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Completed my installation of a fuse block to replace the ageing fusible links.

Used the same Mini ANL block that Mike W used in his 260, except purchased the 4 fused output block. One 80A ANL for the alternator feed back, and three 50A for the other circuits were the fuses I used.

This model has 2 inputs so I will eventually run another cable from the unused port to a inexpensive 2 output small fuse block without the digital bling for the FI links.

The display has 4 led's for the fuse status, and the system volts / current. The display cycles between volts & amps about every 10 seconds and shuts itself off in 90 seconds if there is no circuit activity. A good thing, I was worried it would stay lit up all the time & was getting ready to put a small toggle switch on the ground wire for the display to kill it. Worked out well.

Fairly accurate, shows my battery to be 12.9 volts when the car is off. Shows my parking / dash lights are 3 to 4 amps when on.

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  • 1 year later...

IMO, replacing the fusible  links with fuses is a very dangerous thing.   Who started all the fusible link- fuse equivalence stuff??

 

The fusible links are protecting some very important things that draw a lot of current, like the headlamps and the fuel injection system, and  you will have instantaneous trouble if the fuses melted.  Fusible links are like circuit breakers, so you would want to use those in stead. You can get circuit breakers that plug into fuse  clips.

Edited by TomoHawk
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As I understand it, the function is pretty much the same in a fusible link as it is in a Maxi Fuse. Current draw above the rated size of the link or the fuse causes the wire or fuse to melt and opens the circuit. Why would it act any different?

 

This article explains it fairly well...

 

http://www.autoshop101.com/forms/hweb1.pdf

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Maxi Fuses are bigger than the standard fuses, but still  aren't the same as fusible links.  Without re-engineering the wiring for fuses, you invite unpredictable results.

Edited by TomoHawk
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Maxi Fuses are just more robust fuses, but still  aren't the same as fusible links.  Without re-engineering the wiring for fuses, you invite unpredictable results.

 

I don't disagree in theory, however, I am of the opinion that fusible links inherently invite more risk of failure than a Maxi Fuse. Fusible links are merely wire of a gauge 4x smaller than the rated current of the device it is protecting. In case of an overcurrent, the wire melts withing the heavy duty sheilding and protects the circuit. A Maxi Fuse does the same thing, only in a fuse style and in a design for high current draw circuits. If Maxi's had been available at the time, Datsun would probably have used them instead. At that time, fusible links were the traditional method of securing high amperage circuits for which fuses were not rated. 

IMHO Maxi Fuses are an elegant solution to an older technology. Maxi's provide a quick visual reference to the condition of the circuit as well. Fusible links are visually harder to identify as serviceable...

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They still use fusible link in modern cars.  My 1997 has all three kinds, regular blades, cartridges, and fusible links.  I would rather use the cartridge than a Maxi fuse,  They were designed to be more robust than regular fuses, like the fusible link.

 

It's true that  you'll need to diligently maintain the electrical system so fusible links can perform as they did when the car was new, but it easier than replacing the entire electrical system.

Edited by TomoHawk
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I have had a hard time finding a fuse block that will work with the cartridges. I agree they are more similar to the fusible links.

 

As I am doing the whole car anyways, one of my plans was to clean up the engine bay. Pallnet fuel rail, hidden injector wires, rerouted fuel lines, carbon canister, brake booster and vacuum lines etc. Adding the Maxi Fuses as a way to eliminate the fusible link connection is a real easy step and I will move them to the firewall along with the fuel pressure regulator and fuel filter.

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I'd like to see a write-up of how to route the fuel injector wires so they go along the firewall, then to the back of the intake manifold. 

 

When I get to doing mine, I will try and accomodate if it has not been done already. I plan on splitting the harness for just this purpose. Plus I am going to 11mm barbless injectors so I need to redo the wiring regardless.

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My thoughts? I honestly don't know. My questions are:

 

"Is there any functional difference in operation between fuses and fusible links?" and the follow-up question of

"When designing in a protection device, what would make you choose a fusible link over a fuse?"

 

I spent a little time looking into the above questions a while ago and about the only thing I could turn up on-line was that fusible links were historically used in applications where fuses were unavailable because of the current capacity.

 

So back in the mid seventies, forty and fifty amp fuses, especially in the glass tube style used in our fuse blocks simply weren't available. But if you look under the hood of cars now, you see cartridge fuses of 100A or even more coming right off the battery terminal. I guess the answer could be that parts like that just simply weren't available back when our cars were designed, and if they were designing them again today, everything would have been fuses instead of of fusible links.

 

However... In engineering, frequently even the seemingly mundane is often much more complicated than it appears to the non-expert. I wouldn't be surprised if an EE from Bussman would be rolling his eyes right now at my lack of understanding.

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Always nice to get a "Sparkys" input on such things.

 

Haha! My pleasure. Just remember that I gave a "non-answer" though!! Just anecdote and input from someone not trained in the fuse art. Wish I knew more and could have been more definitive.

 

Still awaiting SteveJ's wading into the fray. Maybe he's got the kung-fu.

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I'm going to guess that fusible links are just the slowest of the "slow-blow" fuses.  They all work on the same principle, amps cause heat, too many amps cause melting.  The only question is how fast do you want it to melt.

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Yup, the headlamp fusible wire (red) on my '78 looks like an 18 ga. wire, and it's got a potential 20A to go through it.  You wouldn't want it to 'pop' when you go to the high beams on a twisty country road, so you know those things are really tough stuff.

 

The same is for the fuel injection fuse links (but I can't think of why you need three.)  The (black) one for the cabin main & accessories supposedly handles 100A,  and it looks like a 14 ga wire.

Edited by TomoHawk
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Picked one of these up this morning. Looks like it should do the job just fine. I'll make sure to get the appropriate size ANL fuses too.

dbc62acb202626036935a6b18ca2a1fb.jpg

Sent from my iPizzle ringy dingy device....

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  • 2 weeks later...

Parts arrived today. Works pretty good and I have installed some test fuses that are the flat metal style. They should act the same as fusible link wire. Need to source more accurate fuse rating fuses.

Voltage indication is accurate (according to my digital power supply) and fuse integrity LEDs work good too.

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Voltage indication goes out in about 30 seconds of inactivity of current draw. LEDs stay on but draw near to zero amps.

6044b6a8073d64bbbd8a2f00ec01d143.jpg

Sent from my iPizzle ringy dingy device....

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