Topic: Battery
in Forum: C3 Electrical
Already a Member?
Click Here to Login
Not yet a Member?
Click Here to Register for Free!
SPONSOR AD:: (Our Sponsors help support C3VR)
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Depends on your options. Do you have A/C, power winders, rear defrog, etc? You would want at least a 65 amp...
Joel Adams
C3VR Lifetime Member #56 
My Link 
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Lifetime MemberLanoka Harbor, NJ - USA
Joined: 12/21/2006
Posts: 828
Vette(s): 1975 metallic blue coupe with t-tops,L48, t/t steering, black leather interior. 1990 L98, white/red leather interior, auto,a/c
my 75 has p/w, a/c (not working right now). no rear defogger. the book
calls for a 61 amp with a/c and a 42 without. when i bought the
car there was a 55 amp in it and it took a long time to replenish
the battery plus windows seemed to be sluggush. i installed a 75 amp
and it made a big difference in the windows and replenishing the
battery. will be installing an aluminium radiator with dual fans so i
will probably up it to 100 amp. joel is right, the minimum i would
start with would be a 65 amp.
LIFETIME MEMBER #97
THE DYNAMIC DUO
THE DYNAMIC DUO
Lifetime MemberHOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
While you're at it, make sure your cales and connections are clean and in good shape. A lot of mis-diagnosed electrical problems were the result of gremlins in the cables....
LukesVette Homepage
Veteran of Operation Iraqi Freedom
101st Airborne(AirAssault!)
God Bless America
Support Our Troops 
Thanks guys my plan is to replace the alternator with a 65 amp. I do have A/C and power windows. But first I will have the alt check to see what amp it is and if it is working. Is there something on the alt that would tell me what amp it is?
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
It will be stamped with the amp rating. Look on the top, front case, by the "ear" that the top adjustment bolt goes thru. You'll see the amp rating, a part number, and a date code. If it has ever been rebuilt, this may mean nothing.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
OK replace the alternator today and it does work fine. I am hoping the battery does not go dead and that was the problem with the battery. I did put a altimeter on it and it read 12.30 at idle but did not go over 14 when I rev the engine up? Could there be a problem there?
Lifetime MemberHOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
Up to 14 should be ok. Run some accessories, headlights, etc and see if you're still between 12.5 and 13.5 volts at cruising rpm.
LukesVette Homepage
Veteran of Operation Iraqi Freedom
101st Airborne(AirAssault!)
God Bless America
Support Our Troops
in Forum: C3 Electrical
SPONSOR AD: (Our Sponsors help support C3VR)