Holley 600 - set idle speed using secondary blade - Ford Muscle Forums : Ford Muscle Cars Tech Forum
 2Likes
Reply
LinkBack Thread Tools
post #1 of 20 (permalink) Unread 09-06-2019, 02:15 PM Thread Starter
Registered User
 
Join Date: May 2018
Posts: 158
Holley 600 - set idle speed using secondary blade

I was browsing the net and found this you tube video.

https://youtu.be/oBOrWUPhYto

It gives instructions on how to tune the idle speed by opening the secondary blade so the primary transition
slot remains at the recommended square configuration.

Has anyone tried this? Were your results positive or negative? Any other commentary is appreciated.

I might give this a try. On my engine, I need to have the transition slot open between 1/8 - 3/16 of an inch
and the idle air screws turned in to 1/2 + 1/16 turn in order to get an A/F ratio in the range of 13.9 - 14.2.

To me, this isn't how the carb was designed to be set up.

Thanks
65merccyclone is offline  
Sponsored Links
Advertisement
 
post #2 of 20 (permalink) Unread 09-06-2019, 04:17 PM
Registered User
 
Join Date: Jun 2018
Posts: 400
Re: Holley 600 - set idle speed using secondary blade

i don't know how to search the forum for it, but the subject has been covered a bunch
extech is offline  
post #3 of 20 (permalink) Unread 09-07-2019, 11:08 AM
Subscriber
 
Join Date: May 2010
Posts: 484
Re: Holley 600 - set idle speed using secondary blade

Quote:
Originally Posted by 65merccyclone View Post
On my engine, I need to have the transition slot open between 1/8 - 3/16 of an inch
and the idle air screws turned in to 1/2 + 1/16 turn in order to get an A/F ratio in the range of 13.9 - 14.2.

To me, this isn't how the carb was designed to be set up.

transition slot opened to 3/16" = more air than normal
idle screws turned in to 1/2 turn = less fuel than normal

so it seems like your idle circuit is super-rich, for some reason.
is this a new carb, or has it been around the block a few times? the standard 600 doesn't have idle adjustments on the secondary, so i'm not sure what would cause the idle circuit to be pouring so much fuel.
cuthrell is offline  
 
post #4 of 20 (permalink) Unread 09-07-2019, 01:03 PM
Registered User
 
Join Date: Jun 2018
Posts: 400
Re: Holley 600 - set idle speed using secondary blade

because the tranfer slots are uncovered. the idle mix screws dont affect it
extech is offline  
post #5 of 20 (permalink) Unread 09-07-2019, 01:28 PM
Subscriber
 
Join Date: May 2010
Posts: 484
Re: Holley 600 - set idle speed using secondary blade

Quote:
Originally Posted by extech View Post
because the tranfer slots are uncovered. the idle mix screws dont affect it
i think i'm following what you're saying-
since the transfer slots are completely uncovered, he's pulling fuel through the main circuit, instead of just the idle circuit?
cuthrell is offline  
post #6 of 20 (permalink) Unread 09-07-2019, 05:55 PM
Registered User
 
Join Date: Jun 2018
Posts: 400
Re: Holley 600 - set idle speed using secondary blade

no, its
through the idle restrictor, but idle is usually reduced by the mix screws. the mix reduction at the screw is bypassed
extech is offline  
post #7 of 20 (permalink) Unread 09-08-2019, 09:56 AM Thread Starter
Registered User
 
Join Date: May 2018
Posts: 158
Re: Holley 600 - set idle speed using secondary blade

Quote:
Originally Posted by cuthrell View Post
transition slot opened to 3/16" = more air than normal
idle screws turned in to 1/2 turn = less fuel than normal

so it seems like your idle circuit is super-rich, for some reason.
is this a new carb, or has it been around the block a few times? the standard 600 doesn't have idle adjustments on the secondary, so i'm not sure what would cause the idle circuit to be pouring so much fuel.
In order to get the car to idle at the recommended 850 rpm, I need to open the curb idle screw to where the transition slot is open too much. I should have made an exact measurement but it was open way too much. To combat this, I have to close the idle screws too tight.

It is a new carb. The float levels have been checked. The fuel pump is a manual and has the correct pressure so I don't think fuel is overflowing into the engine.

What I want to do is get more air into the engine at idle so the transition slot can be set correctly, which will allow the idle screws to be set correctly.

