Results 1 to 13 of 13

Thread: 253 backfiring.

  1. #1
    casual poster
    Join Date
    Jan 2017
    Location
    Melbourne
    Posts
    59

    Default 253 backfiring.

    Gents,
    I started my HZ 253 today after it had been sitting for around 12 months, initially it started and run ok, then after it idled for maybe a minute it started missing / popping, running on 7 and would backfire at any revs above idle....The motor is stock apart from a Holden large cap electronic distributor.

    Any help much appreciated!
    Last edited by Oz_ek; 28-05-2021 at 09:20 PM.

  2. #2
    casual poster marras's Avatar
    Join Date
    Sep 2009
    Location
    perth
    Posts
    62

    Default

    Bad fuel and fouled the plugs maybe.

  3. #3
    casual poster
    Join Date
    Jan 2017
    Location
    Melbourne
    Posts
    59

    Default

    Quote Originally Posted by marras View Post
    Bad fuel and fouled the plugs maybe.
    20 litres of fresh fuel and check the plugs after it started playing up, I expected to find fouled plugs but didn't.
    Last edited by Oz_ek; 29-05-2021 at 08:01 PM.

  4. #4
    been here .......too long Smitty2's Avatar
    Join Date
    Mar 2007
    Location
    bayside Melbourne
    Posts
    10,044

    Default

    moisture in the cap maybe
    or old carbon leads

    did we check oil/water levels before startup?
    also the fuel filter... not gummied up?
    __________________________________
    ONE OF THE Aussie V8 MODERATOR/ADMIN TEAM

    Never late in an AussieV8!
    Club circuit racing...the best fun you can have with your pants on

  5. #5
    casual poster
    Join Date
    Jan 2017
    Location
    Melbourne
    Posts
    59

    Default

    Quote Originally Posted by Smitty2 View Post
    moisture in the cap maybe
    or old carbon leads

    did we check oil/water levels before startup?
    also the fuel filter... not gummied up?
    Water & oil are good, leads are old....Will check for moisture under cap.

    Cheers!

  6. #6
    casual poster
    Join Date
    Jul 2020
    Location
    NSW
    Posts
    131

    Default

    Corrosion in cap is my guess too.

  7. #7
    been here .......too long Smitty2's Avatar
    Join Date
    Mar 2007
    Location
    bayside Melbourne
    Posts
    10,044

    Default

    have changed the thread title from
    252 backfiring to 253 backfiring
    __________________________________
    ONE OF THE Aussie V8 MODERATOR/ADMIN TEAM

    Never late in an AussieV8!
    Club circuit racing...the best fun you can have with your pants on

  8. #8
    casual poster
    Join Date
    Jan 2017
    Location
    Melbourne
    Posts
    59

    Default

    Quote Originally Posted by Smitty2 View Post
    have changed the thread title from
    252 backfiring to 253 backfiring
    Thanks!

  9. #9
    Do you ever leave? EH179's Avatar
    Join Date
    Jan 2008
    Location
    Ipswich. QLD
    Posts
    4,391

    Default

    The fact that it started and ran for a minute would suggest the ignition components are not to blame, unless a lead or two gave up.
    Perhaps lift the rocker covers to check for broken valve springs.

  10. #10
    Senior Member
    Join Date
    Nov 2018
    Location
    Sydney
    Posts
    775

    Default

    May have also wiped a cam lobe. Sitting for a long time, all the oil drained off, dry start up.

    If the engine has headers or exh manifolds with separate exit/runner for each exh port, squirt water on each runner after a couple of minutes of warm up time. Working cyls should turn the water jet to steam, but not the dead cyl.

  11. #11
    casual poster
    Join Date
    Sep 2011
    Location
    perth
    Posts
    350

    Default

    sounds like plugs or leads or cap, plugs dont always look black to cause a misfire

  12. #12
    Do you ever leave?
    Join Date
    Jan 2017
    Location
    Nth Qld
    Posts
    1,847

    Default

    hi
    Need to isolate which cylinder is causing the problem .
    1. remove each plug lead and observe the rpm drop , cylinder that has the least drop is doing very little work .
    2 compression test dry then wet

    tune check plug lead resistance 5k--8k ohms per foot
    change points and condensor
    is the ignition timing advancing
    check cap for terminal corrosion on inside and High /Tension [plug ] terminals
    change plugs --stored vehicles hate not being driven the plugs carbon up
    look into accelerator pump ,probably not working

    bad fuel
    Last edited by swampy; 30-05-2021 at 12:42 PM.

  13. #13
    Senior Member BasicQ's Avatar
    Join Date
    Apr 2020
    Location
    Geelong
    Posts
    768

    Default

    Initial timing?

    That big cap is on properly?

    Carby got a thorough clean out?

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. vr v8 starting and backfiring
    By cozzy77 in forum Holden V8's
    Replies: 3
    Last Post: 22-05-2011, 09:09 PM
  2. Replies: 4
    Last Post: 24-10-2010, 12:46 AM
  3. ...wot causes backfiring thru the carb??
    By Smitty2 in forum Holden V8's
    Replies: 15
    Last Post: 18-10-2010, 11:19 PM
  4. Backfiring thru carb
    By RSA350 in forum Holden V8's
    Replies: 37
    Last Post: 11-09-2008, 09:32 PM
  5. XR8 backfiring on LPG
    By TroySS/AA4500 in forum Ford V8's
    Replies: 7
    Last Post: 05-11-2007, 09:56 PM

Posting Permissions

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