Results 1 to 9 of 9

Thread: Civvy dist centrifical advance curve

  1. #1
    Join Date
    Feb 2009
    Location
    Northern California
    Posts
    467

    Default Civvy dist centrifical advance curve

    Any ideas what the proper advance curve is? I've been having problems lately with backfiring and dieseling, so bought a timing light (mine back home doesn't do me much good here!), and checked the timing, thinking it might have drifted since last time I set it. It tested perfect 5 degrees at 650rpm, but for the heck of it, played with my idle speed knob...

    450rpm: 0 BTDC
    650rpm: 5 BTDC
    800rpm: 10 BTDC
    1000rpm: 15 BTDC
    1200rpm: 20 BTDC
    1500rpm: 25ish BTDC (off the end of the scale)
    Anything higher: 27ish BTDC

    That's a pretty steep advance curve... Is that normal for these, or are my springs bad? It's a civvy dist, with the vacuum advance disconnected and capped. I'd normally expect to hit 25 degrees around 3K-4K...

    --Randy

  2. #2
    Join Date
    Feb 2009
    Location
    Northern California
    Posts
    467

    Default

    Actually, 450rpm is around -5 BTDC, rather retarded...

    --Randy

  3. #3
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
    Posts
    11,520

    Default

    Does that mean 5 ATDC then at 450 RPM?

    I have to look but I think i saw the curve in one of my civvy books some time back...
    Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

    Pro-choice, that's a LIE, babies don't choose to die!!

  4. #4
    Join Date
    Feb 2009
    Location
    Northern California
    Posts
    467

    Default

    yes, 5 ATDC. I figured it made it clearer to use a negative than switch terms.

    If the curve is right, it's the fastest advance curve I've ever seen - If it's not, I'm thinking I might need to pull it apart and make sure I don't have a broken spring. Or ignore it, as it runs pretty well.

    The backfire and dieseling are getting annoying, though... when I stop, it will diesel for about ten seconds, and stopping the dieseling by letting off the clutch creates a rather impressive (and damaging to the exhaust system, from the number of new holes it's developed) backfire. Idle is set down at 450-500rpm, so that shouldn't be causing it...

    --Randy

  5. #5
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
    Posts
    11,520

    Default

    I usually stand on the gas pedal if the motor runs on...not let the clutch out...

    Ill let you know if I can find it...
    Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

    Pro-choice, that's a LIE, babies don't choose to die!!

  6. #6
    Join Date
    Jul 2007
    Location
    Rhoadesville, Virginia (five miles from no place)
    Posts
    5,125

    Default

    If there is a fair amount of carbon buildup on the tops of the pistons, it can cause the dieseling too. Acts like a glow plug once its good and hot.
    "Free advice is worth what you pay for it."™

  7. #7
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
    Posts
    11,520

    Default

    I have no data for you...checked the source book that i thought I had seen it in and nada...sorry.
    Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

    Pro-choice, that's a LIE, babies don't choose to die!!

  8. #8
    Join Date
    Feb 2009
    Location
    Northern California
    Posts
    467

    Default

    Thanks for checking!

    --Randy

  9. #9
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
    Posts
    11,520

    Default

    Wish you were thanking me for a result...
    Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

    Pro-choice, that's a LIE, babies don't choose to die!!

Similar Threads

  1. Vacuum Advance
    By rpgdeity in forum Modified Tech
    Replies: 7
    Last Post: February 27th, 2011, 06:23 PM
  2. Civy dist.
    By johnny rezny in forum Open Discussion
    Replies: 3
    Last Post: April 3rd, 2009, 07:31 PM
  3. Civy dist cap?
    By johnny rezny in forum Open Discussion
    Replies: 4
    Last Post: February 15th, 2009, 03:31 PM
  4. Can I go 12v and still keep 24v Dist.
    By ASHWOOD in forum Modified Tech
    Replies: 3
    Last Post: August 26th, 2008, 09:53 AM
  5. Mil. Dist. Cap
    By adk4x4 in forum Open Discussion
    Replies: 4
    Last Post: May 4th, 2007, 09:56 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Site Upgrade, Design Modifications & Administrative Support by:
Palm River Enterprises LLC, IT Solutions
President: Tom King, User ID=teking
This site is owned and operated by:
M715 Zone, LLC
President: Jon Schmidt, User ID=brute4c


If you have any suggestions, comments, problems or questions, contact:  brute4c@m715zone.com
Use of this site means you understand and agree to our TERMS OF USE

Copyright Notice:
This web site is subject to the protection of the copyright laws of the United States and other countries. Except for Personal Use Only, you may not modify, copy, distribute, transmit, display, perform, reproduce, publish, license, create derivative works from, transfer, or sell any information obtained from any part of the M715 Zone website without the prior written permission of M715 Zone, LLC. Written permission can only be obtained by contacting brute4c@m715zone.com

Copyright 1998-2024