To Big 3 or not on 94 Chevy with 5.7??

[pose]

Hi there.

I have a 94 Chevy C1500 Silverado with the 5.7 (350). I just put in a new battery yesterday and am thinking of doing the Big 3 upgrade. I have a CS 130 alternator which I think is 105 amps and looks like it was installed within the last year.

The volt meter in the dash starts out at 14 volts as expected but will go as low as between 14 and the hash mark between 9 & 14. I checked it with my voltmeter on my jump pack and it shows 14.4 at idle with everything turned on. I'm not surprised that the gauge may be inaccurate.

Any insight would be greatly appreciated.

Thanks in advance.

 

[RawbDidIt]

Hi there.

I have a 94 Chevy C1500 Silverado with the 5.7 (350). I just put in a new battery yesterday and am thinking of doing the Big 3 upgrade. I have a CS 130 alternator which I think is 105 amps and looks like it was installed within the last year.

The volt meter in the dash starts out at 14 volts as expected but will go as low as between 14 and the hash mark between 9 & 14. I checked it with my voltmeter on my jump pack and it shows 14.4 at idle with everything turned on. I'm not surprised that the gauge may be inaccurate.

Any insight would be greatly appreciated.

Thanks in advance.

The gages on these trucks aren't super accurate. With that said, you may still benefit from a big 3 upgrade. The biggest indicator will be the voltage at the input to the main distribution. In my 97, that's in the engine fuse box, I don't believe your 94 has that, but there should be a main fuse or relay center that is directly connected to the positive terminal. That's where you're going to see voltage drop, and I believe that's also where the gage reads the voltage. I was reading 14.4 all day at the battery and the alternator, but only getting about 13.7 at the main fuse box with a new 250 A alternator. Upgraded the wire connecting it and got 14.2 IIRC. Upgraded ground and alternator wire and it crept up even more. If you're measuring at the battery, you're only going to see voltage drop if the system is overloaded. That would indicate you need a better alternator, or a second battery to ballast during peak use. There voltage drop you're looking for is the main draw furthest from the power source.

Sent from my SM-G965U using Tapatalk

 

[pose]

I see what you're saying. My truck has the strip on the firewall that acts as a distribution block. I'll probably start with the ground straps and alternator to battery connections. Might be worthwhile to make a beefier distribution block or even get one out a 95-up truck since they have the dual positive cables.

Thanks for the explanation.

 

[Jglew82]

The good thing about upgrading your cables, is there is no downside! I'd consider it preventive maintenance, and then you'll have peace of mind.

 

[kennythewelder]

I did my truck about 3 years ago. Its a grate up grade. I also added 2 more grounds. The big 3 is

1 from alt to pos bat with fuze
2 from alt case to neg bat
3 from neg to frame of truck
I also added 2 more grounds
4 from bat to engine block
5 from ground to truck cab body
I use #2 welding led, as I am a welder, and that is easy access for me. The fuze I used was 120 amp. I saw a big improvement in charging. Although I still see my gauge go down to around 10 while at idle with everything on including electric fans, AC , ECT, the recovery is much quicker. It is a win win doing the up grade.

 

[Jglew82]

In addition to the big three (and I definitely second using welding cables) I also added ground straps further back: trans case to frame, frame to bed close to the fuel tank (also a good time to double check your ground for the sending unit/pump). These may not have been totally necessary, but I did an LQ9 swap and let's just say you can never have too many grounds for those platforms.

 

[kennythewelder]

The way I was able to add all of those os by welding 2 3/8 bolts together on the bolt head. This gives you plenty of room to add more cables. On the pos, I had enough room for 1 more wire.

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[pose]

I recently added a ground from the battery to the frame and a ground from the alternator case to the frame. I've already noticed a difference on the volt meter in the cluster (much more stable). Will be looking at my father's 95 Silverado since it has the tbi set-up and the fuse/relay center under the hood. That way I can do something similar on my 94.

 

[PlayingWithTBI]

I'm thinking about doing the "Big 3" on my 88. It's a little different, I don't have a fuse box in the engine bay, it's inside below and to the left of the steering wheel. I got prices on 1/0 for main pos and neg and 4AWG for others, 120A in-line fuse holder, lugs, and these battery terminals (kinda like what @kennythewelder did). Total price ~$150, @5vortec7 does the whole thing for $200 so, IMO it's pretty much worth it to have him do it.

https://www.amazon.com/gp/product/B000CQI23Y/ref=ox_sc_saved_title_5?smid=ATVPDKIKX0DER&psc=1

 

[TechNova]

I see what you're saying. My truck has the strip on the firewall that acts as a distribution block. I'll probably start with the ground straps and alternator to battery connections. Might be worthwhile to make a beefier distribution block or even get one out a 95-up truck since they have the dual positive cables.

Thanks for the explanation.

You might want to rethink using the OEM double positive connection at the battery. The red plastic can cause problems with getting good connections at the battery. Also, the way the cables were routed caused the cable weight to force the bolt loose as the truck was driven.
I removed mine two days ago and made new cables with #2 weld cable and crimped,soldered, shrink wrapped ends. I routed them to be straight down or slightly to the side that would tighten the bolt from their weight. Special bolts, a 3/8 bolt and jamb nut or welded bolts as shown above help a lot when you have to get battery charger clamps on them vs, the small factory bolts.