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FORD CYLINDER BLOCK

THE EVOLUTION OF THE MODEL A FORD CYLINDER BLOCK, A-6015

  BY

  STEVE PLUCKER

  AS OF JUNE 14, 2005

 

Have you ever discovered an engine or cylinder block where the engine serial number was either re-stamped or marked out so as not to reveal the original number?  Have you ever noticed the changes that were made in comparing cylinder blocks of different months and years?  Those of us who have been involved in this hobby most certainly have at one time or another.  I wonder how many of us have asked ourselves on what day did this particular engine get its original stamp, what was the original serial number, and when did the change take place?

 In order to answer these questions and to understand the evolution of the Model A Ford cylinder block

  

 A-6015, I set out to view as many cylinder blocks as possible (in order to come up with some type of conclusion).  As of this printing, a cross-section of 182 engines and/or cylinder blocks (that is just 0.0038% of all production cylinder blocks produced) have been observed either by myself and/or by 41 other interested persons.

 

As the last Model T Ford rolled off the assembly line on May 25, 1927, plans were already under way for the “New Ford Car”.  To make the new vehicle, it was necessary to change and redesign almost every piece of machinery used to build the old model.  After spending almost $100,000,000 in the process, the new Model A Ford made its appearance on December 2, 1927 in most of the large cities throughout the United States.

 

The Ford Motor Company completed the first of 4,830,806 production engines (October, 1927 through November, 1931) on October 20, 1927.  Over the next four years, the Model A and AA engine cylinder block, Ford Motor Company part number A-6015, went through a series of external and internal changes. To identify when some of these changes took place during the casting of the block, there was the “release and change notice” records where Ford noted the different changes to be made to the next generation of new blocks.  The “release” was an engineering document which recorded the date when the drawing was approved for production of the part.  It also recorded any changes that were made and when the part was replaced or obsolete.  The name “release” is short for “released for production”. According to the release information, it was July 1, 1927 when the first release notices were issued and continued through September 30, 1929.  Where the remaining “release and change notices” are to cover the remaining years, are unknown by the archives. 

 

Over the next four months, July to October, 1927, many aspects of the pre-production block were changed and revised into what were the first generation production blocks with the engine serial number pad located on and above the water inlet connection area on the left side of the block.  These blocks were cast and put in production up to October 12, 1927 when it was noted on the release that the size of the water inlet connection pad was to agree with the connection, A-8275, cylinder water inlet connection, and that the pad for the engine serial number was to be moved to the top of the block and reduced in size to two inches in length.  These blocks finally showed up for stamping on November 27, 1927, between engine’s # 616 and # 633.    Where a change was noted in the release notifications, it was also noted in the guide.  However not all changes noted in the release notices were listed in the guide as one can see from the guide itself.  What changes were noted in the guide were those noticeable differences in the block that were easy to view and identify.

 

To identify when these changes occurred during the serial number stamping, all we have to go by is the engine serial number itself which is located on the left side of the cylinder block on the engine serial number pad just above the cylinder water inlet port.  This number, tells us the month, day and year that the cylinder block was stamped but not necessarily when it was actually cast or installed in the car or truck.

 

Another source of identification may also appear on the engineering drawings of the cylinder block as the changes occurred.  These are at the Ford Archives.  Unfortunately, due to logistics, I was unable to go to the archives to make positive of this fact.  However, looking at the original item proved very informative.

 

Granted, the Ford Service Bulletins and the known existing copies of the Ford Service Letters tells us of some of these changes but not of all.  They were, however, usually reported about a month or so later than when the change was actually made.  The idea of the actual change most likely originated within the Ford Engineering Department a few weeks or so before the actual change was made to the part itself.  This information may be contained on the 25 or so engineering drawings of the cylinder block.

 

The goal was to see just how many types of visible changes were made to the cylinder block and try to contain each visible change within the same month of production or as close as possible.  Most of the changes are within the same month of production, however some are not.

 

Most of the data collected on each cylinder block fit nicely into the database of block changes as they were produced.  However there were several oddities and some which were out of line for one reason or the other as noted below.  The “guide” therefore, was designed off of the database.  Each change in features indicates those engine numbers which are before and after the change took place.  The numbers are according to the Ford Model A/AA Engine Number List and the numbers in parenthesis indicate the difference between the two.  Hopefully we can close in on these numbers.

