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Spark plug for our L36?!

S

slimguns

New member
Hello guys, when I got the car (before I found this site) I did a tune up that included plugs. I bought the hottest iradium triple headed blah blah blah the guy said would work. Well, now that I have half an idea of what I'm doing I have starting scanning and noticing knock. Basically, since I'll be installing headers this weekend I want to replace my plugs with either just stock or even one range cooler. Reason being I live in New Mexico and I have hot thin air.

The question, has anyone tried the autolite xp605 vs the normal 605. Autolite says they are the same heat range but with more durability. Any ideas?

TIA,
Slim
 


Those are stock replacements. Unless your seriously modded in your na car you dont need to run colder plugs.
Sorry didn't notice that those plugs weren't platimums.
 
But yeah if your car is stock run the XP606s, all your gonna do with the 605s is kill your gas mileage. I don't remember who it was that said it but you want to run the hottest plug you can not the coldest.
 


The waste spark ignition system eats the platinum plugs.

Copper core and the factory Iridium plugs are the best for the car.

But for you being a NA motor, the AC delco plugs are the best.

The KR you are seeing is just a normal thing for a stock car to see, you can try running a 91 or 93 octane fuel to lower it some but likely a little kr will still be there.
 
What do you mean knock? Like your car is literally knocking or you are scanning and seeing knock retard? And I don't remember the specifics but the ignition system doesn't play well with platinum plugs.
 
The only mods are alt/fuse box rewire, fuel pump rewire, oversized radiator, 180* thermostat, under drive alt and water pump pulley, zzp headers, tog catless dp, and a slightly modded tune (I'm just learning).

Im pretty sure I put plats in now that I'm thinking about it. :-(
 
Just for some insight, I believe I read it in a post by Bill, the waste spark system (firing two plugs off of each coil pack) causes one plug to fire normally, and one to fire with reverse polarity. That causes platinum conductors to actually arc and transfer to the "prong" on the plug, quickly enlarging the gap to the point of misfire.

I run copper personally, but only because I like to peek at the plugs every other oil change to see if anything it amiss, so I may as well put new ones in while I'm down there.
 


I'm scanning and finding roughly 1-2* KR during shifts. The big numbers come in at 50%+ throttle position in 2nd and 3rd gear around 2500-4500. I'm getting 5-9* but I let off before I see how far it goes.
 
Why did you put headers on a stock n/a car? Idk what normal kr is for a l36 but with headers I dont think it should be that high, I would look at your motor mounts to make sure your not getting any false knock.
 
Oh I missed that in the original post. But I'll ask again why are you running headers on a n/a car and ZZP headers at that? You have no mods and are n/a, your not even in ported manifold territory. I think a cam or hv3 would have been a much better investment.
 
I'm installing a top swap soon and I'm putting on the supports first. I'm hoping the headers help clear that up a little. I wasn't getting these KR numbers (as far as i know) just a few weeks ago when we had cooler temps. I'll move back to the stock plugs and update once my fuel trims settle again with the headers.

Thanks again guys.
 


If you have a bigger aftermarket sway bar on the front, make sure you install it upside down or it will bump the headers and give you false KR.
 
If he's top swapping, would it be easier to leave the headers in the box and install them with the new heads?

Also was the "tripple headed" comment about your plugs scarstic or did you get like the E3 plugs or split fires (whatever has multiple tips)? If so could this cause issues? I know on the LS motors it drives the ignition system crazy...
 
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