Any dangers to using FC leading spark plugs?
 

79 SA with 12a Nikki, 2 1/2" exhaust, header, Holley electric fuel pump...

This car came with 8 NGK BR9ES plugs. I absolutely hate these plugs! They foul up like crazy to where it doesn't want to start and is erratic at idle. On a whim I swapped in a pair of 2nd gen LEADING 7 range plugs I had laying around from my last FC project. I kept the BR9ES plugs in as TRAILING. BAM started right up and the idle was super smooth and rock solid at 800 RPM after a little tunnig. No pops, no stutters, just smooth. It revs great. I drove it up and down the street (no hot rodding, just cruising through the gears) and it drove fantastic.

My question is I've seen threads here and there about using 2nd gen plugs. I just want to make sure it doesn't pose any threat to my seals or anything by being a more powerful spark.

Are you still running the points ignition?

Yes. Seemed to run really good. Just don't want to chip a seal or something.

2nd gen plugs shouldn't chip the seals, since theyre designed for the same type of engine.

I didn't hammer it on my drive or anything. I think it feels really good. Feels more like a 2nd gen the way it drives now. Not so much like a jerky fidgety out of tune carb'd car.

I've been running BUR7EQ leading plugs through the distributor with no problems. I'm sure it would be even better with direct-fire ignition.

If you want to get the full benefit of those plugs then I recommend that you upgrade to the FB electronic ignition and run the 2nd gen leading coil.

In my SE I gained 1.3 MPG by running the 2nd gen leading coil. This has been verified twice on test drives recording the mileage with the 2nd gen leading coil and then with the stock FB coil. :-)

Good to hear. I plan on buying an FC coil to do the direct fire setup, but for now I just want to get it drivable and reliable. My current setup seems to be all of the above.

79 points, 2nd gen LEADING 7 spark plugs, 1st gen TRAILING 9 spark plugs, 12a with Nikki and cold air ram modification, emissions removed, new air filter, Holley electronic fuel pump, MR.Gasket fuel pressure regulator set at 2.5 PSI, new fuel filter, Pace Setter header, 2 1/2 inch exhaust, premix.

I think that's about it as far as bolt ons etc..

You should try lowering your fuel pressure to 2 PSI. 2.5 PSI is better suited to ported engines with the Nikki.

To answer your question directly, no there is no problem running that plug at all. I got my SA with both FC leading and trailing plugs(albeit electronic dizzy) and had no issues. But as they've said to get the full benefit of the plug it needs the FC coil, which I did and am still using the FC leading while using the stock FB BR8EQ14 plugs in trailing. I also have full exhaust with emissions delete and an RB air box. My car will break the tires loose in 2nd gear, even with the 4-Speed gearing and Sumitomo HTR200's in 205/60-13's

It was hyper4mance2k that said the 2nd gen plugs can crack housings on the inside at the chrome. I personally have never seen this, but I will say that if you install them in a used engine, the compression of the existing carbon egainst the slightly longer ground electrode might lead to problems. I've noticed they can take a little effort to get tight as they get through the carbon layer.

It's probably safer to install 2nd gen plugs in a freshly rebuilt engine whose spark plugs holes are clean, or new housings.

With pretty much the same set up, I made 33mpg :)

I've run FC plugs with the stock electronic ignition and noticed no difference. They are designed for a hotter spark.

All I know is that it runs better than it ever has before. Granted I've only had the car for 2 months... The 12a is virtually identical to the 13b more or less though correct? I don't see how it would cause any problems. I cleaned away some of the carbon around the plugs holes a couple weeks ago with Seamfoam and a rag. They tighten pretty easily.

if you like them, by all means use them. they wont hurt anything :)

The reason it was running crappy before was because the plugs you were using were too cold and would foul very easily. Once you put the hotter plugs in, problem solved

ran fc leading plugs with my 12a street port with an msd setup and it ran great!

What about Fc trailing plugs?

They would be fine if you live above 55 MPH most of the drive. Just would not last as long from fouling. If your ported than it should be better to run 9s anyway.

Are you inquiring about using them in the trailing side or the leading side?

Trailing, Its more just out of curiosity

Trailing I would stick with the stock plugs.

the only spark plug that is PHYSICALLY a problem is the Rx-8 trailing ones, they are LONGER than the previous designs.

as far as power goes, i like to stick with the stock plug for the ignition system. if you want a realy upgrade the rx8 leadings are built like the racing plugs but in a "normal" heat range.

plenty of SAE papers to document which plug works better when, although in a stock setup the differences are very slight