Guys,

I have a 1972 Chevelle 4dr that origionally had A/C, AM radio and an otherwise standard interior. I assumed that I had a 63 amp alternator due to the A/C.

I now have an electric fan and am about to be feeding twin fuel pumps which will, in turn, be feeding "XFI" EFI.

My question is: Is it likely that if I do have a 63 amp alternator that it will power all that? The alternator pushed about 30 amps when the fan running, at night, with headlights on. That was what the alternator saw as maximum load. The only time I ever saw the alternator go higher was after prolonged cranking. Then it would typically hit 45 amps until the battery was sated.

Unfortunately I don't know what the pumps will draw at this time nor is the car at my fingertips to look at the alternator. The a/c has been permanently removed.


Bill

My question is: Is it likely that if I do have a 63 amp alternator that it will power all that?
At higher RPM's maybe, at lower RPMs and idle no.

The alternator pushed about 30 amps when the fan running, at night, with headlights on. That was what the alternator saw as maximum load.
How did you measure this? And at what RPM.
The only time I ever saw the alternator go higher was after prolonged cranking. Then it would typically hit 45 amps until the battery was sated.
A higher battery charging rate is normal is the battery is run down some.

Your alternator can probably be rebuilt to produce 100 amps.
A local shop should be able to do that for a reasonable price.

With the additional load you need to increase the size of the charging wire from alternator to the distribution point and from there to the starter/battery.

The fuel pumps should be operated by relay with fuses.

Where are you taking power for the fans?

no it won't carry the extra load. Even upgrading your alt to 100 amps will be a problem at low RPM. You need an alt designed to have a better low RPM out put, like a CS130 or a CS144. Pay attention to Verle on the relays. Mark

Your alternator can probably be rebuilt to produce 100 amps.
A local shop should be able to do that for a reasonable price.

With the additional load you need to increase the size of the charging wire from alternator to the distribution point and from there to the starter/battery.

The fuel pumps should be operated by relay with fuses.

Where are you taking power for the fans?

undee70ss I have an amp meter mounted under dash with the rest of my gauges. I see the amp draw at all times. It's fed by 10GA wire.

Verle, Both fuel pumps and the fan are operated via relays that have all connections soldered and insulated with heat shrink. Electrically the system is up to the task. The only unknown here is the alternator as it's an externally regulated alternator. I'll look in to getting my alternator upgraded however I suspect that I would be better served by a higher capacity alternator. I am not familiar with a CS130 or a CS144. Do they mount in the same fashion as my present alternator?

As soon as the car is finished I'll post pics but right now everything is a mess. I expect to be driving the car next week after some dyno work. Fingers crossed!

there is a CS130 that will mount right up without any changes. You can usually even use the same belt. The CS144 is larger and may require mounting changes.

More than you ever wanted to know about alternators :D

http://oljeep.com/gw/alt/edge_Alternator_Theory.html#Section_2