FC Coil(s?) on my 12a streetport?
11-01-15, 04:16 PM
#1
"Smells like coolant.."
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FC Coil(s?) on my 12a streetport?
Is this possible? As the title suggests, I'm running a 12a streetport with a modded nikki carb and I'm trying to think of little ideas i can do to give her a little more oomph on the top end as i can feel she still has a lot more to give. I have a wrecked FC sitting out back that runs great but that isn't road worthy anymore. I don't know what to do with it just yet but i started thinking that, rather than buy a whole new msd ignition system, what if i could modify the absolutely massive trailing coil on the fc to work on my fb? Is this possible? Has it been done? I understand the setup, two plugs on the fc VS one on the fb and all that, but is there a way to make it work? If it's already been done and posted, sorry, i did some searching and couldn't find anything on the subject. Shoot me your thoughts! 
11-01-15, 05:40 PM
#3
I use an fc leading coil. At 1st I ran it with the stock ignitor, but they won't hold up long. Now I use an MSD box to feed the coil and it works very well.
As Jeff20b said, search. There are several paths to direct fire, none of them particularly expensive.
As Jeff20b said, search. There are several paths to direct fire, none of them particularly expensive.
11-01-15, 07:22 PM
#4
Fellow forum user PercentSevenC tried an FC leading coil in his car and had the same issue with it. It burned out the stock FB ignitor and left him stranded at a rotary meet. Luckily I was there and was able to make the trailing ignition, which was still stock, fire the leading plugs and he got home just fine. After that, the 2nd gen coil and any traces of it were removed with prejudice. Then DLIDFIS went in and the differences were like night and day compared not only to stock through the cap, but also compared to the 2nd gen coil setup.
I'm telling you, DLIDFIS is best.
However I will say this. I never had a chance to test an MSD hooked to a 2nd gen leading coil. It probably works ok as the MSD box is strong enough to handle most coils you hook up to it. However, it makes the coil behave more like a basic step-up transformer and less like a Kettering system as it was originally designed to be. This could cause the insulator on the windings to eventually break down and short internally. This is due to the 400 volt output of the MSD hitting the coil where 12 to 14 volts is expected. Of course the field breakdown of the Kettering system does push upwards of 400 volts into the secondary windings, so maybe you'll be fine for a long time. Don't know because I only had an MSD for a short time. I tested DLIDFIS soon after and liked it a lot better.
To make a long story short, it's best to use a coil designed with a capacitive discharge ignition, or CID like what the MSD uses, if you choose to go that route. I personally wouldn't bother these days unless I find the spark from DLIDFIS to not be adequate in boost. So far so good though, at up to 10psi I think.
I'm telling you, DLIDFIS is best.
However I will say this. I never had a chance to test an MSD hooked to a 2nd gen leading coil. It probably works ok as the MSD box is strong enough to handle most coils you hook up to it. However, it makes the coil behave more like a basic step-up transformer and less like a Kettering system as it was originally designed to be. This could cause the insulator on the windings to eventually break down and short internally. This is due to the 400 volt output of the MSD hitting the coil where 12 to 14 volts is expected. Of course the field breakdown of the Kettering system does push upwards of 400 volts into the secondary windings, so maybe you'll be fine for a long time. Don't know because I only had an MSD for a short time. I tested DLIDFIS soon after and liked it a lot better.
To make a long story short, it's best to use a coil designed with a capacitive discharge ignition, or CID like what the MSD uses, if you choose to go that route. I personally wouldn't bother these days unless I find the spark from DLIDFIS to not be adequate in boost. So far so good though, at up to 10psi I think.
Last edited by Jeff20B; 11-01-15 at 07:24 PM.
11-02-15, 08:03 PM
#5
"Smells like coolant.."
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So after doing lots of research, I've got a pretty good idea of what i need to do. There's just one thing I'm hung up on: There's no way I'm finding a third FB coil anywhere near me and don't really have the funds to try and find one on ebay or some such. Do i try running the FC coil to fire the two leadings and use my one fb coil for the trailings, keeping the second for a spare? I think this is what you mentioned in the previous post but I just want to make sure i have all my bases covered before i start tearing into ****. Thanks for your help
11-03-15, 07:56 AM
#6
Waffles - hmmm good
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I just finished re-configuring my ignition to do just that. I use the FC coil to drive the leading
plugs and then use the single TFI coil to drive the trailing. The FC coil works as well as the 2 TFI
coil setup I used to have. I'll be posting up more commentary and pics in my thread https://www.rx7club.com/1st-generati...fidfis-894669/
later this week on the reconfiguration and how it went.
plugs and then use the single TFI coil to drive the trailing. The FC coil works as well as the 2 TFI
coil setup I used to have. I'll be posting up more commentary and pics in my thread https://www.rx7club.com/1st-generati...fidfis-894669/
later this week on the reconfiguration and how it went.
11-03-15, 10:21 AM
#7
I just finished re-configuring my ignition to do just that. I use the FC coil to drive the leading plugs and then use the single TFI coil to drive the trailing. The FC coil works as well as the 2 TFI coil setup I used to have. I'll be posting up more commentary and pics in my thread https://www.rx7club.com/1st-generati...fidfis-894669/ later this week on the reconfiguration and how it went.
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