The Ford Barn

H. L. Chauvin · 06-26-2013, 11:05 PM

This may only interest those trying to run Model A vehicles with Model B distributors & trying to set the timing with a timing pin inserted in a Model A timing gear. Also may it not interest anyone!

FWIW: QUIZ:

1. Quite a few threads have been written over the years with repeated detailed information & specifications on how to adjust the ignition timing for a Model B centrifugal advance distributor installed on a Model A engine while using a Model A timing cover., i.e., so many specified degrees advanced BTDC.

2. If anyone is into simple geometry, & has a pencil, a few straight edges, & a protractor, this would be an "eye-opening" experiment to compare the angle & location of the timing pin on a Model A timing cover with the angle & location of the timing pin on a Model B timing cover. The answer is in the difference between these two timing cover timing pin location angles.

3. One way to get started is draw a horizontal line on a blank sheet of paper about 18" long. (This will be the base line to align the flat, horizontal bottom of both timing covers, i.e., where they contact the oil pan when installed on an engine.)

4. Next, align & set one individual timing cover on this line at a time & draw a continuous second line at an angle intersecting the center of the embossed protruding part of the timing cover in front of the cam plunger & the center of the timing pin hole, & then extend this line down to the aforementioned base line.

5. After measuring the angles of each individual different timing pin hole angles from the horizontal base line, one will find that the angle of the timing pin indentations on each cam shaft will differ.

6. One can now see that rising from right to left from the front center of the timing gear, the Model A camshaft indentation occurs at approximately 17.5 degrees from the horizontal; however, rising again from right to left from the center of the timing gear, the Model B indentation occurs at approximately 25 degrees from the horizontal; hence, the Model B timing pin indentation on the timing gear is 7.5 degrees closer to say the 12:00 o'clock timing gear mark than that of the Model A.

7. Now, taking into consideration that the timing gear makes two (2) revolutions for every crankshaft revolution, & the rotor makes one (1) revolution for every two (2) crankshaft revolutions:

A. Can anyone guess how many degrees one has to advance the crankshaft timing when using a Model B distributor in conjunction with setting the timing while using a timing pin in a Model a timing cover?

B. Can anyone guess how far, say in fractions of an inch, the metal part of the rotor would have to advance CCW with respect to the distributor body's no. 1 contact point when using a Model B distributor timed with a timing pin in a Model A timing cover, that is "after" the above testing of the actual angles on different timing covers?

8. We did it years ago with no problems.

Cockshutt Kid · 06-27-2013, 05:22 AM

Ok.

Cockshutt Kid · 06-27-2013, 05:31 AM

You guy's have me totally confused now. The model B cam is ground differently for higher lift. The timing cover has a different timing pin location. The distributor has mechanical advance. But is Top Dead Centre not always the same? What is the difference here? Is the cam referrenced differently to the timing gear, is the timing gear different, is top dead centre not the starting point on both engines? What gives? Thanks.

Mike V. Florida · 06-27-2013, 06:57 AM

The Model B has an automatic centrifugal advance mechanism designed into it thius the need for different initial timing.

Look here,

http://www.fordgarage.com/pages/bdistributordetails.htm

H. L. Chauvin · 06-27-2013, 08:10 AM

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Hi Mike,

Agree, wonderful photos of a Model B distributor, & agree that a "different" initial timing is required; but, what about the questions on "how much" BTDC?

Hint:

1. Someone "wisely" posted that if one advances the timing with the "how much" already posted on this Forum, one should never "hand crank" a Model A or Model B engine with a Model B distributor because of possibly breaking an arm -- with 19 degrees BTDC I think he was "correct".

2. Rather than continuing to try this recommended "how much" BTDC, try this nineteen (19) degrees BTDC as an experiment to see what happens.

3. Also, be aware that Ford supplied a crank with "every" Model B vehicle to be "safely" used in an emergency if the battery was low or dead.

4. After very recently trying the "how much" BTDC posted, & in experiencing & remembering seeing quite a few properly timed B engines & A engines with Model B distributors years ago that were hand cranked very often with no broken arms, I thought about comparing timing covers.

