Coil - 6v or 12v

May have fried my coil on '65 CJ5. Has been converted to 12v. Cannot find a ballast resistor between the ignition and coil. Should I buy a 12v coil with a built in ballast resistor or standard 12v coil and add a ballast resistor?

 

I'd buy a ballast resistor. I'd sell one from a '70s Dodge car when somebody wanted a generic. Cheap.

 

Thanks, but already have a new ballast resistor. Just wanted to make sure I bought the correct coil. The coils listed at autozone for the '65 CJ5 are, of course, 6v. Just want to make sure I should use the ballast resistor and buy a 12v coil without internal ballast resistor? What year Jeeps used a 12v coil w/no ballast resistor (doubt if the kid at autozone will know) Or since buying a new coil anyway, should I buy one with a built in ballast resistor, and leave my new ballst resistor on the shelf?

 

Standard UC12 or equivalent.

http://www.rockauto.com/catalog/moreinfo.php?pk=47701

Up to you if you pick an external ballast resistor, or internal. Functionally equivalent. An external resistor moves the resistor heat outside of the coil body, so I think that's a slight advantage. Additional connections for the external resistor ar a disadvantage - any mechanical connection is a slight liability.

 

I used a BWD #RU4 ballast resistor, looks exactly like the original, has been working fine.

An external ballast can be hacked with a bypass switch, to give a hotter spark for 'emergency' starting, if needed. A lot of conventional ignition switches worked that way full-time, it compensates for voltage drop when cranking the starter.

 

None of the big 3 auto part stores here list a UC12 part number for a 12v coil. What vehicle can I specify that would have had an appropriate coil - 12v - no internal ballast resistor? Mid-60s mopar?

 

How about Jeep Cj5? Late sixties.

 

Wow. They can't cross-reference a Standard number? Did you tell them it's a competitor's number and ask to cross it to their parts? That's either incompetent or willfully ignorant. Or maybe they are idiots.

I pointed to the Standard coil, because Standard parts (SMP - Standard Motor Products) are available everywhere, they are good quality parts, and you'll know what you are getting. They also have a UC12T now (cheap - avoid) and they make a UC12X super-quality coil.

Go to RockAuto, select part number search, enter UC12, select it, click on the highlighted part and get a list of applications.

AMERICAN MOTORS (1958 - 1979)
ASTON MARTIN (1967 - 1971)
BMW 1974
BUICK (1953 - 1979)
CADILLAC (1953 - 1974)
CHECKER (1961 - 1974)
CHEVROLET (1955 - 1990)
CHRYSLER (1955 - 1978)
DESOTO (1956 - 1960)
DODGE (1953 - 1989)
EAGLE (1990 - 1992)
FIAT (1978 - 1981)
FORD (1972 - 1978)
GEO (1989 - 1990)
GMC (1955 - 1990)
HILLMAN (1962 - 1965)
HONDA (1973 - 1987)
HYUNDAI (1983 - 1987)
INTERNATIONAL (1957 - 1980)
ISUZU (1981 - 1985)
JEEP (1963 - 1977)
LANCIA (1976 - 1978)
LOTUS (1976 - 1979)
MAZDA (1971 - 1987)
MERCEDES-BENZ (1966 - 1971)
MERCURY (1971 - 1974)
MITSUBISHI (1983 - 1989)
NASH (1955 - 1956)
NISSAN (1980 - 1987)
OLDSMOBILE (1953 - 1974)
PLYMOUTH (1955 - 1987)
PONTIAC (1955 - 1974)
RENAULT (1972 - 1980)
ROLLS ROYCE 1974
STUDEBAKER (1960 - 1965)
SUBARU (1977 - 1987)
SUZUKI (1986 - 1990)
TOYOTA (1967 - 1992)
VOLVO (1981 - 1988)

I would buy from somewhere else. RockAuto is fast and has good prices. Or your local Napa store.

Or go to an independent. Every independent store will carry Standard.