spark plug confusion?!!
04-07-2006, 06:43 PM
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spark plug confusion?!!
Hello all- I purchased a 67 BB 390 HP 3 yrs ago and have slowly been restoring. The car is experiencing some dieseling and I'm not sure correct spark plugs are installed. Currently there are Autolite 104's installed. I looked up AC delco site are they recommend R43 xls. When I compare plugs the r43 is significantly longer at the insulator end than the Autolite. I've searched archives and it looks like the most popular plug is a r45. Help, i don't want to put too cold of a plug or the wrong length. Any help appreciated. GW
04-07-2006, 08:47 PM
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1967 390 hp 427 Spark plugs
GREGWOLFRAM - Hi. My old factory service manual specifies "AC 43 N" as the standard plug for the 390 hp 427, and 42 N as the "cold" plug. Sorry, I don't know what the "N" refers to........maybe someone else here does.
Best Regards,
Bob S.
Best Regards,
Bob S.
04-07-2006, 09:46 PM
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If you have the old factory ignition and coil, be careful about substiuting resistor plugs (r45xls) for nonresistor (43n) - if you have resistor wires too - the old coil can be overloaded.
04-07-2006, 09:56 PM
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Yes, thank you Bob. My service manual spec out the spark plg as a r43n as well, however, you can't buy these over the counter any longer- atleast that I was able to locate.
MagicV8 thank you for the info. I do bevieve my coil is an original. I'm not sure about the wires, but they do look original! How can you tell about wires and coil- any hints appreciated.
Greg
MagicV8 thank you for the info. I do bevieve my coil is an original. I'm not sure about the wires, but they do look original! How can you tell about wires and coil- any hints appreciated.
Greg
04-07-2006, 11:22 PM
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I'd be real surprised if the wires were original.
According to the NCRS JG, astandard 390/427 has a coil with 232 or 262 embossed on the sidein raised letters.
If your L36 has transistor ignition, the coil is 210, 261, or 231 embossed on it.
The shielded wires are generally carbon core radio suppression wires, since the factory intended them to be used with non resistor plugs. If you have an original coil on your car and are using resistor plugs with high resistance (nonmetalic core) wires, IMO remove the expensive to replace original coil and put in an auto store replacement. Use the original coil for judging events only.
PS I would give the same advice to SB engine car owners. Those cars also came with nonresistor plugs.
According to the NCRS JG, astandard 390/427 has a coil with 232 or 262 embossed on the sidein raised letters.
If your L36 has transistor ignition, the coil is 210, 261, or 231 embossed on it.
The shielded wires are generally carbon core radio suppression wires, since the factory intended them to be used with non resistor plugs. If you have an original coil on your car and are using resistor plugs with high resistance (nonmetalic core) wires, IMO remove the expensive to replace original coil and put in an auto store replacement. Use the original coil for judging events only.
PS I would give the same advice to SB engine car owners. Those cars also came with nonresistor plugs.
04-08-2006, 08:01 AM
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Originally Posted by gregwolfram
Yes, thank you Bob. My service manual spec out the spark plg as a r43n as well, however, you can't buy these over the counter any longer- atleast that I was able to locate.
MagicV8 thank you for the info. I do bevieve my coil is an original. I'm not sure about the wires, but they do look original! How can you tell about wires and coil- any hints appreciated.
Greg
MagicV8 thank you for the info. I do bevieve my coil is an original. I'm not sure about the wires, but they do look original! How can you tell about wires and coil- any hints appreciated.
Greg
I use the R45 XLS in my BB. They work fine. You may find anything colder than this will foul or misfire.
