The stock Honda coil was rated at 15kV when brand new 35 plus years ago and with age has surely degraded. The answer to getting good spark voltage lies in starting with a good coil. The CDI system is spec'd to use .55 ohm primary resistance coil and although it seems to be OK to use one that's 1 ohm or less it's best to stick to spec. Original spec in 1978 was .3 ohm.
GM D555/576 coils from the mid '80's thru 2006 fit the bill nicely.
The GM engines that seem to require the best coil output are the 2000-2005 Bonneville SSEi versions. Here's a 20011 dated post comparing versions http://www.pontiacbonnevilleclub.com/forum/2000-2005-other-than-gxp/topic29036.html I'm sure that there have been more version created but not all are the same. Lately you can buy 3 of this type coil for @$20 on eBay, probably need all 3 to find a half way decent one.
First issue is the coil does not fit under the tank like stock. If you're willing to sacrifice looks for function this is the way to go.
You can use the original front coil mount hole for one end of the coil, longer bolt needed.
Then make a bracket to extend from the original coil rear mounting hole to the other coil mount hole. This prevents the coil from vibrating too much and cracking.
These are what I used to mount mine
The white spacer is to give the primary wire clearance from the frame, black spacer for the bracket to the frame so the bracket is flat. Long bolt for the coil and spacer to frame. 1 short fot coil to bracket and the other for bracket thru spacer to frame.
Second issue is the primary wires. You can cut the wires off an old coil so you have the connector or Vintage Connections can sell you the pieces needed. Now for attaching the wires to the coil. It's a small female spade connector inside. I don't have a part number to look for there. That's the plug in version. Next are 2 solder versions.
I chose to remove the white plastic cap to get access to the terminals to solder the wires on. The cap pries off and the tabs will break so plan on gluing back in place. Drill the terminal holes big enough for the wires to pass thru. Put the wires thru and solder the wires to the terminals. It doesn't matter which wire goes where. Glue the cap in place and seal it with liquid electrical tape. You'll want to set the spacer in place beforehand.
Other choice is mark the coil for an exact location of where the terminals are on the top side of the coil. VERY carefully drill in just far enough to get to the terminals. TOO fast or far and the terminals are damaged or torn loose. The solder the wires to the terminals and seal the holes with liquid electrical tape.
Plug Wires: The NGK plug caps will just barely accept 8mm plug wires. You can use a standard graphite core GM plug wire, expect them to last a year or so since they're exposed to the elements and prone to braking internally. Ideally you want wire core plug wires, you're unlikely to find them in the local auto parts store. Some of the speed shops or custom truck shops have them. Originally I used some car wires but they failed after the first year. I ordered a pair of Taylor wires but it appears they only sell set now. An internet search for solid core wire will give results for you. http://www.taylorvertex.com/product-search/?id=220444&sID=61
Pros: Good spark voltage, wider plug gap (I use .032"), smoother idle because the mixture is burning better with the hotter spark
Cons: It's not good looking
Some pictures that may answer your questions
GM D555/576 coils from the mid '80's thru 2006 fit the bill nicely.
The GM engines that seem to require the best coil output are the 2000-2005 Bonneville SSEi versions. Here's a 20011 dated post comparing versions http://www.pontiacbonnevilleclub.com/forum/2000-2005-other-than-gxp/topic29036.html I'm sure that there have been more version created but not all are the same. Lately you can buy 3 of this type coil for @$20 on eBay, probably need all 3 to find a half way decent one.
First issue is the coil does not fit under the tank like stock. If you're willing to sacrifice looks for function this is the way to go.
You can use the original front coil mount hole for one end of the coil, longer bolt needed.
Then make a bracket to extend from the original coil rear mounting hole to the other coil mount hole. This prevents the coil from vibrating too much and cracking.
These are what I used to mount mine
The white spacer is to give the primary wire clearance from the frame, black spacer for the bracket to the frame so the bracket is flat. Long bolt for the coil and spacer to frame. 1 short fot coil to bracket and the other for bracket thru spacer to frame.
Second issue is the primary wires. You can cut the wires off an old coil so you have the connector or Vintage Connections can sell you the pieces needed. Now for attaching the wires to the coil. It's a small female spade connector inside. I don't have a part number to look for there. That's the plug in version. Next are 2 solder versions.
I chose to remove the white plastic cap to get access to the terminals to solder the wires on. The cap pries off and the tabs will break so plan on gluing back in place. Drill the terminal holes big enough for the wires to pass thru. Put the wires thru and solder the wires to the terminals. It doesn't matter which wire goes where. Glue the cap in place and seal it with liquid electrical tape. You'll want to set the spacer in place beforehand.
Other choice is mark the coil for an exact location of where the terminals are on the top side of the coil. VERY carefully drill in just far enough to get to the terminals. TOO fast or far and the terminals are damaged or torn loose. The solder the wires to the terminals and seal the holes with liquid electrical tape.
Plug Wires: The NGK plug caps will just barely accept 8mm plug wires. You can use a standard graphite core GM plug wire, expect them to last a year or so since they're exposed to the elements and prone to braking internally. Ideally you want wire core plug wires, you're unlikely to find them in the local auto parts store. Some of the speed shops or custom truck shops have them. Originally I used some car wires but they failed after the first year. I ordered a pair of Taylor wires but it appears they only sell set now. An internet search for solid core wire will give results for you. http://www.taylorvertex.com/product-search/?id=220444&sID=61
Pros: Good spark voltage, wider plug gap (I use .032"), smoother idle because the mixture is burning better with the hotter spark
Cons: It's not good looking
Some pictures that may answer your questions
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