Size of starter fuseable link?

[FastWoman]

"For people replacing links with maxi-fuses, are you still comfortable with the fuse ratings given what I have managed to dig up?"

Everything is still working great! The fuse ratings I've used work fine. However, be warned that my alternator line is upgraded to 8 ga wire, so it can actually carry the amperage I've fused it for.

I'll also mention that the Stinger fuse blocks are working fine, even as they get rained on through the hood vent. I put a strip of clear packing tape over the top one to shield the water, and that works fine. Without the tape, the gold-plated steel screw plugs would rust.

Cozye, I decided to make the conversion because my fusible link assemblies were falling apart (both cover, base, and wire), and I could find no suitable replacements. I also feel, in hind-sight, that the maxifuses are much more solid, electrically. I admit I get a little smile on my face whenever I switch on my headlights and see that beautiful, bright, white light effortlessly coming out of the front of my car. It's the result of three upgrades -- alternator wire, maxifuses, and headlight relays.

Mike, even my '78 280 w/ 60A stock-configuration had a severely overstressed charge circuit, with a couple of black, melty areas to show for it.

[Mikes Z car]

I was hoping to avoid putting in another wire for the Alt to battery circuit but logic dictates otherwise, thanks FastWoman.

[FastWoman]

Sure thing, Mike. Don't worry, though. It's a pretty easy job. Just unwrap the wiring harness, pull out the scary, crimped, white and white/red wires, and make the requisite improvements. (I don't know how the 240s are wired.) For my alternator wire I used thin-insulated, teflon ensheathed 8 gauge like would be used in 220V household wiring -- sold by the foot at Lowes. I made my own alternator post connector out of a piece of copper tubing that I crimped around the wire (pinching one side of the tube) and soldered. The lug was made by flattening the other side of the copper tube in a vice and drilling a hole. I made other heavy connections by crimping inside small lengths of copper tubing, soldering, and wrapping with tape. I think I bought the Stinger maxifuse block off of Ebay. The bare end of the alternator wire clamps directly into the fuse block, and the block is fed by a 6 ga cable from the starter post. When you're done, just break out a roll of electrical tape, and wrap it all back up. It's probably a 1-2 hr job from start to finish, once you've assembled the parts, but if you're like me, you'll also do the headlight relays once you're into it.

[Mikes Z car]

Thanks FastWoman,

Appreciate the details on making the large alternator connector and on rewrapping the wire harness, I wondered what might be used. Sure would like to keep my ammeter working as for some reason it appeals to me as a means of knowing what is going on. Would have to run heavy gauge to and from it to the starter post.... Not sure that extra run is worth the trouble. Some use voltmeter readouts to avoid that. Ammeters use a shunt or near short circuit across them, I assume the shunt for the 240Z would be right across the ammeter connectors, does anyone know? Rambling a bit here.

I want to do the turn signal/brake relay mod but radio shack doesn't sell the cat no 702012 triple pole relay any more but I found them at Digi key:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1049447&k=702012

Mike

[FastWoman]

Mike, if you want your ammeter to read correctly (assuming it has numbers on its scale), you'll need to keep the same shunt. The gauge of wiring that runs to it and/or the type of alternator on the other end is irrelevant, as far as the operation of the gauge is concerned.

I don't know many/most details of the wiring of your 240, but I would think you could consider this alternative approach that might be a bit easier to retrofit:

(1) Identify the wires that run between the ammeter and the engine compartment.

(2) Move the shunt from the back of the ammeter to the engine compartment, connecting it between the outgoing and returning wire.

(3) Run your heavy wiring everywhere else (from the alternator to the shunt, from the other side fo the shunt to the fusible link, from the other side of the fusible link to the battery)

The heavy OEM wires running from the shunt to the ammeter will then carry very low current and will be overkill, but at least you won't have to strip them out of the wiring harness running under/behind the dash.

If you want the full scale of the ammeter to reflect more amps (e.g. 60A, rather than 40A), find a lower resistance shunt for it. You can make your own shunt out of a strip of iron/steel. To change from a 40A to 60A full scale reading, you'll need a resistance that's 2/3 the value of what you already have. Alternatively, you could keep the shunt you have, and insert another shunt in parallel (bolted to the same terminals) of twice the resistance value. You'll need a really sensitive and accurate meter to measure these low resistances. Either that, or you'll need to measure the resistance of a very long piece of the material you're going to use, and then you can calculate the ohms per cm to determine the length of shunt you'll need.

Regarding the turn signals and brakes: Why not just go to electronic flashers and LED lights? That's what I'm going to do. The only problem is that my local auto parts store just sold out its entire stock of LED replacement "bulbs" because nobody would buy them, and I missed the chance to scoop them up out of the 75% off clearance bin. Grrrrr...

Edited December 1, 2010 by FastWoman

[Mikes Z car]

FastWoman,

That is a terrific idea of moving the shunt. It might be okay with the same shunt if I remember that in a worst case scenario with a dead battery it might peg showing over 40A for a while until it charges a little at least I assume that is worst case. Capturing all loads through the ammeter would mean I would have to relocate the power wire for the parking light relay mod to the starter post. I will have to ponder on doing that.

Not sure I want to go with LEDs at least yet anyway.

Mike

[MrDanno]

Can I ask a basic quesiton I believe my fusible link on my 73 needs replaced due to a battery short, but I can't figure out exactly which wire it is. Every wiring diagram I see has the link coming right off of the starter, but when looking at it, I only see a few wires- the ignition relay which slides onto the solenoid, positive cable, a wire coming off of the starter into the solenoid. Any visual help would be much appreciated!

thanks