 

There were instances when a new change in the block was noted BEFORE that new change became common on the assembly line of engines.  This may be due to the fact that when a group of blocks were cast, they got out of line with the others or put aside for some reason or the other, thus delaying the regular progression of the newer style blocks resulting in a mixture of old and new style blocks.  It may also be due to the slow rate of old to new castings thus the mixture of blocks as noted in the database.  When they did get back into line, the newer blocks with the newer features would eventually be the more predominant as they progressed.

 

There was a lot of variation on the engine serial number pad size within a particular pad size. The main sizes viewed were the early “shield” type and the “bar” type.  Of the “bar” type pad there werefour sizes: 2”, 2 ½”, 2 ¾” and 3 ¼”.  These sizes varied + or – 1/16” to 1/8” of an inch throughout aparticular size.  However, there was no significant difference among the sizes and the differences arecontributed to casting variations.

 

There was one cylinder block # 286,625, July 29, 1928, which must have been some type of “experimental” engine.  The block was not cast with an oil return pipe hole in the lower right side of theblock.  There were four (4) holes located between each pair of lifter holes and about the same size as thelifter holes with the front hole being slightly larger.  The oil tube inside the valve chamber ran the length ofthe block instead of the normal half block.  From this tube there were 1/8” oil holes to oil the camshaft. 

 

The valve chamber cover had no oil return hole.  Are there any more engines of this type out there?  Pleaselet me know.  According to the MARC/MAFCA Model A/AA Ford Judging Standards, “From Maythrough October, 1928 a few engines were built without an oil return pipe”.

 

Another oddity was cylinder blocks # 2,222,973 and # 2,227,666, August 28, 1929, which had at just onecorner of the oil pump pad, ½ of the shield or “extra metal” effect and the other side was of the newer stylewith no “extra metal”.  If anyone has or knows of other cylinder blocks like this, please let me know. 

 

Several features which remained the same throughout production were: 1) height of push rod bosses insidethe valve chamber; 2) front camshaft oil bearing hole; 3) height of the rear oil dam inside the valvechamber; 4) there were three oil holes in the lower oil return port.

 

I would like to thank the following people who devoted their time and patience through letters, phone callsand e-mails in contributing to this article.  Without their help, I would of never got as far as I did: FredGooding, Bill Keith, Neil Wilson, Bill Barlow, George Stoker, Ron Rude, Dan Koppinger, Andy Anderson,Terry Oberer, Dave Waddell, John Blair, H and H Machine Shop, John Mishler, Tim Kelly, CourtlandSaunders, Rick Snell, Craig Lewis, Hans “Doc” Kalinka, Willie Harms, Lyle Burnett, Ted Alkier, RickCarnegie, Tom Carnegie (Antique Auto Ranch), Larry Seemann, Rich Lorenz, Charlie Bass, Jim Brierley,Ron’s Machine Shop, Ron Hall, Hopkins Auto Ranch,  Jim Marlar (Good Old Days Garage), RogerKauffman, Don Paalman, Phil Mino, Don Gibbard, Dennis Born, Chuck Shaw, Peter Mendola, RichardAllen , Tim Mattice, Ray Stever, Tom Moniz, and Dick Burton.

 

I would also like to thank Mr. George De Angelis for his insight and willingness to share the engineeringrelease information included in this report and Mr. David Sturges for his data concerning the stampingdates of engines from the “daily engine logs” for which he got from the Ford Archives.   

 

With your help, I hope that you will check your extra engines and/or blocks (no re-stamps please) whichare lying around and contact me to help close in on these changes (and others) which occurred during theproduction of the Model A Ford.  I realize that there may be more to the story and if so, would you be sokind as to contact me, Steve C. Plucker, 12650 Touchet North Road, Touchet, Washington 99360; 509-394-2831; e-mail: pif@bmi.net , for a future update and to share with the rest of those who have an interestin this hobby.

