Results 1 to 3 of 3

Thread: 71 911E Engine pinging on idle

  1. 10-01-2023, 04:41 PM #1
    Stoney911
    Stoney911 is offline
    Junior Member
    Join Date
    Mar 2019
    Posts
    2

    71 911E Engine pinging on idle

    Hi, Ive seen this issue mentioned on the forums but not really any definitive answer (that Ive read)
    I have a 71 911E 2.2ltr and on idle it has a loud, random, pinging sound coming from the engine.

    Ive had the MFI rebuilt, and it has new plugs, leads, CDI and frankly runs great. It has heaps of power that it didnt before all the work was done.
    And it used to run really rich - the reason I had the MFI done, we couldn't adjust the mixture screw, and the plugs were black.

    So yesterday I took the airbox off put my synchrometer on each venturi and when it pings the suction drops off almost completely ONLY on number 3 cylinder.
    My guess is I have a sticking exhaust valve or that valve spring is broken or weak and not returning the valve to closed - thus allowing the fuel intake suction from the piston to also draw air back through the exhaust valve (reducing suction) until it slams shut again on compression and makes that loud ping.
    Is that even possible?

    Ive put some Liqui Moly cleaner in the fuel to see if that cleans the cylinder and valve stem in case its just got some residual carbon build up in there and sticking.
    And while it does does seem to be less frequent it still occurs and frankly Im not happy there's any unknown noise coming from the engine.

    Anyone had this and found the answer?

    Thanks in advance.

    Craig
    Reply With Quote Reply With Quote
  2. 10-01-2023, 05:05 PM #2
    Scott A
    Scott A is offline
    Senior Member Scott A's Avatar
    Join Date
    May 2014
    Location
    South East USA
    Posts
    914
    I wouldn’t be surprised if it’s a collapsed chain tensioner.

    Current long term ownership: 63 Cab, 71 911, 74 914
    Reply With Quote Reply With Quote
  3. 10-01-2023, 09:34 PM #3
    SFE
    SFE is offline
    Senior Member SFE's Avatar
    Join Date
    Dec 2022
    Posts
    226
    Not sure to understand exactly your problem but just in case, do you have your RPM transducer relay connected ?
    Reply With Quote Reply With Quote
« Previous Thread | Next Thread »

Posting Permissions

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

Forum Rules


Message Board Disclaimer and Terms of Use
This is a public forum. Messages posted here can be viewed by the public. The Early 911S Registry is not responsible for messages posted in its online forums, and any message will express the views of the author and not the Early 911S Registry. Use of online forums shall constitute the agreement of the user not to post anything of religious or political content, false and defamatory, inaccurate, abusive, vulgar, hateful, harassing, obscene, profane, sexually oriented, threatening, invasive of a person's privacy, or otherwise to violate the law and the further agreement of the user to be solely responsible for and hold the Early 911S Registry harmless in the event of any claim based on their message. Any viewer who finds a message objectionable should contact us immediately by email. The Early 911S Registry has the ability to remove objectionable messages and we will make every effort to do so, within a reasonable time frame, if we determine that removal is necessary.