Amp gauge/alternator modification

[texas69bee]

I am sure some of you have seen this modification http://www.madelectrical.com/electricaltech/amp-gauges2.shtml. My current alternator is rated at 90amps, I believe I need a 10 gauge wire going from the alternator to the starter relay. What size fusible link would I need?
The wires going into the bulk head are currently 12 gauge, am I right in thinking these will be fine because they no longer receive full amperage, just what is needed?

 

[Budnicks]

100 amp maybe pushing it with 12 ga. wire thou

I've done sort of that mod to a few of my cars;
But a 75amp. alt. & I used a 8 ga. wire
going from the main output 1/4-20 stud on the back of the alt.,
back to the starter relay 1/4-20 large lug, helps to shorten the path/less load,
all the rest of the OE wires are still there, still intact too...
It helps to lessen the load from the alt. & wiring, especially under-dash & amp ga....
But I still have the amp ga. inline, haven't removed it yet, it works great...

I have a rear trunk mounted Battery too, made a world of difference...

Make absolutely sure you have really good & properly sized grounds/straps too,
battery to chassis/body
& engine to chassis/body,
always make sure no paint between the connections,
I use star washers & dielectric grease always too...

I recommend people to go to Mad Enterprises site go thru the list below
@ http://www.MadElectrical.com/electrical-tech.shtml
Dodge amp. ga. stuff is near the bottom of the page, good/must read,
also use them all the time for various electrical tech stuff & supplies...

I actually replaced the fusible link with a resettable 10-15 amp breaker
{20 amp breaker on my current wiring, but it's a custom harness now too}...

My cars wiring was hacked by the previous original owner...

Still needs some stuff I'll get to when I install my new custom gauge panel...

I have it on my current 68 RR too,
make certain no bad/loose wires or connections to the amp ga.
& make sure all amp ga. connections are clean/tight,
the large black wire that feeds all the electrical under the dash,
thru the amp ga. in thru the firewall bulkhead connection,
& make sure all the bulkhead connections are clean too,
make sure to use dielectric grease on all connections too...

done it to a few cars now no issues yet, even had a volt meters/ga. inline too

everything goes thru the big black amp ga. wiring underdash,
I couldn't be more serious, to make absolutely sure !!
it's all really good connections & covered properly, I solder & shrink wrap...

it can start a serious fire, it's no joke

Sorry I didn't do that exact mod, they show, but it's easy too...
But if you have any real questions just contact them,
they will/should usually help you, probably recommend a part/piece they can sell you too...

 

[65-440]

Done a few of these wiring upgrades also, if I remember correctly Mark recommends a fusable link 2ga difference than the circuit it will be protecting ( 10ga wire needs 14ga link, etc .... )

 

[hunt2elk]

I did the MAD bypass on one of my cars. I used a 60 amp alt which needed a 10 gauge wire from it to the starter relay. With a 75 amp alt, the charts show you should use a 8 gauge wire, with a 12 gauge fusible link.

 

[eric383]

I also highly recommend installing a relay for the headlights. That way you aren't pulling as many amps through the headlight switch.

 

[texas69bee]

I did manage to get a hold of Mark Hamilton, the owner/creator of MADELELECTRICAL. Great guy, very knowledgeable but you better have some time on your hands cause he likes to talk and teach.

 

[twinscrew698]

Question for you that made the upgrade.
Can you use a heavier gauge wire until you upgrade the Alt?
Like i have a Std i think 37 amp Alt,can i upgrade the current wire to 8-10 gauge and leave my std Alt on til i change to a Higher Amp Alt?
And if i need to Change Alt,which style brand is recommended for a stock look?

 

[Budnicks]

Yes
you could use the heavier ga. wire, prior to the higher amperage Alt. conversion...

Ii sounds like you are doing more of a restoration/alteration

BUT;
I modify most all my cars & used a dual field alt, 4pin ballast & an appr. M&H harness from Year One
{I also used a CEI electronic ignition too & electronic regulator from 1973 @ latter,
it's far better system than the 68-69
I used a Chrome case 75 amp Powermaster or MSD 100 amp Alt.'s,
the OE style look {Chrysler built their own}
68 OE 37amp. had a Chry. case/part# 2642537
for 69 OE 37amp. had a Chry. case/part# 2642944
& which brand question, of repop's, somebody else may give a better answer...

good luck either way

 

[twinscrew698]

Ok Thanks Budnick
Also to use an 8 Gauge wire we should use for a Fusible link 12 Gauge or use what size Circuit Breaker?

 

[moparjohnny]

where do buy relays for the headlights and the heat sink rap that goes on wires. thanks

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I also highly recommend installing a relay for the headlights. That way you aren't pulling as many amps through the headlight switch.

where to you buy relays for headlights?

 

[twinscrew698]

where do buy relays for the headlights and the heat sink rap that goes on wires. thanks

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where to you buy relays for headlights?

Try here!
http://madelectrical.com/catalog/rly-1.shtml

 

[moparjohnny]

read the mad by pass article understand everything but if you by pass the factory ammeter what do you do for a ammeter?says nothing about adding a volt meter can someone clarify please. thanks

 

[snakeoil24]

Trust mark from mad Electric!

 

[moparjohnny]

what would be wrong if you added a fuse link from the alternator line and a fuse link from the battery line that goes to the ammeter,wouldn t that protect the system from a fire hazard? just asking i do not know.

 

[texas69bee]

Moparjonny, I don't believe it will work the way you think. The amp meter is receiving a full load already and that it what is causing the melt downs. The fuse would work for a surge. Any questions you may have, Mark will have the answer. If you want parts from Madelectrical, you have to call him anyway.

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twinscrew698... Mark will tell you that at 90amps you can get by with a 10 gauge wire if you are not using a clutch fan. If you have to red wires coming from your battery, he will tell you to put in a fusible link(14 gauge) to the one that goes to the starter relay. From the ammeter you will still use a 16 gauge fusible link. When doing his modification you can use a 10 gauge through the bulk head as well. The current is being shared by 2 wires. I went with the powermaster round back 2field alternator as budnicks suggested. Minimum rating is now 90amps per there website. The upgrade wire harness I used is M&H from yearone.com. It is set up for a 4 pin ballast resistor but the ecu boxes coming out now are a 4pin that uses a 2 pin resistor. The other resistor is now internal.

 

[twinscrew698]

Texasbee.Thanks for your input, now i have a very good idea of what i am going to do.