Factory Supplied Group Size Battery - 1958 Cadillac

[Jon S]

 I’ve been using a group size 27 in my 1958 Cadillac but was just curious if anybody knows what group size was provided in the car from the factory?

[savemy67]

Hello Jon,

My old '54 - '63 Chilton lists the '58 Cadillac as coming with a 3KM group size battery.  This size has probably been replaced with the size 27 as you indicated. 

Christopher Winter

[Jon S]

Thank you

[fishnjim]

Most likely, anything that fits the factory battery box that's made today will be "bigger" in CCA than what they came with.   So no comparison, per se, except physical size.   Battery groups came later.
The old "tar tops" are still made but the "fake" ones with the new insides are better.   Frankly, that's a purist thing that I don't worry about.   I think anything over about 780 CCA would suffice.   A lot depends on how tight the motor is and shape of the electrical system/starter.
It should be in the documentation.   Go to GH heritage archives and download the "specifications".   I'm too lazy today to look.   

[fishnjim]

FYI: I found this in my papers from the spec manual.
It shows the factory battery.
I'm running a 27 Duracell.