 

       

   CYLINDER BLOCK GUIDE

       PART NUMBER A-6015

                                                                                        AS OF

                                                                                 MAY 13, 2005

 

CYLINDER BLOCK TO SPARK AND THROTTLE CONTROL ASSEMBLY CONNECTION AREA AT BACK OF CYLINDER BLOCK: GROUND “FLAT” OR WITH TWO PROTRUDING BOSSES

 

                FLAT                     # 354                       NOVEMBER 04, 1927

                TWO BOSSES # 852                       NOVEMBER 29, 1927                         (498)

                                (CONTINUE TO JANUARY-FEBRUARY, 1929)

 

 

WATER INLET PORT BAFFEL AREA BETWEEN BAFFEL AND # 3 CYLINDER

 

                LARGE GAP        # 354                       NOVEMBER 04, 1927

                SMALL GAP        # 852                       NOVEMBER 29, 1927                         (498)

                                (CONTINUE TO APRIL-MAY, 1929)

 

 

EARLY PAD TO 2” PAD SIZE (ENGINE SERIAL NUMBER PAD)

 

                EARLY                   # 616                       NOVEMBER 27, 1927

                2” PAD                  # 633                       NOVEMBER 27, 1927                         (17)

                                (CONTINUE TO DECEMBER, 1927)

 

THE  “RELEASE” INFORMATION OF OCTOBER 12, 1927, INDICATED:

·         “MOVED PAD FOR ENGINE NUMBER TO TOP OF BLOCK AND REDUCED                     SIZE”;                                                        

·         “REDUCED SIZE OF WATER OUTLET (INLET) CONNECTION PAD TO AGREE         WITH CONNECTION”;                                                            

·         “ADDED 1/32 X 45 DEG. CHAMFER ON BOTTOM OF 0.9365--0.9375 DIAMETER                REAM FOR OIL PUMP SHAFT”.

 

 

THE “RELEASE’ INFORMATION OF OCTOBER 26, 1927, INDICATED:

·         “BOSS FOR BREATHER PIPE CHANGED FROM 20 DEGREES TO 22 DEGREES”;

·         “1 INCH DIMENSION AT BOTTOM OF CYLINDER REMOVED AND 2-1/2 INCH             DIMENSION AT CENTERLINE BOSS ADDED”;

·         “23/32 INCH DIMENSION LOCATING HOLE FOR OIL PUMP DOWEL CHANGED TO          0.713--0.723 TO REDUCE VARIATION”.

 

 

2” PAD TO 2 ½” PAD SIZE (ENGINE SERIAL NUMBER PAD)

 

                2” PAD                  # 1,276                    DECEMBER 03, 1927

                2 ½” PAD       # 2,157                    DECEMBER 14, 1927                         (881)

                                (SEE BELOW)

 

 

 

 

 

 

 

THE “RELEASE” INFORMATION OF DECEMBER 5, 1927, INDICATED:

·         “ADDED 1.4335—1.4345 DIMENSION FROM CENTERLINE OF BOLT HOLES TO          REAR  THRUST FACE OF BABBITT OF REAR MAIN BEARING”;

·         “ADDED LIMITS ON DIMENSION FROM CENTERLINE OF REAR BEARING BOLT             HOLES TO CENTERLINE #4 CYLINDER OF 3.124—3.126”;         

·         “INCREASED DIAMETER OF BOSS AROUND FRONT CAMSHAFT BEARING FROM         2-1/16 INCH DIAMETER TO 2-3/8 INCH DIAMETER”;

·         “RADIUS LOCATING SIZE OF BOSS AROUND DRILLED OIL HOLE TO FRONT          CAMSHAFT BEARING CORRECTED TO READ 3/8 INCH RADIUS INSTEAD OF           ¾  INCH RADIUS”;                                                

·         “INCREASED DEPTH OF BOSSES FOR TAPPED HOLES FOR CYLINDER HEAD         STUDS FROM 1-1/8 INCH TO 1-3/16 INCH”;

·         “INCREASED DEPTH OF TAP DRILL FROM 7/8 INCH TO 15/16 INCH AND ADDED         29/64 INCH DIAMETER DRILL 1/32 INCH DEEP”;

·         “CHANGED ANGLE OF DRILLED HOLE FOR OIL LEVER INDICATOR FROM 20            DEGREES TO 22 DEGREES”.

