Team Camaro Tech banner
1 - 7 of 7 Posts

·
Premium Member
68 SS/RS, 468 BB 4 speed, 3.73 Posi, new paint, motor mods , trans and diff assembly. 2" Drop
Joined
·
709 Posts
Discussion Starter · #1 ·
In my 68 BBC Camaro is what appears to be just a chrome 3 wire alternator. I recently converted to serpentine belt system. I have also hooked up the stereo amp that was in the trunk as well as added an aluminum radiator with dual SPAL fans along with a Dapper LED headlight conversion (actually all lights in the car are now 100% LED), and just added a MSD HEI distributor.
On the way home from the dizzy being installed and carb/engine tuned, everything was normal. It was hot when I got home, but noticed in driveway idling when the fans came on, the OEM repop gauge needle dropped just below the half way mark (usually rides just above middle mark.) I threw my VOM on it and it was still reading 13.9 and if I raised the idle to like 1k it went to 14.5ish.
Is it possible the alt is not putting out enough or is it most likely just a slow reading gauge? If I raise it to 750 RPMs plus, it reads as normal. The tuner lowered the idle to 650, can that be too low?
 

·
Registered
Joined
·
1,510 Posts
Is it possible the alt is not putting out enough or is it most likely just a slow reading gauge? If I raise it to 750 RPMs plus, it reads as normal. The tuner lowered the idle to 650, can that be too low?
Alternator output depends on how fast it is being spun. They all have an output curve. Bigger does not always mean higher lower RPM output.



Jim
 

·
Premium Member
68 SS/RS, 468 BB 4 speed, 3.73 Posi, new paint, motor mods , trans and diff assembly. 2" Drop
Joined
·
709 Posts
Discussion Starter · #4 ·
I was thinking output at idle. Especially with lights, stereo and fans come on. Thats when I notice the fluctuation
 

·
Premium Member
1969 Camaro Restomod
Joined
·
1,890 Posts
I’ve got a Powermaster as well, IIRC it’s rated at about 100 amps at idle, 150 at highway speed. Think the factory test ticket said 153 peak.
 

·
Registered
Joined
·
149 Posts
You need to know what your max amp draw is before buying just any old alternator. How many amps do the fans draw? What other items have high amp draw? Ac? Stereo will take its slice of pie. High amp alternators in the 60’s were 63 I believe. You definitely need closer to 100. For now, move it back to 750
 

·
Registered
Joined
·
3,851 Posts
I was thinking output at idle. Especially with lights, stereo and fans come on. Thats when I notice the fluctuation
As noted, add up your loads given you have aftermarket stereo, EL fans, etc. Likely 100 or 135 amp ALT

They should show spec at what rpm = x amp output

It will help, specifically headlight, actually all lights, if you install a headlight relay harness. Plug & play, no cutting stock wires and helps considerably headlight brightness. I bought mine from Speedway but other sources have them for around $32
 
1 - 7 of 7 Posts
Top