Ive had my iridiums for a while now and im wondering if plugs can cause knock? Had a few higher RPM misfires lately. See around 3-5* KR.

Also told winter gas can make this happen too?

Tuned for 14* on my 2.8 pulley car on 93 oct.

 

I think plugs can cause knock if they aren't cold enough plugs but their material shouldn't make a difference. Winter gas probably has a lot to do with it because it's not as high quality and probably has some additives that make it behave like a lower octane

 

I have 1 step colder than stock (NGK 6509). Last tank i saw 3-5* and this tank i mixed E85 and only seen .5* so far.

I do get some higher RPM misfires sometimes (sounds sweet...haha)

 

Gap on the plugs may be a little too big and you're getting spark blowout. Don't mix in much e85 or you'll be running to lean and have more issues. Why not get tuned for e if its around you?

 

No money for injectors.

I never go above 12.5 AFR when i mix.

I just use stock gap for my plugs

 

Try like .034, seems to be a good gap for most people but really you just have to play with it to find the sweet spot

 

How do you gap iridiums?

 

I keep my gap at .028.How much boost are you seeing?

 

Oh and you can run a 50/50 blend of E85 with 60's. I have a tune waiting to be loaded for 50/50 and I have 60's.They just can't support full E

 

If adding E took the KR away then its the winter fuel causing it. I would lower the timing a bit and tighten the gap to see if the misfires go away.

 

Mine are gapped at .32 and .28 depending on wut tune its on

 

i dont think you can gap iridium?

 

14 lbs in higher RPMs

Thats what i thought

 

Could be valve float if it's missing at all on the top end.Our valvesprings tend to float around 13psi or higher.And you can gam iridium.you just have to be gentle.your more than likely going to be pushing the gap smaller.I gap mine @ .028 with no issues.I also run 30% E85 at the moment too.

 

Why does everyone think you can't gap iridiums? Just don't use one of the tapered gauges and you'll be fine. Doing it that way could break the tip off the electrode but if you get one of the tools like this below you'll be fine.

 

Exactly^^.Anytime I have changed my iridiums out.I usually have to push the gap down in which I just put the ground electrode on the ground and give it a little push until it's where I need it to be.

 

And if someone is really that worried about it, just get a set of coppers (3672)

 

How could PSI cause valve float?

I think stock on these plugs is .040

 

Because PSI is positive pressure right???Positive pressure being forced through the valves thus causing them to float(almost like a umbrella effect).Feel free to ask tundraboarder666 how he feels on this subject.13 psi on his setup and they floated bad when you went over 5k.Popped in the ZZP 82#ers and no mas float.Not saying that's what it is but it's a possibility.

 

^That exactly. I wouldn't say it's really common but I think quite a few boosted people have had valve float. Which is odd considering all cobalt valve springs are the same but the LSJ never seems to have float when supercharged on stock springs. Regardless they need changed, at least for us, before running higher boost

 

I not sure why either.Only thing I can think is the LSJ has less lift then we do,but I am not positive that is why we float and they don't.

 

That's shitty. I want to do 2.7 in the spring. :/

 

I think that will cause issues other than valve float lol

 

Dont say that!

 

I wish you luck with that endeavor I'm just saying