[AmuroRay]

Feeler gauge or Wire gauge?

I replaced my old NGK plugs with New NGKs (FCP Euro) when I changed my bad injector. The issue is that the current timing is terrible.

Now I when I had the plugs replaced last, it was at a shop where a bunch of work was done at the same time. There had to be less than 30k on them (likely less that 20k) And I'm not sure the shop gapped them out of the box.

My new plugs were put in with no changes - but the timing is all over the place.
Coils are basically new - Actual ELDOR S55 coils from EuroKlasse - but timing is not clean at all. I only use Costco (top tier) 93, so I'm not sure what it is.

What's the stock gap supposed to be?

Going for a drive now....

[F87source]

Originally Posted by AmuroRay

Feeler gauge or Wire gauge?

I replaced my old NGK plugs with New NGKs (FCP Euro) when I changed my bad injector. The issue is that the current timing is terrible.

Now I when I had the plugs replaced last, it was at a shop where a bunch of work was done at the same time. There had to be less than 30k on them (likely less that 20k) And I'm not sure the shop gapped them out of the box.

My new plugs were put in with no changes - but the timing is all over the place.
Coils are basically new - Actual ELDOR S55 coils from EuroKlasse - but timing is not clean at all. I only use Costco (top tier) 93, so I'm not sure what it is.

What's the stock gap supposed to be?

Going for a drive now....

I check gaps with a proper feeler gauge, I don't like those wire gauges.

If I need to gap the plugs I use a high quality gapper tool that doesn't have a sharp tip that can scratch the plug, so something like the BMS gapper tool: https://f87.bimmerpost.com/forums/sh....php?t=1754091

I go over the exact details why I prefer this tool in my review.


Stock gap iirc is like 0.032", and I prefer to stick with the stock gap and only go down when necessary.

[AmuroRay]

Originally Posted by F87source

I check gaps with a proper feeler gauge, I don't like those wire gauges.

If I need to gap the plugs I use a high quality gapper tool that doesn't have a sharp tip that can scratch the plug, so something like the BMS gapper tool: https://f87.bimmerpost.com/forums/sh....php?t=1754091

I go over the exact details why I prefer this tool in my review.


Stock gap iirc is like 0.032", and I prefer to stick with the stock gap and only go down when necessary.

I'm going to check my old ones today after work - I'll then figure out what my new ones are at. Hoping it' just the winter gas, but I don't know. My timing was pretty clean before, I should have left it alone.

[AmuroRay]

Never even got to the garage. My child had a fever and I was taking care of her all night. I went from driving 30K a year (one of the reasons I opted for the M235i over the M2 - the other was cost) to driving to church on Saturday once a week - maybe. Everything is done through my wife's car, so my car basically just sits until I can find an excuse to drive it.

Hopefully I have time to tinker tonight, still want to grab a gauge and measure the old spark plugs before I return them to FCP.

[samsamdar]

I remember seeing somewhere that stock gap is actually around 0.028", which is smaller than what is claimed. I've been running 0.020" NGK 97506 and Eldor coils for 2 years now with no issues on ACN91 or E85...

[AmuroRay]

Originally Posted by samsamdar

I remember seeing somewhere that stock gap is actually around 0.028", which is smaller than what is claimed. I've been running 0.020" NGK 97506 and Eldor coils for 2 years now with no issues on ACN91 or E85...

Are you running the S55 version (which Is NOT available on FCP) - Any issue with them failing prematurely?

I'll see if I can dig up anything on the plug gap...

[samsamdar]

My b - I am running the Eldor 12135A06753 from FCP euro. No issues so far and I’m on my third set

[ggggbmw]

Found this video from NGK on recommended gapping methods:

They recommend staying away from coin style tools, and seeing how they demonstrate the (mis)use of that tool to set a gap, I can see why. However, I like to use the coin style, VERY GENTLY, just to check the gap of plugs. I find that the ramp gives a better fit than a lot of wire type gauges and you can get an exact measurement that falls between wire sizes. I then use a wire type tool with the little hooks to bend the ground electrode to fit. Again, gently, and lots of little tweaks are better than one push.

[AmuroRay]

Originally Posted by ggggbmw

Found this video from NGK on recommended gapping methods:

They recommend staying away from coin style tools, and seeing how they demonstrate the (mis)use of that tool to set a gap, I can see why. However, I like to use the coin style, VERY GENTLY, just to check the gap of plugs. I find that the ramp gives a better fit than a lot of wire type gauges and you can get an exact measurement that falls between wire sizes. I then use a wire type tool with the little hooks to bend the ground electrode to fit. Again, gently, and lots of little tweaks are better than one push.

I bought two tools, one wire and one that looks like a swiss army knife - I measured out the old plugs and there were all .028-.030

[F87source]

Personally I recommend feeler gauges and the bms gapping tool. The wire probe isn't the best imo, and tapping to close the gap isn't ideal.

[ggggbmw]

The BMS tool looks nice, but it only lets you close the gap. You would still have to use another tool to open the gap. Like prongs on a wire gap tool, or a small pliers like the BMS video suggests. And backing the plug in and out of the BMS tool to open it would be tedious.

And even though I am huge tool snob/accumulator, I also find that the older I get, the less tolerance I have for spending money on expensive rarely used tools because "I'll have them the rest of my life".

[F87source]

Originally Posted by ggggbmw

The BMS tool looks nice, but it only lets you close the gap. You would still have to use another tool to open the gap. Like prongs on a wire gap tool, or a small pliers like the BMS video suggests. And backing the plug in and out of the BMS tool to open it would be tedious.

