Leading and trailing just specifies the possition of the plugs not the type... is this correct?

 

no there is a difference in heat range. the trailing plug is a hotter plug used for emission reasons. you can run all leading if you wish. they are colder.

 

What are some good plugs to get?

 

Do the plugs fire at the same time? Does the leading and trailing plugs fire in the same combustion process?

 

From what I've read on this forum and the various RX-7 sites I've come across... NGK plugs are the way to go. They're the same kind as what comes stock, so you can't go wrong with those.

On a related note, has anyone tried the new DENSO Iridium plugs? How well do they work with a rotary??

 

The only thing I can find in the manual about the timing sequence is that the leading is 5 deg. ATDC and the trailing is 20 deg. ATDC.

 

One thing of interest . . . the leading plug is the lower plug and the rotor spins by the upper plug (trailing) first and then by the leading plug . . . . just to make your head hurt. That timing split of 15 degrees (between leading and trailing) is typical. Some people don't keep this split. They claim more power, however others claim that the engine is less reliable . . . I claim make your own guess!

 

An easy way to remember which position is trailing is that it is the top plug in the rotor housing. Trailing is Top.

Also, the leading plugs are actually hotter, so it is common for people to run all trailing plugs, because they are colder. The leading plugs are 7s and the trailing are 9s, racing plugs come in 10, 11, 13 but they are not good for the street for most cars. If you have a "hotter" car, you want to run "colder" plugs.

The two leading plugs (one for each rotor) fire at the same time, twice as often as each trailing plug. I know that is confusing, but it just means that both leading plugs are fired each time either rotor needs a spark. The trailing plugs are positioned such that they cannot be fired at the same time, so the trailing plug for each rotor gets its own coil and is fired individually. This is also part of the reason that the leading plugs wear out faster than the trailing plugs -- they fire twice as often.

-Max

 

what are the benefits of having the plugs fire cooler...besides reducing detonation?? Are there any loss in performance by using a cold plug ie. all 9's??

 

The dealer told me not to wash the engine bay because it will mess up the spark plug wires... should I put on the hip waders or is this an actual concern. The other question I have for you RX savvy people, is it normal to find a black oily substance throughout the air intake, air box, and all the air plumbing.

There's a sputter durring accelleration, hope a change of plugs and wires will fix it.

Newly aquired 94

The only mod I have is an RP Radiator.

Thanks,

Craig

 

Where is a good place to get the NGK plugs? Would any autoparts store have the ones I need for my FD?

 

The dealer is on crack. Wash the engine bay.
The oil is normal, unless it's excessive.
when does the hesitation occur?
3K is normal, and you'll feel the hiccup from the turbo transistion at about 5K.

 

you can get NGK plugs at any auto part store that caters to imports. I even got a set at NAPA.

 

My R1 eats 'em up....on the stock motor, I'd go through platinum NGK 9's in 8-10k miles. They'd come out looking like absolute ****, too.

Re: places to buy them, check all the parts stores around you. I found them at an advance auto parts for like 6 bucks each.

 

The heat range of a plug does not affect the ability of the ignition to fire, or directly affect the spark. Is has to do with the operational temperature of the center electrode. For a single spark plug type and design, what varies for the differnent heat ranges, is the thickness and length of the ceramic insulator around the center electrode. A hotter plug will cause the center
electrode and insulator to operate at a hotter temperature.
This helps to burn off deposits and keep it cleaner thus insuring a good spark. If too cold of a plug is used, especially with a dirty running engine, deposits will build up on the plug tip and make it
harder for the spark to jump the gap. If too hot a plug is used,
pre-ignition can occur due to residue heat in the plug. That is why
engine running high boost run colder plugs.

In reality, you can run a cold as posible plug as long as the tip
burns clean of deposits. With my PFC, BUR9s run as clean as
BUR7s did with the stock ecu for the leading plug in city driving.

 

Thanks for the response,

Sometimes I feel that I'm the only one person in the area with an RX 7, finding parts for these things is hard. You would think the dealer would have plugs and wires in stock but no.... you have to order them. Not to mention the price... oh well. It's well worth it. Just smoked a 90's Camaro, he must have had a 305, stock, grey primered, hugh hood. I guess he's getting ready to put more hamsters under it.

Next on the list,
Down Pipe

Thanks

Craig

 

Probably more Fds in your area then mine. Down here in wichita i've only seen maybe 3-5

 

So is the leading plug colder? or the trailing pluG? and has anyone ran just the colder plug instead of leading and trailing? Cause a lot of people are spending $30-$40 on racing plugs w/are 10.5's or even higher. But if I can run 9's all the way around that seem alot more economical.

 

The deal with running colder plugs is this in my opinion. If you have a good amount of mods, run your car hard or live in a warm place then the colder trailing plugs with heat range 9 is probably best for all 4 plugs. If you put around town, have a mostly stock car or live in a cold place go with the stock 7s leading and 9s trailing. Never put the 7s in the trailing position! For more info on plugs you guys might be interested in my plug research for the 3rd gen. It's on my web site.

 

The only other FD that I know of is still setting on the show room floor. Black, automatic that doesn't run very well.

Zoomspeed, do you go the SCCA Solo races?

Craig.

 

We have solo races around here? I don't know to much about the race scene around here yet. Where are they at?

 

SCCA of Kansas' web site.

They cover most of the KS, KC/MO areas. Check out their schedule.