 

 

2 ½” PAD TO 2 ¾” PAD SIZE (ENGINE SERIAL NUMBER PAD)

 

                2 ½” PAD       # 2,339                    DECEMBER 15, 1927

                2 ¾” PAD       # 4,408                    DECEMBER 27, 1927                         (2,069)

                                (CONTINUE TO FEBRUARY, 1929)

 

 

MIDDLE OIL DAM HEIGHT FROM INSIDE BASE OF VALVE CHAMBER TO TOP OF DAM

 

                1 1/16 INCHES # 25,295                  FEBRUARY 14, 1928

                1 7/16 INCHES # 45,396                  MARCH 12, 1928                  (20,101)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

 

FRONT OIL DAM HEIGHT, ABOVE OR BELOW TOP OF PUSH ROD BOSS

 

                ¼ INCH ABOVE  # 25,295                  FEBRUARY 14, 1928

                ¼ INCH BELOW# 45,396                   MARCH 12, 1928                  (20,101)

                                (CONTINUED THROUGH END OF PRODUCTION)                                                                   

THE “RELEASE” INFORMATION OF FEBRUARY 14, 1928, INDICATED:

·         “HEIGHT OF THE OIL RETAINING WALL IN OIL POCKET AT # 1                        CYLINDER INCREASED TO TOP OF PUSH ROD BOSS”;

·         “OVERFLOW HOLE THRU FRONT WALL OF POCKET LOWERED 9/16 INCH                INCREASING 1-3/16 INCH OPENING TO 1-3/4 INCH AND REDUCING 3                INCH DIMENSION TO 2-7/16 INCH”;

·         “PITCH DIAMETER ON 3/8 – 16 TAPPED HOLES CHANGED FROM 0.334—        0.339 INCH TO 0.3344—0.3389 INCH AND ON 7/16 – 14 TAPPED HOLES                (EXCEPT STUD HOLES) FROM 0.381—0.396 TO 0.3911—0.3960 INCH”.

 

 

WATER OUTLET HOLE ON TOP CENTER OF CYLINDER BLOCK

 

                ROUND                 # 41,841                  MARCH 07, 1928

                ELONGATED     # 45,396                  MARCH 12, 1928                  (3,555)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

THE “RELEASE” INFORMATION OF MARCH 15, 1928, INDICATED:

·         “CORED HOLE ON TOP OF BLOCK TO WATER PASSAGE ADDED”.

 

 

ADDITION OF TWO RE-ENFORCEMENT RIBS, “\ /” SHAPE, AT REAR MAIN BEARING

 

                NO RIBS                # 41,841                  MARCH 07, 1928

                RIBS “\  /”             # 45,396                  MARCH 12, 1928                  (3,555)

                                (CONTINUE TO JUNE, 1929)

 

THE “RELEASE” INFORMATION OF MARCH 15, 1928, INDICATED:

·         “RIBS AND METAL BETWEEN BOSSES ADDED INSIDE OF CASE AT REAR                BEARING”;

·         “BOSSES FOR FLYWHEEL HOUSING BOLTS, OIL PLUG AND ENGINE         SERIAL NUMBER REVISED”;

·         “THICKNESS OF FLANGE AT FRONT END INCREASED AND 3-3/32 R        CLEARANCE ADDED ON TWO BOSSES”;

·         “FLANGE AT FRONT AND REAR BEARINGS REVISED”;

·         “OIL FEED TUBE TO CENTER MAIN BEARING RELOCATED AND OIL                GROOVE REVISED ACCORDINGLY”.

 

 

ACCORDING TO FORD’S RECORDS OF DAILY PRODUCED ENGINES, THAT WERE ASSEMBLED BETWEEN JULY 9, 1928, (#236,787), AND OCTOBER 2, 1928, (#477,642), A NUMBER OF “SPECIAL EXPERIMENTAL” ENGINES WERE PRODUCED.   THE RETURN OIL PIPE ASSEMBLY, A-6645,  ALONG WITH THE OIL RETURN PIPE CONECTIONS ON THE BLOCK, A-6015, AND VALVE COVER CHAMBER, A-6520, WERE ALL DELETED.  THE ADDITION OF OIL RETURN HOLES WERE DRILLED ON THE FLOOR OF THE VALVE CHAMBER TO ALLOW THE OIL TO DRAIN BACK INTO THE OIL PAN.  EACH ENGINE HAD THE REGULAR MODEL A ENGINE NUMBER STAMPING TO INDICATE 1928 PRODUCTION.  BETWEEN 1353 AND 1355  ENGINES OF THIS TYPE WERE BUILT.  THESE CAN BE SUBSTANUATED BY THE “RELEASE” DATA OF APRIL 23, 1928 FOR EACH SPECIFIC PART AND THOSE FEW WHICH HAVE BEEN DOCUMENTED TODAY.   ONE ENGINE NUMBER WHICH HAS BEEN DOCUMENTED SO FAR IS #286,625 (JULY 29, 1928).  I AM SURE THERE ARE LOTS OF OTHERS.

