94sc400boi

So i have a question about the spark plugs, does anyone know the correct measurements of the plug arches so ik its not heating up to fast id like to keep the plugs as long as possible if anyone can help that would be great my direct snap is hmuhunterlacey you can message me there or on here, thanks very much

CLass of 1

Are you asking about the spark plug gap? The recommended iridium plugs come gapped properly and do not need to be adjusted at all. Just drop them in. Denso SK20R11 is what I used for my recent tuneup. That is the factory recommended plug for the V8.

Hope this helps.

Nick

94sc400boi

Yes this was helpful thank you very much

RXRodger

iTrader: (2)

So to the original poster this above is not necessarily the case. Always check your spark plug gap. There are no exceptions to this advice. You can not know that it was set correctly, or maybe got dropped in shipping, or any number of reasons the gap may not be set correctly. Google “spark plug gap Lexus sc400” and you should see 0.044”.

CLass of 1

Very few people have the means to check their gaps. They come gapped at 0.044. You should also check your tire pressure before every journey and probably re-torque your lug nuts every month. I think it’s an acceptable practice to install a plug which is pre-gapped without checking. If you’re building a race car, a slightly altered gap could mean all the difference. He won’t notice it going to Best Buy.

Nick

RXRodger

iTrader: (2)

The parts stores used to offer these free at the counter but probably have to buy it now. Or you can use a feeler gauge. It takes 10 seconds to check before you screw the plug into the head. Plugs typically last 100,000 miles and is a pretty involved job on these cars. There is no need to skip this step. And yes, I have pulled plugs out of the box and the gap set incorrectly. It happens. Check the gap before you install. No exceptions.

94sc400boi

Thx i will check them just in case

SC400slide

iTrader: (11)

I will have to echo the aforementioned-it is a good practice to double check the pre-gapped spark plugs. I just put some in my SC300 and a few of them weren't even close. Probably bounced around in shipment or were dropped

RXRodger

iTrader: (2)

Yeah the one thing worse than getting no advice when you ask for it is to get bad advice. If you don’t know or you aren’t sure you should refrain from giving advice.

SC400slide

iTrader: (11)

ummm...just was seconding what you said because it has proved to be true in my experience, do you see that as bad advice?

CLass of 1

No he’s talking **** about my advice.

I stand by it though. Drop the damn plugs in. People are often afraid to do the work themselves because of all the barriers. The likelihood of a plug which is pre-gapped, not being correct is very low. It happened to you, cool. I’ve done plugs on my cars three times. A 4 banger, a 6 and an 8 cylinder. So that’s 18 spark plugs across three cars, no issues whatsoever. I just don’t think you need to be paranoid about double checking Denso’s work. Do you check resistance of your plug wires before installing too? Leak test your oil filters? Give me a break.

I’m relatively new even though I’ve been a member for more than a decade. I try to stay in my lane. I ignored the comment, to this point. I don’t ever mind a differing opinion to my own, but suggesting I shut up and don’t give my opinion is beyond the pail for me. I won’t be censured by some self-righteous online arbiter of sound advice.

Respectfully,

Nick

Frankn

I agree you should double check the spark plug gap even if they come pre gapped. The chances are low but ive seen cars with a rough idle caused by trusting the pre gap that was hell to diagnose

RXRodger

iTrader: (2)

Sorry not intended for you, should have made that clear. I was intending to add to or back up what you were saying.

1997Soarer

iTrader: (1)

There was a post similar to this on FB, and it brought to light that a lot of the higher end spark plugs are being counterfeited, and those counterfeit plugs are being sold on Ebay, Amazon, and have even made their way to RockAuto.
So it's a good idea nowadays to inspect your spark plugs and compare them to the warnings found on the NGK and Denso websites. The counterfeits are getting really good, but as long as you know what you are looking for, you can still save yourself some serious headaches.
Even Denso suggests that if your plugs look suspicious, you need to measure the gap.

sajack

So, is everyone going to continue to replace spark plugs at 40,000 mile intervals in order to maintain emissions system warranty? That’s what Lexus says it’s for.
Pretty sure plugs on the V35 engine could go much longer like other modern day engines.
This seemed like $500 wasted. My car ran perfect before and after installing new plugs. The old plugs look just fine, like they most likely could go another 40,000 miles.
Guess we can change brake fluid and differential grease at 60,000 miles too.