Model A & B Style

Ford Garage

Cast Iron Cylinder Head Compression Ratios

A variety of cylinder heads and compression ratios have been made for the Model A and B (& G28T) style engines over the years by Ford globally, as well as by aftermarket producers.

The original Model A Ford compression ratio was 4.2 to 1, which is quite low by most standards. Other cars of that era typically had ratios in the 5-6 to 1 range. Since that time there have been numerous aftermarket heads made having increased compression ratios, more power, and better performance.

Higher compression ratios can also result in better cooling (compared to lower CR) despite higher combustion chamber pressures and temperatures at the same speeds and loads. Higher ratio heads tend to run cooler because more of the fuel energy is converted into power, and less into heat at those higher ratios.

Summarized below is a list of cast iron cylinder heads and their combustion chamber shapes and compression ratios for a variety of original applications from 1928 through the mid 1950s, as well as a few more recent examples.

Heads highlighted below in green are the most useful heads to look for. Inspect carefully for cracks and damage at water openings, head stud holes, and in spark plug threads.

Model A Cast Iron Cylinder Heads:
(Four-stud Water Pump Provision)

Part Number
or Marking
Description Combustion
Chamber
Shape
Combustion
Chamber
Volume (cc)
Published
Compression
Ratio
A-6050-A Ford USA, Global
1928-31 Standard Production head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves

Also produced by Ford Canada, Ford England, and Ford Köln Germany
Wedge 242-248 4.2 :1
A-6050-B Ford USA
1931 Production High Compression "Police" head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves
Marked with a large "B" on top

Buyer Beware:
Prone to cracking. Inspect carefully.


Can use a Model B head gasket on a Model A block
Heart 178-184 5.2 :1
AF-6050 Ford Dagenham England, 14.9 HP (R.A.C.)
1928-31 Standard Production 3 inch bore head
Model A, 4 stud water pump
This head was produced by Ford England for the 2.2L 14.9 HP (R.A.C.) Model AF engine
? 144-150 ? :1
F1 MF 1930s aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves
Marked "F1", "MF", and "Made in USA" on top

Copy of Model A Ford combustion chamber
Wedge 242-248 4.2 :1
A6050A 1940s aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves
Marked "A6050A" and "Made in USA" on top

Copy of standard production Model A Ford combustion chamber
Wedge 242-248 4.2 :1
B6050
Speed Head
Variation 1
1930s aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves
Marked "B6050 Speed Head" on top

Buyer Beware:
Though marked "B6050 Speed Head" on top, this head is actually a total copy of a standard production Model A Ford (4.2) wedge combustion chamber and head,
not a higher compression (5.2) A-6050-B or (4.6) B-6050 Ford head.

The Variation 2 of this head marked "B6050 Speed Head" has the Model B (4.6) combustion chamber, but also has the Model A 4 stud water pump provisions

Copy of standard production Model A Ford combustion chamber
Wedge 242-248 4.2 :1
B6050
Speed Head
Variation 2
Early 1930s aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves
Marked "B6050 Speed Head" on top

Buyer Beware:
This head is a copy of the standard Model B Ford B-6050 (4.6) combustion chamber
, combined with the four stud Model A water pump provisions.

Copy of standard production Model B Ford combustion chamber

Can use a Model B head gasket on a Model A block
Heart 210-216 4.6 :1
A6050B
Speed Head
Late 1930s aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves
Marked "A6050B Speed Head" and "S-S" on top

Copy of Model A Ford A-6050-B "Police" head

Can use a Model B head gasket on a Model A block
Heart 178-184 5.2 :1
Model A 1930s (?) aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves
Marked "Model A" on water hump in raised letters
No other markings or date codes

Copy of Model A Ford A-6050-B "Police" head

Can use a Model B head gasket on a Model A block
Heart 178-184 5.2 :1
F2 MF 1930s aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves
Marked "F2", "MF", and "Made in USA" on top

Copy of Model A Ford A-6050-B "Police" head

Can use a Model B head gasket on a Model A block
Heart 178-184 5.2 :1
Simmons Simmons Super Power Head
1930s era aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, located between valves
Marked "Simmons Super Power Head" on water hump in raised letters, and "Licensed by Chrysler Motors" on top
Ricardo
Crowfoot
5.5 :1
Snyders Modern aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves

Similar to Model A Ford "Police" head

Uses a Model B head gasket
Heart 5.5 :1
B-F 5.9 Brumfield Regular Head
1985-2005 aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves
Marked "B-F" on top

Larry Brumfield design combustion chamber

Uses a Fel-Pro 7013 head gasket
Modified
Heart
5.9 :1
Snyders Modern aftermarket head
Model A, 4 stud water pump
Inch 7/8-18 spark plugs, over intake valves

Originals used Bill Stipe design combustion chamber, produced for Snyders by Tod Buttermore

Uses a Model B head gasket
Rounded
Modified
Heart
152 6.0 :1
Buttermore
Winfield
Modern aftermarket Winfield head
Model A, 4 stud water pump