I thought about putting holes in the primary blades too. I'm not sure what size to start with. The problem with this solution is there isn't a means of reversing the change. Thanks
65merccyclone is offline  
post #8 of 20 (permalink) Unread 09-08-2019, 09:59 AM Thread Starter
Registered User
 
Join Date: May 2018
Posts: 158
Re: Holley 600 - set idle speed using secondary blade

Quote:
Originally Posted by extech View Post
i don't know how to search the forum for it, but the subject has been covered a bunch

I found a few threads that mentioned it can be done but none give any specifics on what someone did, like how many turns of the screw or how far they opened the gap from stock. I'll do some more searching to see what I come up with. thanks
65merccyclone is offline  
post #9 of 20 (permalink) Unread 09-08-2019, 11:10 AM
Subscriber
 
Join Date: Jan 2004
Location: Omaha, NE
Posts: 3,784
Re: Holley 600 - set idle speed using secondary blade

It's the way it should be done, it allows you to stay in the idle circuit, otherwise depending how deep you are, you could either have drippy transition slots, or even drippy boosters too.

70 Sportsroof, 427 FE/489 cid, TKO-600, 31 spline 4.10, A/C. modified Mass-flo EFI/reprogrammed A9L/CnC ported Victor.
My427stang is offline  
post #10 of 20 (permalink) Unread 09-09-2019, 04:41 AM
Subscriber
 
Join Date: May 2010
Posts: 484
Re: Holley 600 - set idle speed using secondary blade

Quote:
Originally Posted by My427stang View Post
, you could either have drippy transition slots, or even drippy boosters too.
this is what i'm thinking too.
can you look down the carb with the engine running? use a big handheld mirror if necessary.
cuthrell is offline  
post #11 of 20 (permalink) Unread 09-09-2019, 08:15 AM
Registered User
 
Join Date: Jun 2018
Posts: 400
Re: Holley 600 - set idle speed using secondary blade

just put "secondary throttle" in the search forum place. tons of info
extech is offline  
post #12 of 20 (permalink) Unread 09-09-2019, 02:39 PM
Subscriber
 
Join Date: May 2010
Posts: 484
Re: Holley 600 - set idle speed using secondary blade

what engine is this carb on?
what happens when its set to stock?


found this on another forum:
really the only reason to adjust the blade positon is to correct the throttle blade/transfer slot relationship. since the transfer slots are not metered by the idle mixture screws, if there is too much of the transfer slot exposed the engine will run rich at idle.

if your idle mixture screws have little to no effect then likely too much of the transfer slot is exposed.

my holley rebuild manual states that .040 - .065 of the transfer slots should be exposed. but in my experience ive had to close them down to .020 - .025 to get the idle cleaned up.
cuthrell is offline  
post #13 of 20 (permalink) Unread 09-09-2019, 03:21 PM Thread Starter
Registered User
 
Join Date: May 2018
Posts: 158
Re: Holley 600 - set idle speed using secondary blade

Quote:
Originally Posted by cuthrell View Post
this is what i'm thinking too.
can you look down the carb with the engine running? use a big handheld mirror if necessary.

I looked at the carb at idle and didn't see any drips coming from the shooters.



The carb has these components in it



66 mains, 33 shooters, dark blue pump cam (2nd position) and, silver (i think) secondary spring)
65merccyclone is offline  
post #14 of 20 (permalink) Unread 09-09-2019, 03:24 PM Thread Starter
Registered User
 
Join Date: May 2018
Posts: 158
Re: Holley 600 - set idle speed using secondary blade

Quote:
Originally Posted by cuthrell View Post
what engine is this carb on?
what happens when its set to stock?


found this on another forum:
really the only reason to adjust the blade positon is to correct the throttle blade/transfer slot relationship. since the transfer slots are not metered by the idle mixture screws, if there is too much of the transfer slot exposed the engine will run rich at idle.

if your idle mixture screws have little to no effect then likely too much of the transfer slot is exposed.

my holley rebuild manual states that .040 - .065 of the transfer slots should be exposed. but in my experience ive had to close them down to .020 - .025 to get the idle cleaned up.

It is a 4160- 600, 80457-13. It's my goal to get the transfer slot set close to the factory recommendation. I don't have a feeler gauge that will allow me to make an accurate measurement. Going by eyeball.
65merccyclone is offline  
post #15 of 20 (permalink) Unread 09-09-2019, 08:30 PM
Registered User
 
Join Date: Jun 2018
Posts: 400
Re: Holley 600 - set idle speed using secondary blade

so for your application, factory specs dont work as they are for an engine that makes plenty of vacuum.. you do need to open the secondary plates some to allow enough air in with the idle mix without exposing the transfer ports. or... modify the primary and or secondary plates with holes
extech is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Muscle Forums : Ford Muscle Cars Tech Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
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:
OR

Log-in











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



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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome