Vintage Ford Jan-Feb

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Model T Ford Forum: Forum 2018: Vintage Ford Jan-Feb
Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, February 02, 2018 - 12:58 am:

I received the latest Vintage Ford today. I like the color pictures and the good easy to understand technical articles. There is a very good description on how to adjust new points and many other practical articles to get the T running just right for the tours coming up this year.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry & Sharon Miller, Westminster, CO on Friday, February 02, 2018 - 07:53 am:

Norm,

I agree! Another outstanding issue, packed with good information and photos.

Enjoy,
Terry


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darryl Bobzin on Friday, February 02, 2018 - 08:29 am:

Please include photos of each page so that those of us at the end of the postman's route will have nothing to look forward to when our copy arrives.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Friday, February 02, 2018 - 06:56 pm:

I agree, great Q&A tutorial by Mike Vaughn on how to adjust point cushion spring travel. Cushion spring travel is specified to be 0.005" but a person writes in about having coil points with more than twice that. Heck, I have new points that have as much as 0.025" cushion spring travel! That much travel completely defeats the entire purpose of the design; which is prevent premature firing (double sparking) and allowing coil current to ramp up to a level with enough energy to ensure a hot spark and reliable combustion. Here is data taken with adjustable cushion spring travel.

Cushion spring travel

You can see from the chart the coil current fails to increase once the cushion spring travel exceeds 0.006" which agrees very well with Ford's specification. Coil points with in excess of 0.006" cushion spring travel must be adjusted to consistently break contact abruptly and cleanly without the benefit of the limit rivet stopping the cushion spring contact travel. Finding the correct combination of vibrator spring tension, cushion spring tension and coil point gap to make that happen can be a real bear with excessive cushion spring travel. It is possible given enough time and patience as indicated by the Multi-Spark firing consistency test.

Good Firing Consistancy

The more typical result is significant random variation in coil firing time due to point arcing as the vibrator spring contact slowly pulls away from the moving cushion spring contact resulting in an electrical arc that delays firing as shown in the right photo below of coil current (y axis) versus time (x axis).

Arcing point opening

Coil point arcing causes inconsistent firing firing time on the Multi-Spark firing consistency test as illustrated below. The engine will still run but will not run smooth or with as much power compared with all 4 coils firing consistently with the same dwell time to fire. Points with the specified 0.005" cushion spring travel are much easier to adjust for equal and consistent firing time and that's why Mike's tutorial is so helpful.



Poor firing consistency


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