 

ON AUGUST 27, 1928, THE “RELEASE” DATA INDICATED:

·         “OIL HOLES IN SIDE (BLOCK) AND PIPE TAPS IN ENDS OF HEADER REMOVED         AND BOSS FOR OUTSIDE OIL LINE, (A-6645), REPLACED”;

·         “BOSS FOR OIL PUMP ON BOTTOM FLANGE REDUCED TO REMOVE EXCESS         METAL” (SEE AUGUST 17, 1929 BELOW).

 

5 OR 3 CAMSHAFT BEARINGS

 

5                     # 481,204                OCTOBER 03, 1928

3                     # 492,408                OCTOBER 06, 1928                                (11,204)

(SEE FORD SERVICE BULLETIN: JANUARY, 1929)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

THE “RELEASE” INFORMATION OF SEPTEMBER 28, 1928, INDICATED:

·         “REMOVED SECOND AND FOURTH CAMSHAFT BEARINGS”.

 

 

BOTTOM OF PUSH ROD BOSSES INSIDE CRANKCASE, RAISED OR FLAT

 

                RAISED                # 763,548                DECEMBER 17, 1928

                FLAT                     # 804,976                DECEMBER 28, 1928                         (41,428)

                                (CONTINUE TO MARCH, 1930)

 

THE “RELEASE” INFORMATION OF JANUARY 10, 1929, INDICATED:

·         “PUSH ROD BOSSES ON THE UNDERSIDE OF THE BOTTOM WALL FOR         THE VALVE CHAMBER, CHANGING LENGTH OF BOSSES FROM 1-        23/32 INCHES TO 1-19/32 INCHES”;

·         “MOVED OUTER PART OF BOTTOM WALL FOR VALVE CHAMBER UP                 1/16 INCH, CHANGING DISTANCE TO BOTTOM OF BLOCK FROM                   3-15/16        INCHS TO 4 INCHES”;

·         “CHANGED ANGLE AT BOTTOM OF VALVE CHAMBER ON OUTSIDE         FROM 30 DEGREES TO 19 DEGREES”;

·         “CHANGED THICKNERSS OF BACK WALL FROM 3/16 INCH TO 7/32::9/32         INCH AND RADIUS OF OFFSET ON INSIDE FROM 2-13/16 INCH TO 2-        5/8 INCH”.

 

 

INTAKE/EXHAUST PORTS, COUNTERBORE OR NON-COUNTERBORE (FLAT)

 

                CB/CB                    # 891,720                JANUARY 17, 1929

                NCB/NCB             # 950,016                JANUARY 26, 1929                            (58,296)

                (SEE FORD SERVICE BULLETIN: JANUARY, 1929)

                                (CONTINUE TO MARCH, 1929)

 

THE “RELEASE” INFORMATION OF JANUARY 10, 1929, INDICATED:

·         “REMOVED 1.502--1.506 INCH DIAMETER COUNTERBORE FOR         MANIFOLD GLAND”.

 

 

CYLINDER BLOCK TO SPARK AND THROTTLE CONTROL ASSEMBLY CONNECTION AREA AT BACK OF CYLINDER BLOCK: WITH TWO PROTRUDING BOSSES OR GROUND “FLAT”

 

                TWO BOSSES #   988,170                FEBRUARY 01, 1929

                FLAT                     #   989,671                FEBRUARY 02, 1929                        (1,501)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

THE “RELEASE” INFORMATION OF JANUARY 10, 1929, INDICATED:

·         “CHANGED BOSSES ON THE REAR END FOR BRACKET FROM TWO         BOSSES TO ONE LONG BOSS CHANGING WALL FOR WATER JACKET         TO CORRESPOND”.

