Page 1 of 2 12 LastLast
Results 1 to 10 of 17

Thread: Ignition timing & idle

  1. #1
    Join Date
    May 2019
    Location
    Italia
    Posts
    7
    Total Downloaded
    0

    Ignition timing & idle

    Hi everyone, I have a range rgover classic with 3.9 v8 rebuilt with a kent cam h 180 ... new oem stepper motor and I have no air leaks in the plenum chamber, rover pressure gauge has no fault code, my problem is in the gear shift, when the clutch is released with little gas the engine accelerates revolutions per minute 1200-1500, or stopping at an intersection before descending to 700 rpm takes about 3 seconds. I have setting the idle but i have a small difference... i have setting high timing ignotion 19° i think is the causes.... whow do you think?

  2. #2
    Join Date
    May 2003
    Location
    On The Road
    Posts
    29,830
    Total Downloaded
    0
    I have the same cam,, but try the advance at 10-12...
    I thought the slow engine wind down was a pollution thing?
    "How long since you've visited The Good Oil?"

    '93 V8 Rossi
    '97 to '07. sold.
    '01 V8 D2
    '06 to 10. written off.
    '03 4.6 V8 HSE D2a with Tornado ECM
    '10 to '21
    '16.5 RRS SDV8
    '21 to Infinity and Beyond!


    1988 Isuzu Bus. V10 15L NA Diesel
    Home is where you park it..

    [IMG][/IMG]

  3. #3
    Join Date
    May 2019
    Location
    Italia
    Posts
    7
    Total Downloaded
    0
    I hadn't thought about pollution, so it could be a characteristic of the cam

  4. #4
    Join Date
    Jan 1970
    Location
    Avoca Beach
    Posts
    13,981
    Total Downloaded
    0
    If the car is moving and foot off accelerator , the stepper motor will raise the revs to about 1200 until you stop.

    The formula in the ECU is speed signal positive +Throttle position sensor less that 0.49 volts ( ie foot off accelerator) + revs less than 1500 then the stepper will raise revs to 1200.

    It is primarily to give a smooth shift to 1 in an auto, but AFAIK they fitted it to manuals as well.
    It is normal but exaggerated by your incredible static timing. Reduce the timing to 10degrees BTDC. You maybe should also check that the centrifugal advance is moving freely and maybe oil the shaft under the rotor if you haven't done so.
    Regards Philip A

  5. #5
    Join Date
    May 2019
    Location
    Italia
    Posts
    7
    Total Downloaded
    0
    I can't keep the times at 10 ° because I would have no performance....the rotating masses are lubricated but compared to another distributor the springs are harder, could this be the cause?

  6. #6
    Join Date
    May 2013
    Location
    Bittern Vic
    Posts
    516
    Total Downloaded
    0
    When setting a distributor timing there are three settings to check
    1 Initial timing.
    2 Amount of timing advance when the revolutions are increased
    3 Vacuum advance when the vacuum pot is given vacuum

    You need a timing light with and advance dial to check a distributor properly and check all three settings

    The other item to check is to ensure that o degrees is actually zero and the piton is at top dead center.

    I am not sure of the specifications of a rover V8 distributor but most engines run something around 8 deg initiial and total advance of 36 deg
    Vacuum advance can be around 8 degrees and vac advance was normally used on with automatic transmissions in the old days.

    The advance weights in your distributor can become stuck or may have been set incorrectly. If you are lucky you may find someone with a distributor checking machine available in your area.

    Sorry to confuse the issue.

    Ian
    Bittern

  7. #7
    Join Date
    May 2019
    Location
    Italia
    Posts
    7
    Total Downloaded
    0
    Thank you for your tips!

  8. #8
    Join Date
    Mar 2007
    Location
    Canada
    Posts
    1,013
    Total Downloaded
    0
    Yes. If you are needing to force the static timing to get performance your distributor is not working properly. You can determine the timing curve with a timing gun by increasing the engine speed.

  9. #9
    Join Date
    Jan 1970
    Location
    NSW far north coast
    Posts
    17,279
    Total Downloaded
    0
    Quote Originally Posted by Red90 View Post
    Yes. If you are needing to force the static timing to get performance your distributor is not working properly. You can determine the timing curve with a timing gun by increasing the engine speed.
    Or the curve isn't correct for the cam/compression/chamber shape/fuel.
    But as say, you can determine what you have with a timing light.

  10. #10
    Join Date
    Mar 2007
    Location
    Canada
    Posts
    1,013
    Total Downloaded
    0
    Quote Originally Posted by rick130 View Post
    Or the curve isn't correct for the cam/compression/chamber shape/fuel.
    But as say, you can determine what you have with a timing light.
    I don’t think these ancient engines care much about the timing curve. But a broken centrifugal advance would cause these symptoms.

Page 1 of 2 12 LastLast

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!