06-26-2013, 11:05 PM	#1
H. L. Chauvin Senior Member Join Date: May 2010 Posts: 4,179	Model B Distributor Used with a Model A Timing Cover This may only interest those trying to run Model A vehicles with Model B distributors & trying to set the timing with a timing pin inserted in a Model A timing gear. Also may it not interest anyone! FWIW: QUIZ: 1. Quite a few threads have been written over the years with repeated detailed information & specifications on how to adjust the ignition timing for a Model B centrifugal advance distributor installed on a Model A engine while using a Model A timing cover., i.e., so many specified degrees advanced BTDC. 2. If anyone is into simple geometry, & has a pencil, a few straight edges, & a protractor, this would be an "eye-opening" experiment to compare the angle & location of the timing pin on a Model A timing cover with the angle & location of the timing pin on a Model B timing cover. The answer is in the difference between these two timing cover timing pin location angles. 3. One way to get started is draw a horizontal line on a blank sheet of paper about 18" long. (This will be the base line to align the flat, horizontal bottom of both timing covers, i.e., where they contact the oil pan when installed on an engine.) 4. Next, align & set one individual timing cover on this line at a time & draw a continuous second line at an angle intersecting the center of the embossed protruding part of the timing cover in front of the cam plunger & the center of the timing pin hole, & then extend this line down to the aforementioned base line. 5. After measuring the angles of each individual different timing pin hole angles from the horizontal base line, one will find that the angle of the timing pin indentations on each cam shaft will differ. 6. One can now see that rising from right to left from the front center of the timing gear, the Model A camshaft indentation occurs at approximately 17.5 degrees from the horizontal; however, rising again from right to left from the center of the timing gear, the Model B indentation occurs at approximately 25 degrees from the horizontal; hence, the Model B timing pin indentation on the timing gear is 7.5 degrees closer to say the 12:00 o'clock timing gear mark than that of the Model A. 7. Now, taking into consideration that the timing gear makes two (2) revolutions for every crankshaft revolution, & the rotor makes one (1) revolution for every two (2) crankshaft revolutions: A. Can anyone guess how many degrees one has to advance the crankshaft timing when using a Model B distributor in conjunction with setting the timing while using a timing pin in a Model a timing cover? B. Can anyone guess how far, say in fractions of an inch, the metal part of the rotor would have to advance CCW with respect to the distributor body's no. 1 contact point when using a Model B distributor timed with a timing pin in a Model A timing cover, that is "after" the above testing of the actual angles on different timing covers? 8. We did it years ago with no problems.

06-27-2013, 05:22 AM	#2
Cockshutt Kid Member Join Date: May 2013 Location: Ontario, Canada Posts: 81	Re: Model B Distributor Used with a Model A Timing Cover Ok.

06-27-2013, 05:31 AM	#3
Cockshutt Kid Member Join Date: May 2013 Location: Ontario, Canada Posts: 81	Re: Model B Distributor Used with a Model A Timing Cover You guy's have me totally confused now. The model B cam is ground differently for higher lift. The timing cover has a different timing pin location. The distributor has mechanical advance. But is Top Dead Centre not always the same? What is the difference here? Is the cam referrenced differently to the timing gear, is the timing gear different, is top dead centre not the starting point on both engines? What gives? Thanks.

06-27-2013, 06:57 AM	#4
Mike V. Florida Senior Member Join Date: May 2010 Location: South Florida Posts: 14,054	Re: Model B Distributor Used with a Model A Timing Cover The Model B has an automatic centrifugal advance mechanism designed into it thius the need for different initial timing. Look here, http://www.fordgarage.com/pages/bdistributordetails.htm __________________ What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II

06-27-2013, 08:10 AM	#5
H. L. Chauvin Senior Member Join Date: May 2010 Posts: 4,179	Re: Model B Distributor Used with a Model A Timing Cover Sponsored Links (Register now to hide all advertisements) Hi Mike, Agree, wonderful photos of a Model B distributor, & agree that a "different" initial timing is required; but, what about the questions on "how much" BTDC? Hint: 1. Someone "wisely" posted that if one advances the timing with the "how much" already posted on this Forum, one should never "hand crank" a Model A or Model B engine with a Model B distributor because of possibly breaking an arm -- with 19 degrees BTDC I think he was "correct". 2. Rather than continuing to try this recommended "how much" BTDC, try this nineteen (19) degrees BTDC as an experiment to see what happens. 3. Also, be aware that Ford supplied a crank with "every" Model B vehicle to be "safely" used in an emergency if the battery was low or dead. 4. After very recently trying the "how much" BTDC posted, & in experiencing & remembering seeing quite a few properly timed B engines & A engines with Model B distributors years ago that were hand cranked very often with no broken arms, I thought about comparing timing covers.