Holley 250 blower too lean on cylinders 1 and 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
  #1 (permalink)  
Old 09-06-2008, 03:40 PM
471A
 
Last photo:
Join Date: Jun 2008
Location: Oregon
Posts: 148
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Holley 250 blower too lean on cylinders 1 and 2

Multiple engine dyno runs on my SBC 355 with a Holley 250 blower and Edelbrock AVS 800 yielded exhaust temperatures close to 1500 degrees on cylinders 1 and 2 while none of the other cylinders exceeded 1350. This remained true regardless of jetting changes, ranging from .103 to .110 secondary and .113-.116 primary. We also ran the springs and rods which Edelbrock prescribes when the 800 is used with a blower. We suspect that insufficient fuel is reaching cylinders 1 and 2 for two reasons. First, the Holley 250 uses an elongated design. This may be pushing the fuel flow towards the rear cylinders and away from the front. Second, the single carb mounting flange places that carb over the center of the blower. My question is this: Has any among you ran a single carb on a Holley or Weiand 250, but used the dual carb mounting flange, with the rear flange sealed off and the single carb mounted forward ? This would move the carb and its fuel flow forward several inches, perhaps better feeding cylinders 1 and 2. (No, I don't want to run dual carbs.)

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 09-08-2008, 02:21 PM
Registered User
 
Join Date: May 2006
Location: San Diego, CA
Posts: 26
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
You might want to try carb adapter plate Weiand 93153 - it's exactly what you're looking for.

Good luck,
Ran
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-09-2008, 09:34 AM
471A
 
Last photo:
Join Date: Jun 2008
Location: Oregon
Posts: 148
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
250 blower too lean

Ran, Wow ! That offset single carb adapter is exactly what is needed. Thank you very much for your expertise and taking the time to respond.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 09-10-2008, 12:19 PM
Registered User
 
Join Date: May 2006
Location: San Diego, CA
Posts: 26
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Glad to be of help. Now I need to check if the 250 I have in a box in the garage has the centered adapter or the offset one. It's not going to go on a Chevy (on a small block Mopar instead), but I have a feeling that I might experience the same problem.
Thanks for bringing this up.
Ran
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 09-10-2008, 12:34 PM
471A
 
Last photo:
Join Date: Jun 2008
Location: Oregon
Posts: 148
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Holley-Weiand tech

After your suggestion, I called Holley-Weiand tech and spoke with a supercharger specialist named "Tom". He said that Holley encourages running the 250 with two small 4 barrels but acknowledged that the 250 can be run on a larger, single 4 barrel. He added that the offset adapter was developed precisely because with a "centered" 4 barrel, the front two cylinders often run lean. Good luck with the Mopar !
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 09-11-2008, 12:16 PM
Registered User
 
Join Date: May 2006
Location: San Diego, CA
Posts: 26
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks!
Ran
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



All times are GMT -6. The time now is 12:24 PM.


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.