Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

1966 GMC 2500 Automatic TransFACTORY OEM SERVICE PROCEDURE

Ford Motor Co. LOADOMATIC Distributor Advance Specifications

NOTE: FOR ENGINE RPM AND DEGREES, MULTIPLY SPECIFICATIONS BELOW BY 2.

Distributor Part No. ⁽¹⁾

Rot. ⁽²⁾

Distributor Advance Specifications

Max. Adv.

Deg.

Vac.

RPM

Deg.

Vac.

RPM

Deg.

Vac.

RPM

Deg.

Vac.

RPM

C5DF-C

2 1/2-3 1/2

0.8

800

6 1/2-7 1/2

1.8

1200

8 3/4-10

3.0

1800

10 1/4-11 1/2

3.9

2000

14 1/2°

C5DF-E

1-2

0.44

600

5-6

1.8

800

8 1/4-9 1/4

1.9

1200

10 1/4-11 1/2

3.8

2000

15 1/2°

C5DF-K

3/4-1 3/4

.79

800

3 3/4-4 3/4

1.9

1200

5 3/4-7

3.0

1600

7-8 1/4

3.8

2000

12 3/4°

C6TF-AC

4 1/2-5 1/2

1.2

800

7 1/2-8 3/4

2.1

1200

9 1/4-10 1/2

3.7

1600

10 1/4-11 3/4

4.9

2000

14°

C6AF-Y

1-2

.90

800

4 1/2-5 1/2

2.1

1200

7-8 1/4

3.6

1600

8 3/4-10

4.8

2000

12 3/4°

⁽¹⁾	Stamped on housing or on attached plate. Basic Ford Part No. is "12127".

⁽²⁾	C - Clockwise; CC - Counterclockwise (viewed from rotor end).

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.

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