Winfield design combustion chamber, modified by Tod Buttermore

Uses a Model B head gasket
Modified
Winfield
6.0 :1
Winfield Winfield "Yellow Head"
1930s-40s era aftermarket head
Model A, 4 stud water pump
Early heads used Metric 18mm spark plugs,
Later heads used Metric 14mm spark plugs,
Spark plugs located between valves
Marked "Winfield" on water hump in recessed letters
Winfield
Standard &
Crowfoot
6.0 :1
Winfield Winfield "Red Head"
1930s-40s era aftermarket head
Model A, 4 stud water pump
Early heads used Metric 18mm spark plugs,
Later heads used Metric 14mm spark plugs,
Spark plugs located between valves
Marked "Winfield" on water hump in recessed letters
Winfield
Crowfoot
7.0 :1
Super Winfield Super Winfield "Red Head"
1930s-40s era aftermarket head
Model A, 4 stud water pump
Metric 14mm spark plugs, located between valves
Marked "Super Winfield" on water hump in recessed letters
Winfield
Standard
7.0 :1
B-F Super Super Brumfield
1985-2005 aftermarket head
Model A, 4 stud water pump
Metric 14mm spark plugs, over intake valves
Marked "B-F" on top

Larry Brumfield design combustion chamber

Uses a Fel-Pro 7013 head gasket
Modified
Heart
7.0 :1

Model B & G28T Cast Iron Cylinder Heads:
(Three-bolt Water Pump Provision)

Part Number
or Marking
Description Combustion
Chamber
Shape
Combustion
Chamber
Volume (cc)
Published
Compression
Ratio
B-6050 Ford USA, Global
1932-38 Standard Production head
Model B, 3 bolt water pump
Inch 7/8-18 spark plugs, over intake valves
Marked with a large "C" on top

Also produced by Ford Canada, Ford England,
Ford Köln Germany, and Ford GAZ Russia
Heart 210-216 4.6 :1
F3 1930s aftermarket head
Model B, 3 bolt water pump provisions
Inch 7/8-18 spark plugs, over intake valves
Marked with "F3" and "Made in USA" on top

Copy of standard production Model B Ford combustion chamber
Heart 210-216 4.6 :1
M-6050 Ford GAZ (ГАЗ) Russia
1936-43 Standard Production head
Models ГАЗ-AA, ГАЗ-M1, & ГАЗ-67
Model B style, 3 bolt water pump provisions
Metric 18mm spark plugs, over intake valves
Marked with a large "C" on top, and "M-6050"
Heart 210-216 4.6 :1
M-ZM-6050 (?) Ford GAZ (ГАЗ) Russia
1944-53 Standard High Compression head
Model ГАЗ-67B
Model B style, 3 bolt water pump provisions
Metric ?mm spark plugs, over intake valves
? ? ? :1
BG-6050-B Ford Köln Germany
1930s Wood Gas Generator head (Imbert)
Model B, 3 bolt water pump
Inch 7/8-18 (or metric 18mm?) spark plugs
Marked "BG-6050-B" on top
For use with poured babbitt bearings
(mit ausgegossenen Lagern)
? 123-125 7.0 :1
G98T-6050 Ford Köln Germany
1939-42 Standard Production head
Model B style, 3 bolt water pump provisions
Metric 14mm spark plugs
Marked "G98T-6050" on top
same as B-6050 except for spark plug size
Heart 210-216 4.6 :1
G28TG-6050 Ford Köln Germany
1942 Wood Gas Generator head (Imbert)
Model B style, 3 bolt water pump provisions
Metric 14mm spark plugs
Marked "G28TG-6050" on top
For use with shell bearings (mit Lagerschalen)
? 94-96 8.5 :1
G38T-6050 Ford Köln Germany
1943-58 Standard Production head
Model B style, 3 bolt water pump provisions
Metric 14mm spark plugs
Marked "G38T-6050" on top
What is difference to "G98T-6050" ?
Heart 210-216 4.6 :1
BF-6050 Ford Dagenham England, 14.9 HP (R.A.C.)
1932-36 Standard Production 3 inch bore head
Model B, 3 bolt water pump
Inch 7/8-18 spark plugs
This head was produced by Ford England
for the 2.2L 14.9 HP (R.A.C.) Model BF engine
Only fits the Model BF engine block, no others
Mouse
Ears
100 psi 5.2 :1
Photo courtesy of Craig Lewis

Five different compression ratio cylinder heads were made for the Model A and B standard bore engine by Ford Motor Company themselves.

The following graph is derived by plotting the Ford-published data of the combustion chamber volume on the part drawing against the Ford-published data of the compression ratio of each head.

The compression ratio of an unknown flat head can be closely estimated by measuring the combustion chamber volume and reading the CR off the graph above.

The estimation would approximate the compression ratio that Ford would have claimed for that head using their measurement methods and calculations on a standard bore engine.


Photo courtesy of Marco Tahtaras

Thanks to Marco Tahtaras for allowing the use of his photo and method of measuring combustion chamber cc's here on Ford Garage!


More related information on Ford Garage:

  1. For more Model A & B related information, use the Site Search box at the top or bottom of this page.
  2. Model A & B Cylinder Head Comparison
  3. Model A Simmons High Compression Cylinder Head
  4. Model B Russian GAZ Cylinder Head  
  5. Model A Brumfield Cylinder Head and Gaskets
  6. Model A & B Model C Myth and Terminology
  7. Model A & B Cylinder Head Gasket Guide comprehensive listing
  8. Model A & B Cylinder Head Nut Tightening Sequence
  9. Model A & B Snap-on Cylinder Head Nut Wrench proper torque application tool
  10. Model A & B Cylinder Head Flatness Requirements by Larry Brumfield
  11. Model A & B Cylinder Head Gasket Installation Instructions by Larry Brumfield
  12. Model A & B Cylinder Head and Distributor Pullers by Ron Cloat
  13. Model A & B Broken Cylinder Head Stud and Bolt Removal
  14. Model A & B Cylinder Head Stud Removal Tools

April 2013