And even though I am huge tool snob/accumulator, I also find that the older I get, the less tolerance I have for spending money on expensive rarely used tools because "I'll have them the rest of my life".

To check gap use feeler gauges. Those wire tools suck.

Ideally with the proper gapping procedure you will never have to open up the gap. Start big go down only if needed, and plugs are prepped to bmw specs so you will never have to go larger than that.

[ggggbmw]

Really? I find that I'm more likely to have to open the gap than close it. Especially historically when plugs were less well packaged and they would bounce on the ground electrode inside the box.

The last time I did plugs on an N55, with brand new BMW plugs bought at the dealer, 3 were spot on, 2 I had to close, and I had to open 1. None were far off, and a time-sensitive mechanic would have slapped them in and it would have been good enough. But I take great care when doing my own work, and I like to be as perfect as I can.

And yes feeler gauges are nice, and I do own some, but I find them a bit more effort to use. The key thing though, no matter what you measure with, is to be GENTLE, and not scratch, chip, bend, or break the center electrode, or the surface of the ground electrode near the gap. If you're careful, you can measure with anything.

[F87source]

Originally Posted by ggggbmw

Really? I find that I'm more likely to have to open the gap than close it. Especially historically when plugs were less well packaged and they would bounce on the ground electrode inside the box.

The last time I did plugs on an N55, with brand new BMW plugs bought at the dealer, 3 were spot on, 2 I had to close, and I had to open 1. None were far off, and a time-sensitive mechanic would have slapped them in and it would have been good enough. But I take great care when doing my own work, and I like to be as perfect as I can.

And yes feeler gauges are nice, and I do own some, but I find them a bit more effort to use. The key thing though, no matter what you measure with, is to be GENTLE, and not scratch, chip, bend, or break the center electrode, or the surface of the ground electrode near the gap. If you're careful, you can measure with anything.

Yeah, I was lucky enough that I have only ever had to gap down. The plugs I buy have a pretty good cardboard tube that surrounds the tip of the plug, and that protects it very well.

[3t3p]

Neither, throw them in from out the box lol
Unless they're doing it for me..which I don't know. Doubt it. Anyway car runs great!

[Track/S]

The best tools to gauge the spark plugs are these, BMS tool twist the electrode.

[F87source]

Originally Posted by Track/S

The best tools to gauge the spark plugs are these, BMS tool twist the electrode.

Yeah those tools are also really nice, I just don't like where they put the force on the plugs - which is where the ceramic body meets the metal hex area. Where's the bms tool puts any and all forces on the threads which is where they're meant to be. Either way it shouldn't be an issue since the forces at play are very little.


In terms of the bms tool testing the electrode, I don't think thats a concern since the contact latch between the plug and the tool is so small there's not enough friction to cause it to twist. I've gapped all of my old spark plugs just for fun and none of them had issues. The bms tool also puts the force on the very tip of the electrode so it doesn't put any force near the spine of the electrode and the bend radius is smooth.


But my favorite part of the bms tool is since the plug threads into it, it can't fall out so I can bring it up to my eye for a closer look without having to hold the plug in place.


Either way both tools should be fine.

[Track/S]

Originally Posted by F87source

Yeah those tools are also really nice, I just don't like where they put the force on the plugs - which is where the ceramic body meets the metal hex area. Where's the bms tool puts any and all forces on the threads which is where they're meant to be. Either way it shouldn't be an issue since the forces at play are very little.


In terms of the bms tool testing the electrode, I don't think thats a concern since the contact latch between the plug and the tool is so small there's not enough friction to cause it to twist. I've gapped all of my old spark plugs just for fun and none of them had issues. The bms tool also puts the force on the very tip of the electrode so it doesn't put any force near the spine of the electrode and the bend radius is smooth.


But my favorite part of the bms tool is since the plug threads into it, it can't fall out so I can bring it up to my eye for a closer look without having to hold the plug in place.


Either way both tools should be fine.

It is the same to exert force on the thread or in the hex area, it will not do any damage, the BMS tool when applying force by screwing it twists the electrode in the direction of tightening

[F87source]

Originally Posted by Track/S

It is the same to exert force on the thread or in the hex area, it will not do any damage, the BMS tool when applying force by screwing it twists the electrode in the direction of tightening

Ok great it's not touching the ceramic body, that's really good to know.


So the thing is for the BMS tool to twist the electrode it must be able to have enough friction against the electrode itself to exert a torque to it. But since the surface area between the contact is so small, and since friction force is defined as coefficent of friction X normal force - we can't actually exert much normal force since the electrode deforms as it flexes down so friction force itself isn't going to be very high either. So the combination of a really small surface area and low amount of friction means you can't exert a high enough torque to twist the electrode. Atleast in theory you can't, and I've never seen this style of tool actually twist the electrode before. Also since you can thread the spark plug deeper into the tool just by holding and twisting it from the electrode, the spark plug would rotate within the tool long before the electrode would be twisted and warped. So it shouldn't ever happen.


On a side note I actually have that exact same tool in your photo on the right, and those screws are really sharp and it made marks on my spark plug electrode while screwing them down. This is why I got the BMS tool, because the bolt on the bms tool is smooth and doesn't damage the electrode.



Overall im actually liking that tool you showed, it seems like a really really good option since it only exerts a force down on the top of the electrode and there is no additional rubbing. However, the reason why I prefer the BMS tool is because it allows me to pick up the tool for a closer visual inspection and reposition it sideways or whatnot without having to hold the spark plug into the tool or worrying about it falling out. But it's just personal preference at that point.