Flathead Engines
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 This section is all about the wonderful Ford Flathead. Truly an engine before it's time.... don't believe me? Check out all the new parts still being made for the Ford Flathead because of the awesome indesctructible construction of the cast iron block. These are truly an amazing part of American history. Anyway, on to the good stuff. From time to time I will be adding more information to this page as it is added to the site. If you have any suggestions, please contact me. Thanks!
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Paint Colors
Here is a list of the paint colors of Flathead Engines:
|
Year
|
Ford
|
Mercury
|
Truck
|
Commercial
|
|
1932
|
Dark Green |
N/A |
Dark Green |
Dark Green |
|
1933
|
Dark Green |
N/A |
Dark Green |
Dark Green |
|
1934
|
Dark Green |
N/A |
Dark Green |
Dark Green |
|
1935
|
Dark Green |
N/A |
Dark Green |
Dark Green |
|
1936
|
Dark Green |
N/A |
Dark Green |
Dark Green |
|
1937
|
Dark Green |
N/A |
Dark Green |
Dark Green |
|
1938
|
Dark Green |
N/A |
Dark Green |
Dark Green |
|
1939
|
Dark Green |
Dark Green |
Dark Green |
Dark Green |
|
1940
|
Dark Green |
Dark Green |
Dark Green |
Dark Green |
|
1941
|
Dark Green or Dark Blue |
Dark Blue |
Dark Green |
Dark Blue |
|
1942
|
Dark Green |
Dark Blue |
Dark Green or Dark Blue |
Dark Blue |
|
1943
|
Unknown |
Unknown |
Unknown |
Unknown |
|
1944
|
Unknown |
Unknown |
Unknown |
Unknown |
|
1945
|
Unknown |
Unknown |
Unknown |
Unknown |
|
1946
|
Dark Blue |
Dark Blue |
Dark Blue |
Dark Blue |
|
1947
|
Dark Blue |
Dark Blue |
Dark Blue |
Dark Blue |
|
1948
|
Dark Blue |
Dark Blue |
Dark Blue |
Deep Red |
|
1949
|
Dark Blue |
Green |
Dark Blue or Green |
Deep Red |
|
1949 1/2
|
Bronze |
Green |
Bronze or Green |
Deep Red |
|
1950
|
Bronze |
Green |
Bronze or Green |
Deep Red |
|
1951
|
Bronze |
Green |
Bronze or Green |
Deep Red |
|
1952
|
Tangerine or Green |
Tangerine or Green |
Green |
Green |
|
1953
|
Tangerine or Green |
Tangerine or Green |
Green |
Green |
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Flathead Horsepower Curve
 A 89HP at 3600RPM - Stock 100HP Ford flathead V8 (corrected)
B 114HP at 3800RPM - Same engine with dual intake manifold.
C 124HP at 4000RPM - Same as B with 8.5:1 compression heads.
D 140HP at 4400RPM - Same as C with 3/4 race camshaft.
E 145HP at 4500RPM - Same as D with special exhausts.
F 177HP at 4500RPM - Same as B, bored 1/8 inch, stroked 1/8 inch, ported, relieved, 9:1 heads.
G 197HP at 4700RPM - Same as E but with super track cam and methanol fuel.