 

2 ¾” PAD TO 3 ¼” PAD SIZE (ENGINE SERIAL NUMBER PAD)

 

                2 ¾” PAD       #    975,432                JANUARY 30, 1929

                3 ¼” PAD       #    988,170                FEBRUARY 01, 1929                        (12,738)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

 

THE “RELEASE” INFORMATION OF FEBRUARY 18, 1929, INDICATED:

·         “SPECIFIED THAT CORNERS OF BABBITT IN BEARINGS BE RELIEVED WITH 1-         13/16  INCH DIAMETER OUTTER BEFORE BORING, DEPTH OF RELIEF TO BE         3/16 INCH, INSTEAD OF CHAMFERING CORNERS 1/32 X 30 DREGREES”.

 

 

INTAKE/EXHAUST PORTS, COUNTERBORE OR NON-COUNTERBORE (FLAT)

 

                NCB/NCB             # 1,187,002                MARCH 12, 1929

                NCB/CB                # 1,213,500                MARCH 18, 1929                  (26,498)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

THE “RELEASE” INFORMATION OF MARCH 13, 1929, INDICATED:

·         “ADDED 1.502--1.506 INCH DIAMETER COUNTERBORE IN EXHAUST         PORTS ONLY”.

 

 

THE “RELEASE” INFORMATION OF MARCH 28, 1929, INDICATED:

·         “CHANGED DIAMETER OF LINE REAMED HOLES FOR CAMSHAFT FROM 1.5615-         1.565  INCHES TO 1.5615--1.5625 INCHES TO REDUCE BEARING CLEARANCE”;

·          “SPECIFIED 1/32 INCH MINIMUM CHAMFER AT LOWER END OF CYLINDER         BORES TO PREVENT SCRATCHING PISTONS”.

 

 

DRILLED OIL PASSAGE HOLE FOR REAR CAMSHAFT BEARING

 

                NO HOLE     # 1,362,039                APRIL 11, 1929

                HOLE                     # 1,422,949                APRIL 19/20, 1929                             (60,910)

                (SEE FORD SERVICE BULLETIN: MAY, 1929)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

THE “RELEASE” INFORMATION OF APRIL 22, 1929, INDICATED:

·         “3/16 INCH OIL HOLE WAS ADDED TO REAR CAMSHAFT BEARING”.

 

 

WATER INLET PORT BAFFEL AREA BETWEEN BAFFEL AND # 3 CYLINDER

 

                                SMALL GAP        # 1,466,823                APRIL 28/29, 1929                                                                                             LARGE GAP        # 1,482,472                MAY 01, 1929                        (15,649)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

 

ADDITION OF MIDDLE RE-ENFORCEMENT RIB AT REAR MAIN BEARING WALL

 

                “\  /” TYPE      # 1,569,217                MAY 15, 1929

                “\ I /” TYPE      # 1,598,353                MAY 18/19, 1929                             (29,136)

                (SEE FORD SERVICE BULLETIN: JULY, 1929)

                                (CONTINUE TO JUNE-AUGUST, 1930)

 

THE “RELEASE” INFORMATION OF JULY 10, 1929, INDICATED:

·         “3/8 INCH HIGH X 3/8 INCH WIDE RIB” WAS “LOCATED IN CENTER ON         INNER FACE OF REAR WALL”.

 

 

THE “RELEASE” INFORMATION OF JULY 10, 1929, INDICATED:

·         “INCREASED HEIGHT OF RIB 17/32 INCH ON INNER FACE OF REAR WALL         LOCATED BETWEEN MAIN BEARING AND FLYWHEEL HOUSING SCREW         HOLE”;               

·          “DIMENSIONED HEIGHT 13/16 INCH FROM INNER FACE INSTEAD OF 5/8 INCH         FROM OUTER FACE”;

·         “MADE SIDES OF BOSS AROUND SCREW HOLE FLAT INSTEAD OF CURVED”;

·         “SPECIFIED HOLE TO BE TAPPED 11/16 INCH DEEP INSTEAD OF THRU”;

·         “INCREASE HEIGHT OF RIB 5/16 INCH ADJACENT TO OIL LEAD ON INNER SIDE         OF REAR WALL BY RELOCATING 1-3/4 INCH FROM CENTERLINE OF         CYLINDER #4  INSTEAD OF ¾ INCH FROM INNER FACE OF WALL”;

·         “INCREASED THICKNESS OF REAR WALL AT MAIN BEARING FROM 7/32-9/32 TO          5/16-3/8 INCH”.

