I just bought a 1986 n/a Rx-7 from a friend. He told me that the 13B was just rebuilt about a month ago but will not start. I looked at the spark plugs and all had the T (trailing) on them.Do I need the leading spark plug to make the car run or does it matter? I asked him about it and he said that he pulled them from his 89 Rx-7 turbo and that it worked fine with his car. iwould just buy the (L) sparkplug but it will cost $34.99 each (special order). Any help will be great.

 

You need to get some NA plugs, there turbo plugs are different. And get two trailing and two leading. The trailings go in the top, and the leading ones go in the bottom.

 

Complete and utter bullshit.
The stock TII plugs are the exact same as the stock NA plugs. All are NGK
Leading: BUR7EQ
Trailing: BUR9EQ

Sometimes people put the trailing plugs in at all four corners when driving hard. It is a more common practice on the turbo cars.

Putting in the stock leading plugs will not likely make any noticable difference to the cars performance or drivability.
The stock spark plugs, from mazda, are around $7 each. Its never a bad idea to replace them.

 

auto zone had them for 5.50 a peice, ngk's

 

advance auto @ $6.00

 

I have the leadings for only $4.50 on my webstore