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.

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.