I was on another forum, and someone posted that they like to use trailing plugs all around instead of 2 leading, and 2 trailing.

..something about the trailing plugs burning hotter...anybody know about this?

 

I thought it was the other way around and that the Trailing ran at colder heat ranges, which would be better for a more performance oriented engine as opposed to normal street driving.

 

i think they meant to run 9's on both trailing and leading

 

If the trailings are 9's and the leadings are 7's how do you get leadings in 9's?

L=BUR7EQ
T=BUR9EQ

 

just buy 4 trailings if you want 4 9's

 

9s are more resistant to heat soaking, but they dont reach operating temperature (cleaning temps) as fast as the 7s will. Lots of us run them for added knock protection.

 

Thanks J-Rat.

 

Is there any reason to do this in an NA engine? My engine builder told me to run 9's all the way around since it wa a pretty heavy street port.

 

Porting has nothing to do with what heat range spark plugs to run.
It's a matter of how well the spark plugs are doing under normal use.

Colder spark plugs *might* allow the engine to run a bit cleaner at the top of the RPM range, if you're having ignition break-up issues.
As a rule, most non-turbos do not need to do this.

If you're running a CDI box (on the leadings), it's highly recommended to run 9's in the leadings for better spark plug life.


-Ted

 

all I have to say is to get the irridium plugs. I got the non irridium ngks and mine backfires all the time and pops alot while it is warming up. It just isnt burning the gas off good enough. Also, colder heat range plugs are usually used while running nitrous on a car.

 

2 leading, and 2 trailing?? i remember when i buy spark pulgs that guy ask me if i want these..and i said ok.....and i didn't even remember when i install them......does it matter?

 

Yes it matters. If you are using NGK rotary engine plugs, they are marked L for leading or lower, and T for trailing or Top/ upper.

Using the wrong temp plug in the wrong location can result in cold weather fouling and flooding as well as warm weather pre-ignition/detonation/knocking.

 

Nice 1st post. Welcome to the club!

 

so..don't matter front/rear....so the one marked L go's at botten..and marked with T go on top right? no wonder ..........my car wont' start if i just turn it on for few sec and shut it off....after that....it will be hard to start...

 

that is a classic sign of a failing motor and low compression

 

dag....great first post come out to the shop already we can get all ur wirings settled