Question for clarity on Ignition timing

ValVal Posts: 907Member
in "How To" - Skills, mechanical and other wise
If anyone can please tell me about how they set the ignition timing in their late 1930s cars. I have been doing it and always set the pointer in the middle between the mark on the fly wheel (as shown in the picture) but I read that  "Timing  is 5 degrees before topdead center. First on flywheel ahead of "U.D.C. 1-6" should register pointer at flywheel inspection hole." 
So AM I to take that as I should put the pointer in line with the mark closest to the U.D.C 1-6 ?  Or is where I have it set acceptable?

Comments

  • GeoffGeoff Posts: 4,136Senior Contributor
    Set it to the first mark with a timing light at idle.
  • ValVal Posts: 907Member
    Geoff, by first mark you mean the one closest to the 1-6?
  • terraplane8terraplane8 Posts: 553Senior Contributor
    I like using a vacuum gauge, push its rubber pipe in to the wiper vacuum port on the inlet manifold then adjust the mixture and timing to get the highest reading. For the timing I get the maximum vacuum at idle then back it off a little by up to 1lb. I have got a thread on here from a few years ago discussing that. Works very well. In the old days they road tested and listened for pinging when flooring the throttle at low speed in top, backing off the timing until the sound was no longer heard. After vacuum gauge timing my 212 engine I heard no pinging at all and that is with good compression too, around 7.3:1. I didn't correlate that back to what that then showed on the timing marks, there was no need, but it would be interesting to know nevertheless.
  • GeoffGeoff Posts: 4,136Senior Contributor
    The right hand mark, which is the first one that comes into view..
  • Old Fogey UKOld Fogey UK Posts: 596Expert Adviser
    Geoff Moore, the technical guru of the ROC, advises for 8 cylinder engines  that the timing should be set to the maximum advance mark which is 3/4" before top dead centre to cope with modern fuel.
    Would our own resident Wise Old Owl (aka Geoff 😉) concur with that ?
  • Old Fogey UKOld Fogey UK Posts: 596Expert Adviser
    I forgot  to mention  that the ROC says that 3/4" before TDC means the longer leg of the H mark, i.e. the right leg of the H.
  • JACK356JACK356 Posts: 142Member
    edited April 5
    Intéressant étant donné que je dois poser le briquet sur mon  34.Ca  fait combien de degrés avant le PMH avec le stroboscope? Merci

    ps      8 CYLINDRES
  • Old Fogey UKOld Fogey UK Posts: 596Expert Adviser
    JACK356 said:
    Intéressant étant donné que je dois poser le briquet sur mon  34.Ca  fait combien de degrés avant le PMH avec le stroboscope? Merci

    ps      8 CYLINDRES
    Jacky - I will be timing my engine this way next week and I will send you an email to answer your question.
    Cheers, David.
  • JACK356JACK356 Posts: 142Member
    Thank you :)
  • ValVal Posts: 907Member
    Thanks all, the good doctor says where I have it is good
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