Just wired up my FC coil last week. One question... Why does it sputter for the first 5-6 seconds on a cold start? It sometimes puts out a small backfire as soon as you turn the key. It seems to smoke a bit as well until the engine has been driven down the road a couple hundred feet.

I am using factory 81-85 12a plugs. Should I be using FC leading plugs? Should the timing be advanced or retarded from the setting I had on the stock 12a coil? Did I wire something wrong? Is one of my igniters bad?

After it runs for 5-6 seconds it runs great. Feels more powerful and smoother. Seems to be giving me a few more miles to this tank of gas too. Screeches the tires in 2nd and 3rd gear a little louder. Any input would be appreciated.

 

Nobody has any ideas?

The way it starts up reminds me of how it ran when the points gaps were off. It wouldnt be a sticky seal on one rotor would it?

 

I'm not running a custom ignition setup, but have found over the years that fouled plugs will tend to give you that 'wonky' running until the engine temp gets up and the fouling has a chance to burn off after a minute or two. Could be your problem, as well.

Anytime you have oil being injected into an engine (like ours, even if you pre-mix, same thing), you're going to have oil carbon residue that accumulates on all surfaces open to the combustion cycle - including spark plugs. When this residue builds up is after the engine cools down with 'wet' fuel/oil mixture on it. The high temps remaining in an engine core will dehydrate the fuel/oil and what's left is a gummy mixture of carbon. This carbon conducts electricity pretty well, so when you go to start it next time, it prevents a clean spark jump across the gap. Sometimes you only get ignition from the trailing, which is what gives you that lumpy idle on cold start.

You'll note that the trailing igntion plug holes are tiny in comparison to the full bore of lead plug holes - for this reason, the trailing tends to foul less often.

Could try going to a hotter spark plug, which will retain more of the heat of combustion and help to burn off oil residue, but that probably WON'T help your cold-start lumpiness.

I consider it an endearing quality of an old rotary, much like the heavy 'BRAP' you get when you blip it when cold. My neighbors kids swear I keep a racecar in my garage...

 

i dont know what to tell you when i did mine it started up easier, warmed up faster, ran better, there was a difference not extremely huge, but you could still tell.

you could run some seafoam in there clean up the inside of the engine and see if that helps by getting some of the excess carbon.

2nd gen plugs are not NEEDED but you can put some on the leading side. i'm running the cold 2nd gen plugs since most of my driving is hwy, and it helps with mileage quite a bit.

i think i did have to move the timing just a bit when i installed the coil, but i can't remember, it wont hurt to check it and see were you're at.

 

Plugs are 3000 miles old. I even swapped the leading platinum plugs out of my FC temporarily (only a few hundred miles on them) and they did the same thing as the BR8 1st gen plugs. I'm running a can of seafoam in 4-5 gallons of gasoline right now in it so maybe it will help. I was wondering if it could be a sticky float...

Just to recap on the 2gdfis...

-You still need to run the 1st gen electronic dizzy condenser right?
-You keep the resister on the 2nd gen coil, but no additional resister/relay is needed?
-You use the factory spec j-109s? No modifications needed to them?


I just wonder if the coil is on its way out. My wiring is rock solid. Voltage is the same on the battery as it is on the coil terminals.

 

sounds correct man, all you do is power up from the leading coil, no other mods needed, dizzy and everything else stays intact.