First off... 79 12a, 118,000 miles, 2gdfis, Blaster 2 trailing coil All tune up parts are new. Royal Purple 20-50, Sterling Nikki with 0.43 SAE primaries, and stock 160 secondaries.Timing set at 0* 20* with vac advance plugged into 2nd from the bottom left of carb base. New stock fuel pump with no regulator.

Question...
Racing Beat recommends BR7EIX spark plugs for leading and trailing. I bought a set and they seemed great the first time I started it up. I noticed shortly afterwords that giving it light throttle from a stop will cause it to sputter. Also if you rev it hard and let the clutch out to drop it to idle speed it will either bog to 300RPM or it will just die all together.

I pulle the plugs after I put 300 miles on them and they are clean as a whistle. Barely any carbon! So why the bogging? I switched back to BUR7EQPs on Leading and kept the BR7EIX on trailing and it seems to run great again! So why does RB recommend these plugs on leading? Is there something I should retune when using them to eliminate the sputters?

 

When I ran those plugs I found they liked a lot of advance. I set my timming at 20* of advance per Paul Yaw's instructions. http://www.yawpower.com/pultime.html Being a 7 heat range those plugs are very unlikely to foul, but I highly recomend a CDI box to help keep them clean. The tiny electrode makes them more likely to foul in a very rich(rotary) situation, Make sure you have to power to keep them firing.

 

I noticed that when I upped my advance it seemed smoother, but I didn't want to burn anything up by going too far so I just bumped it up a few degrees. I like the way it feels with the BUR7EQP Leading and BR7EIX trailing.

 

On another note. i have tried all the fancy plugs out there, but my car has never ran batter than it does with stock Rx-8 plugs...

 

So with my setup the RX8 plugs should work fine with no extra modifications?

 

They should. I run the stock Rx8 leading and BR9EIX in the trailing. I actually even run the Rx-8 plugs without the crush washer on them to bump compression up .000001 of a point. LOL! I do run a really trick Ignition setup though. I pulled my plugs the other day after 7,000 miles or so and they are still in near perfect shape.

 

I run the BR7EIX plugs in my REPU, absolutely fantastic plug! Starting, throttle response, idle, acceleration, all greatly improved over the BR8EQ14's I had in there. It's a fantastic plug.

Never tried Rx8 plugs, on the to-do list.

For your situation, perhaps a leading plug wire came loose or water got in there.

 

ive tried the rx8 plugs in everything, and in the gsl-se they were great, peepers seems to like em.

BUT

the FC does not, i put the rx8 plugs in, and it didnt run so hot, it wanted a bunch of fuel pulled out everywhere (i have an AFC)

SO

id reset the idle mixture, maybe play with timing too

 

I got a **** load of BR8EIX BR7EIX and BR9EIX from G.I. Joes for $2 a plug when they were going out of business WIN!