Back to Flathead Engines
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Flathead Engine Specifications
|
Year
|
Model
|
CID
|
Bore
|
Stroke
|
Compression |
HP@RPM |
Head Studs |
Main Journal |
Rod Journal |
|
1932
|
18
|
221
|
3-1/16
|
3-3/4
|
5.5:1
|
65@3400
|
21
|
1.998-1.999
|
1.998-1.999
|
|
1933
|
40
|
221
|
3-1/16
|
3-3/4
|
6.33:1
|
75@3800
|
21
|
1.998-1.999
|
1.998-1.999
|
|
1934
|
40A
|
221
|
3-1/16
|
3-3/4
|
6.33:1
|
85@3800
|
21
|
1.998-1.999
|
1.998-1.999
|
|
1935
|
48
|
221
|
3-1/16
|
3-3/4
|
6.33:1
|
85@3800
|
21
|
1.998-1.999
|
1.998-1.999
|
|
1936
|
68
|
221
|
3-1/16
|
3-3/4
|
6.33:1
|
85@3800
|
21
|
1.998-1.999
|
1.998-1.999
|
|
1937
|
78
|
221
|
3-1/16
|
3-3/4
|
*
|
**
|
21
|
2.398-2.399
|
1.998-1.999
|
|
1938
|
81A
|
221
|
3-1/16
|
3-3/4
|
6.12:1
|
85@3800
|
21
|
2.398-2.399
|
1.998-1.999
|
|
1939
|
91A
|
221
|
3-1/16
|
3-3/4
|
6.15:1
|
85@3800
|
24
|
2.498-2.499
|
1.998-1.999
|
|
Merc
|
99A
|
239.4
|
3-3/16
|
3-3/4
|
6.3:1
|
95@3600
|
24
|
2.498-2.499
|
1.998-1.999
|
|
1940
|
01A
|
239.4
|
3-3/16
|
3-3/4
|
6.3:1
|
95@3600
|
24
|
2.498-2.499
|
1.998-1.999
|
|
Merc
|
09A
|
239.4
|
3-3/16
|
3-3/4
|
6.3:1
|
95@3600
|
24
|
2.498-2.499
|
1.998-1.999
|
|
1941
|
11A
|
239.4
|
3-3/16
|
3-3/4
|
6.3:1
|
95@3600
|
24
|
2.498-2.499
|
1.998-1.999
|
|
Merc
|
19A
|
239.4
|
3-3/16
|
3-3/4
|
6.3:1
|
95@3600
|
24
|
2.498-2.499
|
1.998-1.999
|
|
1942
|
21A
|
239.4
|
3-3/16
|
3-3/4
|
6.2:1
|
90@3800
|
24
|
2.498-2.499
|
1.998-1.999
|
|
Merc
|
29A
|
239.4
|
3-3/16
|
3-3/4
|
6.4:1
|
100@3800
|
24
|
2.498-2.499
|
1.998-1.999
|
|
1943
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
|
1944
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
|
1945
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
|
1946
|
69A
|
239.4
|
3-3/16
|
3-3/4
|
6.75:1
|
100@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
|
Merc
|
59A
|
239.4
|
3-3/16
|
3-3/4
|
6.8:1
|
100@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
|
1947
|
79A
|
239.4
|
3-3/16
|
3-3/4
|
6.8:1
|
100@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
|
Merc
|
59A
|
239.4
|
3-3/16
|
3-3/4
|
6.8:1
|
100@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
|
1948
|
89A
|
239.4
|
3-3/16
|
3-3/4
|
6.8:1
|
100@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
|
Merc
|
59A
|
239.4
|
3-3/16
|
3-3/4
|
6.8:1
|
100@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
|
1949
|
98BA
|
239.4
|
3-3/16
|
3-3/4
|
6.8:1
|
100@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
|
Merc
|
CM
|
255.4
|
3-3/16
|
4
|
6.8:1
|
112@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
|
1950-1953
|
8BA
|
255.4
|
3-3/16
|
4
|
6.8:1
|
112@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
|
Merc
|
CM
|
255.4
|
3-3/16
|
4
|
6.8:1
|
112@3800
|
24
|
2.498-2.499
|
2.138-2.139
|
"---" = Not
produced due to WWII.
