2009 01:38 PM
Hesitation! frankenvette Engine 17 05-18-2006 04:55 PM
Holley hesitation harrassment Neal Green Engine 12 11-25-2004 11:36 PM
Holley - hesitation off idle snod83 Engine 1 06-14-2004 03:48 PM


All times are GMT -6. The time now is 06:35 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.