Fusible Links Article

[Edward B.]

The presentation on fusible links by the late Dick Robinson that appears in the latest issue of The Corvette Restorer (Summer, 2021, pp. 36-37) is one of the best technical explanations that I have ever had the pleasure to read. Concise and focused, it summarizes the function of these important parts, their failure modes and their repair procedures. I suggest that our members pay tribute to Mr. Robinson's memory by reading and understanding the information set forth therein about these often overlooked parts.

[Daniel S.]

Re: Fusible Links Article

I was reading it last night too... Not only is the technical info good, but the photos presented (of our former '67 L36 5-Star Bowtie car) are outstanding too.

Dan

[Mark E.]

Re: Fusible Links Article

Are there any issues with replacing a fusible link with a Maxi fuse (other than not looking original)? I like the idea of easy repair on the road for a driver car.

How should the fuse be sized compared to the fusible link it replaces?

[Richard M.]

Re: Fusible Links Article

Mark, Difficult to answer. To properly size a fused circuit, one needs to know the max current the circuit will draw, wire gauge size, then size the fuse at a slightly higher value.

E.G. On the C1's, I use a 30A fuse at the Ammeter input. This is to cover a catastrophic short upstream from the engine harness. I had a VR short out at the Bat & Gnd once. Saved the day. A dummy dropped a screwdriver and it landed across the exposed screws, poof went the fuse fortunately. It would have fried the harness because I couldn't reach down fast enough to retrieve it as the fresh air hose blocked me out. BTW, dummy was me!

IGN, Lighter and Clock, 15A each. (IGN optional. GM never put a FL or fuse on that. Likely to avoid a possible additional "engine-dead-while-underway" fault potential. (But ok to burn up the car if a short happened!)

Rich
PS The 30A fuse at the Ammeter saved the '57 Super Sport when John Baldwin and I were trying to get it running for the first time after sitting 20 years. The original chrome covered VR was shorted internally. We were happy the fuse was there.

[Terry M.]

Re: Fusible Links Article

Are there any issues with replacing a fusible link with a Maxi fuse (other than not looking original)? I like the idea of easy repair on the road for a driver car.

How should the fuse be sized compared to the fusible link it replaces?

The fuses/circuit breakers in your home and shop should be sized for the wire size of the circuit. The actual load placed on the circuit does not influence the fuse/breaker size. The thought is to prevent the wire burning up. I can't imagine why an automotive circuit would be any different.

You should be aware that some fuses are designed to blow (operate) with a delay. I would avoid those fuses on an automotive circuit. More than you ever wanted to know about automotive fuses:

https://www.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/blade-fuses/littelfuse_atof_datasheet.pdf

A little Google search will reveal more if this isn't enough

[Mark F.]

Re: Fusible Links Article

....More than you ever wanted to know about automotive fuses:
https://www.littelfuse.com/~/media/a..._datasheet.pdf A little Google search will reveal more if this isn't enough...

http://www.offroaders.com/technical/12-volt-wiring-tech-gauge-to-amps/

[Jim L.]

Re: Fusible Links Article

You should be aware that some fuses are designed to blow (operate) with a delay. I would avoid those fuses on an automotive circuit.

The fast acting fuse protecting the tail light circuit of my '63 would not withstand the start-up current of four, cold filaments. I replaced it with a Slo Blo fuse and it's been OK ever since.

My dim memory is that the shop manual actually specifies a Slo Blo fuse for that circuit.

[Richard M.]

Re: Fusible Links Article

Good info.

Jim, I once worked on a early 63. Somebody wrapped the TL fuse in aluminum foil. Must've been in a TSB. lol.

[Mark E.]

Re: Fusible Links Article

The fast acting fuse protecting the tail light circuit of my '63 would not withstand the start-up current of four, cold filaments. I replaced it with a Slo Blo fuse and it's been OK ever since.

My dim memory is that the shop manual actually specifies a Slo Blo fuse for that circuit.

The limited research I've done also said the best fuse type to use for replacing a fusible link is a "slo blo" as you say... It looks like one type is called a Maxi fuse. Apparently fusible links are designed to not blow from a brief voltage or current spike, unlike most fuses.

Richard- Thanks so much for the insights.

Mark and Terry- Thanks for the references. I'll give them a look.

[Jim L.]

Re: Fusible Links Article

The limited research I've done also said the best fuse type to use for replacing a fusible link is a "slo blo" as you say....

FYI: Slo Blo is not something I just made up. It is a trade name for a type of fuse which will endure brief over-current situations, such as what happens when Voltage is first applied to a cold lamp filament.