Magneto Timing Segments

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Model T Ford Forum: Forum 2016: Magneto Timing Segments
Top of pagePrevious messageNext messageBottom of page Link to this message  By Wendell Gallagher on Thursday, July 07, 2016 - 11:42 am:

I was a little confused between magneto and battery timing.

After searching the forum, I found my answer... the magneto has four timing "segments" and the battery is proportional.

Is this correct?

https://youtu.be/jq65RqwPusw


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Dufault on Thursday, July 07, 2016 - 11:57 am:

try this for an explanation...

http://www.mtfca.com/encyclo/Ignition.pdf

Is this something you already found?

PS you might like this thread:
http://www.mtfca.com/discus/messages/179374/242755.html?1319473188

(Sorry - you may have to copy and paste that last link into yoour browser...it does not appear to be a "live" link).

If not, let us know...

(Message edited by adave on July 07, 2016)

(Message edited by adave on July 07, 2016)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wendell Gallagher on Thursday, July 07, 2016 - 12:04 pm:

Thanks, Dave!

The search function on this site is terrible.

I've found it more useful to Google my question and then back-link to the forum :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Dufault on Thursday, July 07, 2016 - 12:20 pm:

Agreed - the search function leaves things to be desired...

However...

despite the lack of heaters and air conditioning (and CD players, etc), in most of our Model T's, we hold them in affectionate regard.

Some of use have great success in using the Google search for the questions - as you do - BUT - after the question put the letters mtfca in the search box, and google will find the Forum answers quite nicely.

Enjoy that Speedster...looks very nice!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Zachary Dillinger - Charlotte, MI on Thursday, July 07, 2016 - 12:43 pm:

I use google to search this page directly. Type site:mtfca.com "whatever you are looking for" in Google and it will only find results on mtfca.com. It is Boolean which is handy.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Thursday, July 07, 2016 - 03:33 pm:

When operating on battery the points vibrate continuously while the timer is making contact. This causes accelerated point wear. The coil was designed to operate on AC voltage. Operating on DC is a crutch, not what you want to do normally.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wendell Gallagher on Friday, July 08, 2016 - 12:33 pm:

That makes sense, Royce.
Were the earlier cars magneto only?
(mine is a 22')


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Friday, July 08, 2016 - 01:26 pm:

Unfortunately Wendell, its often easy to get confused or mislead on this forum because of the misinformation that is conveyed as authoritative fact.

Coil points wear regardless if operating from AC or DC battery. The fact is, Model T engine performance operating from 12V battery functions as good or better than magneto operation. Here is the actual measured data taken using professionally rebuilt and adjusted coils and a specially designed data acquisition system that recorded the vehicle speed and engine RPM of each run.

Be skeptical of the frequent unsubstantiated claims made on this forum. Many are made by ill-informed participants or skewed by personal bias for whatever reason. Solid measured data does not lie!

12V vs 6V vs Mag


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wendell Gallagher on Friday, July 08, 2016 - 01:38 pm:

Mike, I think Royce's meaning was that points wear more when using DC. It makes sense to me that the points should wear less on AC because they will only vibrate on the "pulse" and not the entire grounding phase of the timer... am I missing something?

(edit: performance wasn't being discussed, but your graph is interesting)

(Message edited by windy on July 08, 2016)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Friday, July 08, 2016 - 01:42 pm:

Wendell,

You read and understood what I quoted from Ron Patterson and Steve Conniff's article perfectly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, July 08, 2016 - 04:31 pm:

Mike, would you explain what that chart means?

I don't know what MagV means or MagR What is 12v VV or 12v R or 6v R.

I see that all the V 's line up and all the R's line up, but don't know what they mean.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Friday, July 08, 2016 - 04:35 pm:

Wendel, I'm not aware of any data that suggests or proves accelerated point contact wear occurs when operating on DC with respect to operating on AC magneto.

The situation is not as simple as as buzzing continuously on DC versus intermittently on AC. The polarity of current remains fixed operating on DC so there is greater possibility of metal migration/plating from one point contact to the other but the voltage is low compared with magneto operation and the actual number of times the coil buzzes is limited by the duration the timer remains on contact at normal engine speeds (assuming you don't leave the ignition on with timer on contact for any significant duration of course); If coil spark frequency is about 3ms that means between 2 to 8 coil firings per timer contact at engine speeds of 600 to 2000 RPM as opposed to up to 4 coil firings per timer contact operating on magneto over the same RPM range. Another significant variable is the fact the magneto voltage pulses can reach a peak voltage of about 70V.

I provided the data on engine performance operating on 12V DC battery in response to the inference that Model T engine performance "operating on DC is a crutch", it most certainly is not with properly adjusted coils.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Kossor - Kenilworth, NJ on Friday, July 08, 2016 - 06:01 pm:

Norman, My apology; Sure.

PRO = Professionally rebuilt and adjusted coil
MagV = Magneto operation, Velocity
12VV = 12V battery operation, Velocity
6VV = 6V battery operation, Velocity
MagR = Magneto operation, Engine RPM
12VR = 12V battery operation, Engine RPM
16VR = 6V battery operation, Engine RPM

The chart shows vehicle speed (on the left axis) and Engine RPM (on the right axis) versus time on the horizontal axis on the bottom.

The car started from the same point on the same course at time 0 for each test run. You can see the engine RPM reve up and shift from low to high at time 8.3 seconds (note the circle around the red, orange and purple traces pointing to the right axis which are the units to use for those traces) Engine RPM get up to just about 2300RPM in all cases but the 6V battery case, then falls to about 1100 RPM as high gear engages and slowly rises with time as vehicle speed increases.

Vehicle speed versus time is read on the right axis. The coils operating from 12V battery trace is line on line with the coils operating on magneto trace indicating the vehicle accelerates equally to the same speed with time; reaching a top speed of 34MPH at time 28.5 seconds. Note that the course was on a slight incline.


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