A Guide to the 1958-1959 GMC F370 Distributor Cap
Keep your classic GMC's ignition system firing reliably with the right new distributor cap.
- A bad distributor cap will cause misfires, rough idle, hard starting, and potential stalling.
- Always replace the distributor rotor at the same time as the cap for a complete repair.
- Aftermarket brands like Standard Ignition and Walker Products are the primary options for new parts.
- To avoid firing order problems, transfer spark plug wires from the old cap to the new one, one at a time.
Is Your Distributor Cap Failing?
The distributor cap and rotor are wear-and-tear items. Over time, the plastic or bakelite material can develop tiny cracks from heat and age. The metal terminals inside can corrode or get coated with carbon deposits. When this happens, the electrical spark can weaken, arc to the wrong place, or fail to reach the spark plug wire. This causes noticeable engine problems. A visual inspection is often the best way to diagnose a bad cap. Look for cracks, moisture, white crusty corrosion, or black carbon dust on the terminals inside.
Aftermarket Distributor Caps for Your F370
For a vintage truck like the 1958-1959 F370, new original equipment (OEM) parts are generally unavailable. The aftermarket is the primary source for new ignition components. Fortunately, reputable brands produce high-quality replacements that meet or exceed the original specifications.
| Brand Tier | Brand(s) | General Assessment |
|---|---|---|
| Premium Aftermarket | Standard Ignition (SMP) | Standard Motor Products is a long-standing leader in ignition parts, often considered a top-tier choice by professional mechanics. They are known for using high-quality materials like glass-reinforced polyester resin for the cap and solid brass for the terminals, which provides excellent resistance to heat, carbon tracking, and corrosion. |
| Quality Aftermarket | Walker Products | Walker Products is another established brand that manufactures reliable replacement parts. They engineer their caps to meet OE specifications for fit and function, using high-dielectric materials to ensure proper insulation and performance. For a stock truck, a Walker cap is a dependable and cost-effective option. |
Confirm Your Engine
In 1958 and 1959, GMC used a 336 cubic inch V8 engine in some of its trucks. However, different engine options, including inline-six engines, were also available. Always confirm your specific engine before ordering to ensure you get the correct cap.
Frequently Asked Questions (FAQ)
Should I replace the distributor rotor with the cap?
Yes, absolutely. The rotor is the spinning part inside the cap that distributes the spark. It wears out at the same rate as the cap. Replacing them together is a standard part of a tune-up and ensures the entire ignition system is refreshed.
How difficult is it to replace the distributor cap?
This is one of the easiest jobs you can do on your truck. The cap is typically held on by two clips or screws and is located right on top of the engine. The only tool you might need is a screwdriver. The entire job usually takes less than 30 minutes.
What is the most common mistake when replacing a distributor cap?
Mixing up the spark plug wires. This will cause the engine to run terribly or not at all. To avoid this, transfer the wires from the old cap to the new cap one at a time. You can also label each wire with masking tape and a number corresponding to its position on the cap before you begin.
Are there any recalls for the distributor cap on a 1958-1959 GMC F370?
No. There are no recalls or Technical Service Bulletins (TSBs) on file with the National Highway Traffic Safety Administration (NHTSA) for this part on this vehicle. Recalls for vehicles this old are extremely rare and NHTSA's public database does not typically contain information for recalls older than 15 years unless a manufacturer offers special coverage.
Technical Specifications
The 1958-1959 GMC F370 was available with different engines, including a V8 and various inline-six options. It is critical to verify your truck's specific engine to ensure you purchase the correct distributor cap, as the V8 and 6-cylinder caps are different.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.