 

 

EXTRA METAL RE-ENFORCMENT “SHIELD” OR NOT “HEART” AT OIL PUMP BASE

 

                SHIELD                  #2,153,966                AUGUST 17, 1929

                HEART                  #2,290,037                SEPTEMBER 11, 1929                         (136,071)

                (DURING THIS CONVERSION, SOME BLOCKS MAY HAVE ONE SIDE WITH THE

                EXTRA METAL AND THE OTHER SIDE WITHOUT THE EXTRA METAL AS SEEN WITH

                # 2,222,973 AND 2,227,666, BOTH AUGUST 28, 1929 STAMPINGS)

                                (SEE “RELEASE” INFORMATION FOR AUGUST 27, 1928 ABOVE)       

                                (CONTINUED THROUGH END OF PRODUCTION)

 

 

THE “RELEASE” INFORMATION OF SEPTEMBER 30, 1929, INDICATED:

·         “CANGED POSITION OF RIB BETWEEN MAIN BEARING AND FLYWHEEL         HOUSING SCREW HOLE (ON INNER FACE OF REAR WALL) BY SHIFTING         LOCATING POINT AT BOTTOM OF RIB FROM CENTER OF MAIN BEARING TO         9/16 INCH OFF VERTICAL CENTERLINE”;

·         “REMOVED ANGLES FORMING BOSS AT TOP OF RIB, REPLACING WITH 7/16         INCH RADIUS”;

·         “CHANGED HEIGHT OF RIB FROM 13/16 INCH TO 11/16-3/4 INCH”;

·         “CHANGED THICKNESS OF REAR WALL AT MAIN BEARING FROM 5/16-3/8 INCH         TO 9/32-11/32 INCH”.

 

THERE WERE NO OTHER KNOWN “RELEASES” CONCERNING THE MODEL A/AA ENGINE BLOCK, A-6015, AFTER SEPTEMBER 30, 1929.

 

 

BOTTOM OF PUSH ROD BOSSES INSIDE CRANKCASE, FLAT OR COUNTERSUNK

 

                FLAT                     # 2,972,380                MARCH 08, 1930

                COUNTERSNK   # 3,056,141                MARCH 29, 1930                  (83,761)

                                (CONTINUE TO MAY, 1930)

 

 

BOTTOM OF PUSH ROD BOSSES INSIDE CRANKCASE, COUNTERSUNK OR FLAT

 

                COUNTERSNK   # 3,481,035                MAY 25/26, 1930

                FLAT                     # 3,506,256                MAY 29, 1930                                        (25,221)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

 

RE-ENFORCEMENT RIBS AT REAR MAIN BEARING WALL BECOME PARLELL

 

                “\ I /” TYPE      # 3,790,621                AUGUST 06, 1930

                “I I I” TYPE      # 3,792,191                AUGUST 06, 1930                              (1,570)

                                (CONTINUED THROUGH END OF PRODUCTION)

 

 

“OLD” STYLE SERIAL NUMBERS TO “NEW” STYLE SERIAL NUMBERS (1, 6, AND 9)

 

                OLD                        # 4,299,173                JANUARY 27, 1931

                NEW                      # 4,307,001                JANUARY 28, 1931                            (7,828)

                (SEE FORD SERVICE BULLETIN: FEBRUARY, 1931)

 

                (MARC/MAFCA JUDGING STANDARDS RELATE THIS CHANGE WAS IN MARCH, 1931)

 

(THE APRIL 10, 1931 CHICAGO ASSEMBLY PLANT’S FORD SERVICE LETTERS

INDICATE “THIS REVISED STAMPING OF FIGURES ONE, SIX, AND NINE WILL BE STARTED WITH ENGINE NO. 4,365,834”.  THIS IS A FEBRUARY 18, 1931 STAMPING)

 

(THERE WAS A LATE “FRAME” WITH ENGINE NUMBER 4,307,001 THAT HAD THE                                              “NEW” NUMBER “1” STAMPED IN THE FRAME.  THIS WAS A JANUARY, 1931                                  STAMPING)

                                (CONTINUED THROUGH END OF PRODUCTION)