400i Ignition and Cam timing info | FerrariChat

400i Ignition and Cam timing info

Discussion in '365 GT4 2+2/400/412' started by Piston.Broke, Apr 24, 2021.

  1. Piston.Broke

    Piston.Broke Karting

    Mar 5, 2009
    Full Name:
    Camshaft timing and ignition timing check on the 400i.
    I removed the distributor to check that the fly weights (for high rev ignition advance) were working properly. The distributor was easy to remove and dissassemble, so that you can check and lubricate the centrifigal fly weights in the base of the distributor. Once this was done I set the ignition timing (staticly) using the 8 deg advance mark on the flex plate. (This is done from under the car, so it helps to have a car lift available).
    Be advised that even though the 400i uses a single distributor and coil for ignition, it still has timing marks for A bank and B bank on the flexplate (My car is an Auto).
    This is an issue as when I first set up the distributor with the lower peg of the rotor set to No.1 spark plug (there is an index mark for this on the distributor body) I thought (incorrectly) that the timing was all set to go. But no, she wouldnt fire. Back under the car again to check the timing marks and guess what - yes, there are two sets of ignition timing marks! This must be a hang over from the earlier cars which utilised 2 distributors and 2 coils, both with slightly different timing requirements.
    So, for a 400i make sure you use the timing mark AF 8 deg marked as A bank.

    It was relatively easy to simply set it on the correct mark at AF 8 deg and then pull the distributor and re-set it in the drive splines so the rotor was once again pointing at No.1 (use the ref mark on the distributor body for this).
    Once this was done, I removed both cam chain covers to check the camshaft timing.
    Again, this is not difficult to do, provided you take your time. On the RHS cam chain cover you do have to remove the vacuum pump and the Oil filler. You will also have to release the Oil dipstick to allow the RHS cover to come off. You will also have to remove both fuel injection warm up regulators but these can be moved to the side whilst keeping the fuel lines undisturbed.
    At this point, (as I dont have a dial gauge) I just wanted to check that the cam timing marks looked OK with No.1 cylinder at Top Dead Center (TDC). A number of owners have reported that the relatively long chain drive to the cams can stretch over time and disturb the cam timing. It is very important when doing this to make sure that No. 1 Cylinder is on its compression stroke and that it is set at TDC. As I was working on my own, I simply set up a compression tester in No.1 Cylinder and used the starter to turn the car over until I got the start of compression pressure indictaing in No.1 Cylinder. After this I got under the car again and set the timing marks on the flex plate (set at the factory) to PM 1 6. This indicates TDC for both cylinders 1 and 6. (I think in Italian the PM represents 'Punto Morte' meaning 'Dead Point' - same as TDC).
    Once this was done, it was back up top to view the cam timing marks and see how far out they might be. Well, amazingly, they all apeared to be within 1 or 2 deg of the factory timing mark except for Cam No.3 which (ofcourse) has absolutely no timing marks on it at all !!
    As all the other cams look good and seem to be timed correctly, I will leave well enough alone and assume that No.3 cam is set up properly. (I assume that No.3 cam may have been replaced prior to my ownership and that it wasnt marked up after installation).
    In a couple of days, she goes all back together and hopefully all will be well.
    I hope this info has been helpful, as although I have had my 400i for around 15 years - I havent really delved into the mechanicals very much in the past.
    raemin likes this.
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  3. ricar116

    ricar116 Formula Junior

    Aug 2, 2005
    Bolivar, Missouri
    Full Name:
    Rick Carr
    Good stuff. Thank you for sharing!

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