"####" = Ford
"Merc" = Mercury (year ####)
"*" = w/ aluminum heads -
6.2:1
"*" = w/cast iron heads -
7.5:1
"**" = w/ aluminum heads
- 85@3800
"**" = w/cast iron heads
- 94@3800
Back to Flathead Engines
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Modified Flathead Cubic Inch Displacement (CID) Chart
CID of a modified Flathead
Bore in Inches
Stroke in Inches
|
3-3/4"
|
4"
|
4-1/8"
|
|
3-1/16"
|
220
|
236
|
243
|
|
3-3/16"
|
239
|
255
|
263
|
|
3-5/16"
|
258
|
274
|
284
|
|
3-5/16" (+ .030 over)
|
263
|
281
|
289
|
|
3-3/8"
|
268
|
286
|
296
|
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Ford Manufactured Head Specs
| Part #'s |
Mat. |
Comp
Ratio |
Max HP |
Max Torque |
Comp. Pressure |
# Studs |
Piston Type |
Volume |
| RH |
LH |
HP |
RPM |
Lbs |
RPM |
Lbs |
RPM |
C-Lbs |
| 81A-6049A |
81A-6050A |
Iron |
6.6:1 |
95 |
3800 |
170 |
2000 |
150 |
2200 |
116 |
24 |
Dome |
78-80cc |
| 81A-6049A |
81A-6050A |
Alum |
6.6:1 |
95 |
3800 |
170 |
2000 |
145 |
2000 |
116 |
24 |
Dome |
78-80cc |
| 81T-6049 |
81T-6050 |
Iron |
6.3:1 |
95 |
3800 |
170 |
2000 |
145 |
2200 |
112 |
24 |
Dome |
83-85cc |
| 81AS-6049 |
81AS-6050 |
Iron |
8.0:1 |
100 |
3800 |
175 |
2000 |
165 |
2200 |
132 |
24 |
Dome |
60-62cc |
| C91A-6049B2 |
C91A-6050B2 |
Alum |
6.9:1 |
100 |
3540 |
185 |
1850 |
165 |
2000 |
105 |
24 |
Dome |
74.5-76cc |
| C99A-6049B1 |
C99A-6050B1 |
Alum |
6.9:1 |
100 |
3540 |
185 |
1850 |
165 |
2000 |
105 |
24 |
Dome |
74.5-77cc |
| C99A-6049B2 |
C99A-6050B2 |
Alum |
6.5:1 |
95 |
3600 |
180 |
1850 |
155 |
2000 |
100 |
24 |
Dome |
81.0-82.5cc |
| 99AS-6049 |
99AS-6050 |
Iron |
7.6:1 |
100 |
3800 |
175 |
2000 |
160 |
2300 |
132 |
24 |
Dome |
65-67cc |
| 99T-6049 |
99T-6050 |
Iron |
5.9:1 |
95 |
3600 |
170 |
2000 |
140 |
2200 |
106 |
24 |
Dome |
90-92cc |
| 19AS-6049 |
19AS-6050 |
Iron |
7.1:1 |
98 |
3800 |
172 |
2000 |
163 |
2300 |
124 |
24 |
Dome |
70-72cc |
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|
Flathead Spark Plugs
Not a whole lot I can tell you here. Running hot plugs in an engine too long at high RPMs can burn pistons and valves. It can also add to overheating problems. On the other hand, running cold plugs can leave unburned fuel in the cylinders which can break down lubricant, etc. It's a game of cat-and-mouse so good luck. Here are some which work on 12V electronic ignition systems.
| Hot: |
Cold: |
RJ 20 YC
RJ 18 YC
RJ 14 YC
RJ 13 YC
RJ 12 YC
RJ 11 YC
|
RJ 10 YC
|
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Flathead Compression Ratios
Ok, here we go... This is a chart of basic compression ratios on a stock motor, this is not
guaranteed to be correct. If you want accuracy talk to a local motor shop, they'll be able to
give you a really good idea. =)
| Lbs in Cylinder: |
Basic Comp Ratio: |
120
130
140
150
160 |
6.5 to 7.5
7.5 to 8.5
8.5 to 9.5
9.5 to 10.5
10.5 to 11+ |
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Flathead Lifter Adjustment Order
Here's the proper order for adjusting the lifters which also helps to center the camshaft:
3
7
12
16
14
10
6
2 |
1
5
9
13
15
11
8
4 |
|
<|||||||||||||>--\_/--<|||||||||||||>
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Back to Flathead Engines
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Flathead Torque Specifications
Torque Specs : 1949-1953 Flathead V-8
Main Bearing Bolts : 95-105
Cylinder Head Bolts : 65-70
Oil Pan to Cylinder Block : 15-18
Oil Pan to Rear Engine Plate : 10-15
Flywheel Bolts : 75-85
Exhaust Manifold : 25-30
Intake Manifold : 23-28
Cylinder Front Cover : 12-15
Water Pump : 23-28
Water Outlet Elbow : 12-15
Fuel Pump : 6-9
Generator Bracket : 55-70
Camshaft Gear : 15-20
Clutch Pressure Plate Assembly : 17-20
Connecting Rod Nuts : 45-50
Connecting Rod Lock Nuts : 4-5
Starter to Engine : 15-20
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