holley 4777-7 issues - 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
lost password?   |   register now

LinkBack Thread Tools
  #1 (permalink)  
Old 08-12-2010, 11:43 AM
Registered User
Join Date: Jul 2010
Location: midwest
Posts: 10
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
holley 4777-7 issues

I have tried a used-new to me 4777-7 650 on my 355 sbc. I also have swapped over to a 850dp w/ 750 base from another of my cars & it runs as it should. I have new MSD dist.,coil,plug wires & 6AL box.

I taken the 650 apart & blown things out & all checks out ok.
It runs, but doesn't idle very well & has a lag @ the hit of the throttle, even @ a slow rate. It sometimes pops . I have replaced the pv w/ another 6.5.
It did have a electric choke & I replaced it w/ a manual & did cover the vacuum source that the electric used.
It seems to have a vacuum leak & I have used carb. cleaner around the base & at the sides of the carb. w/ no change in idle speed. I have all the vacuum ports plugged on the carb.

Thanks for any ideas!!

Reply With Quote Quick reply to this message
Sponsored Links
  #2 (permalink)  
Old 08-12-2010, 02:26 PM
cobalt327's Avatar
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Posts: 5,031
Wiki Edits: 1616

Thanks: 128
Thanked 616 Times in 565 Posts
I would start by using a straight edge to check both metering blocks for warpage, as well as the main body.

Many times, a used carb will have been "modified" by some ham-fisted PO, who did more harm than good. So, what I will always suggest, is baseline it back to stock, and work forward from there.

Jets, Primary- 67
Jets, Secondary-73

Power valve- 65

Primary accelerator pump shooter- 0.028"
Secondary accelerator pump shooter- 0.028"

Accelerator pump cam- white (IIRC)

There are subtle differences in the base gaskets, be sure the one you're using is correct.

Be sure you're using the correct power valve gasket (shouldn't have any "fingers" to locate the valve- just a simple ring shaped gasket), and that it's not too thin, allowing the PV to seat before it is sealed fully.

The off idle stumble could be related to the accelerator pump adjustment. Be sure the throttle linkage moves the pump arm the instant that it moves, and that there's fuel discharged from the nozzles, also instantly. There should be at least 0.015" clearance between the arm and linkage at WOT. If there isn't the pump diaphragm can be damaged.

There are two check valves for the accelerator pump one under the nozzles (will be a long needle)- and one under the diaphragm (will be a red rubber "umbrella"). They all must be there, and sealing, or the fuel will leak back into the bowl and this causes a lag in the fuel delivery through the nozzles.

Good luck and ask if there's anything else that you think of.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 08-13-2010, 04:27 PM
Registered User
Join Date: Jul 2010
Location: midwest
Posts: 10
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I pulled it back off to go over it .
I changed meter block gaskets, inlet needle & seats.
I checked the base for straightness & where the metering block sit on the carb., also the base plate.
I reset secondary's to set the transfer slots. I check vacuum @ the large port of the carb.. It measured 8. I had a 6.5 pv in the front & changed over to a 3.5. It had 28 squirters, now has 31's in it. Still has 67 jets in front & 73 in the rear.
It does run better than it had, but still sounds like it's missing down low. Seems to run better when it's up in the rpm range, but still not crisp.

Pulled off & swapped back the other carb & it's running as it should
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply

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:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


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
question about my camaro and holley carb Joe85z28 Engine 8 07-28-2010 11:07 AM
Quick fuel HR 650 or Holley 4777? Onsjos Engine 8 07-19-2010 03:53 AM
Holley fuel pump, return line or not to return line??? JD's camaro Engine 1 07-16-2010 05:17 PM
should i use a holley blue top or a manual fuel pump? 406 ss monte Engine 18 12-10-2007 07:39 PM
edelbrock vs. holley carb Super Chevy Engine 43 01-21-2006 09:55 PM

All times are GMT -6. The time now is 10:21 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.