[mike pratola]

Hi all, been away for a bit but back on this project with a question. 69 Malibu power top convertible, factory A/C. The original 307/Powerglide has been swapped for a L98 350 w/ HEI,/700r4, and am in the process of changing the stock fuel gauge/idiot light cluster for an aftermarket replica SS tach/oil pressure/temp/fuel and amp cluster. I also plan on adding Holley sniper EFI with an in tank fuel pump I have after the new drivetrain is dialed in. In anticipation of adding the Sniper and its additional current requirements, I've installed a Tuff Stuff 100 amp externally regulated alternator and electronic voltage regulator. This was chosen over a one wire set up to keep the amp gauge function and the engine bay's original look. My dilemma is with the amp meter. I'm told it won't survive the extra amps, American Autowire's upgrade harness doesn't have a provision for it.
Looking at the meter, it doesn't look like the old traditional meters I'm used to that carry full current, the wires running to it from the harness look like 16-18 gauge, no way they would handle any type of load. So I'm wondering if this is a true amp gauge or some type of volt meter that reads as a quasi amp meter? As it only reads plus or minus and the small gauge wiring I'm thinking it should be OK to use with the higher output alternator. I'd also like to replace the under dash wiring harness with an OE type that would retain the amp meter function. Anyone else been down this road or have any experience with this? Thanks in advance.

 

[69SS454]

It is a paralleled volt meter. One leg connects at the lug behind the battery and the other at the horn relay. It measures the current through the feed wire to the horn relay. Make sure you install a fuse or fusible link in each wire.
They are pretty much useless. Do yourself a favor and install a volt meter somewhere so you can see it actually charging.

 

[Jim Streib]

Ok, gotta ask, why the upgrade in alternator output ?.

Do you need the extra amps or are you wanting better low RPM output or ??????.

When you upgrade to a larger output alternator you have to watch where you connect it into the car, and then where added accessories are getting power from.

The factory charging circuit was mostly designed to handle around 65A or so. GM ran the minimum sized wire needed to support this and now if you put in a 100A alternator and tie into the existing wiring at the same point the old alternator was using AND you are still drawing 65A or less, you will be fine BUT if now you add let's say a 35A draw off of the battery and the car still requires the initial 65A it needed before, then the charge wire from the alternator to the battery designed for 65A will be overloaded.

Now this is an extreme scenario BUT it can happen.

Also too, when you upgrade the alternator you also have to upgrade ground cabling.

I'm also in that boat that supports using a volt meter and getting away from a shunt style or full flow style ammeter gauge setup.

Jim

 

[mike pratola]

Ok, gotta ask, why the upgrade in alternator output ?.

Do you need the extra amps or are you wanting better low RPM output or ??????.

When you upgrade to a larger output alternator you have to watch where you connect it into the car, and then where added accessories are getting power from.

The factory charging circuit was mostly designed to handle around 65A or so. GM ran the minimum sized wire needed to support this and now if you put in a 100A alternator and tie into the existing wiring at the same point the old alternator was using AND you are still drawing 65A or less, you will be fine BUT if now you add let's say a 35A draw off of the battery and the car still requires the initial 65A it needed before, then the charge wire from the alternator to the battery designed for 65A will be overloaded.

Now this is an extreme scenario BUT it can happen.

Also too, when you upgrade the alternator you also have to upgrade ground cabling.

I'm also in that boat that supports using a volt meter and getting away from a shunt style or full flow style ammeter gauge setup.

Jim

I upgraded to the 100 amp alternator in anticipation of installing the Sniper fuel injection system and probably upgrading the headlights. I've installed heavy duty straps and heaver gauge wires from the alternator per the Tuff Stuff installation guide. I went with the factory style gauge cluster because I like that look and didn't want to install a row of knee knocker gauges under the dash and a tach on the steering collum. If this was a full flow meter I'm pretty sure the OE wires going to the amp gauge would be a smoke test if hit with 65 amps. I like the idea of fusing it, thought about the possibility of adding a shunt or induction coil but haven't gone down that rabbit hole yet.

 

[69SS454]

It is not a full current meter but the wires are small and connect to large current carring wires that create a potential for bad things to happen.