ranger306ci

Ok, I am new to wankles, but they aren't too difficult to figure out for the most part.
But one thing is perplexing me.
Looking at the side of my 13B block, I noticed the top spark plugs have a "T" next to them , and the bottom ones have an "L" next to them. Tracing the plug wires back to the cap, the same indications are on the cap.

So, I WAS under the impression that my top plugs were leading, and the bottom ones were trailing. But the markings seem to indicate otherwise.

I thought the rotor wobbled(spins) clockwise when you are facing the front of the engine, which would lead me to believe the top plugs fire first. Am I AFU?

cdrad51

Nope, rotation it's the other way around. Leading Low, Trailing Top.

REVHED

Rotation is not the other way around! The rotor passes the top (trailing) plug first but it doesn't fire till after the bottom (leading) plug does.

cdrad51

You're right, my bad, if facing the front of the engine, with spark plugs to the right and ports to the left, the rotation is clockwise.

Jeff20B

iTrader: (13)

You can think of it like this. The compression 'dish' is longer than the distance seperating the plugs. As the rotor face comes around, the leading section of the dish gets close and personal with the leading plug first. The leading plug fires into the compression dish and as the flame front begins to travel toward the trailing edge of the dish, the trailing plug fires into the trailing section of the dish a few degrees later.

There are differences in compression 'dish' shape and spark plug locations in 12As and 13Bs. This is why timing and L/T split are a little different for each engine.

Here is a visual for you of when the plugs fire in relation to rotor position. http://www.rotaryengineillustrated.c...es/an-WCA.html

Edit: That third spark that you see right before the exhaust port opens is a late leading spark which is normal (stock) on '86-'02 RX-7s. Older rotaries with a cap and rotor ignition system do not have this. You can upgrade them though. All my vintage rotaries have it and they run noticeably better, and even sound better.