Gapping spark plugs. Metric gapping tool?

[Tegger]

Originally Posted By: Tegger
I'd be surprised if Bosch didn't advise against that much reduction...

Update: I just checked. They don't seem to mention a maximum reduction (unlike NGK), but... they say it's OK to tap the plug against a surface to reduce the gap!
http://www.boschautoparts.com/BAP_Technical_Resources/Spark Plugs/SparkPlugGapping.pdf
Not that I'd ever want to do that, myself.

I use my Kastar plug-gapping tool for everything. It's an older one, with swing-out fingers like a feeler gauge set. Each finger has three loops of wire. Each loop has a different diameter. I have loops from .025" to .050".

I see Kastar now sells something called an "EZ-Grip".
Go to http://www.google.com , and search for these terms: kastar spark plug gapping

 

[antiqueshell]

More great detailed info Tegger! Keep it coming!

I have a question though. I mentioned that the OEM gap for my
ABA 2L engine on my VW Golf is actually like I stated above
0.7mm (0.028in) the plugs listed by Bosch (which no doubt are able to satisfy multiple applications) have a gap from Bosch at
1.1mm or 0.043in. Are you saying that the OEM gap is in error?

 

[Tegger]

Originally Posted By: antiqueshell
I mentioned that the OEM gap for my
ABA 2L engine on my VW Golf is actually like I stated above
0.7mm (0.028in) the plugs listed by Bosch (which no doubt are able to satisfy multiple applications) have a gap from Bosch at
1.1mm or 0.043in. Are you saying that the OEM gap is in error?

I have no idea. But 0.7mm seems kind of tiny by today's standards.

Check your underhood EPA sticker; that's normally the last word on tuneup specs. Is that where you're finding the 0.7mm spec?

 

[antiqueshell]

@Tegger:

Unfortunately my year and other year VW have no stated spark plug gap listed on that EPA sticker which BTW is not on the hood but placed on the panel next to the hood latch striker. LOL

Here is what Bosch lists as the OE silver plug which did in fact come with my car originally.

0 242 229 597 - Spark plug, Silver
Current product Comparing product
Description Spark plug, Silver -
Vehicle manufacturer service (OES) 0 242 229 597 -
Designation Spark plug, Silver -
Production discontinuation - -
Type formula FR 8 DS -
Electrode gap 0,70 mm -
Thread diameter M 14 mm -
Thread length 19,0 mm -
Thread pitch 1,25 mm -
Width across flats 16,0 mm

One thing most German product sites never lack is technical data!

 

[yonyon]

Back in the days of my youth, when I was even more foolish than I am now, I bought a replacement EPA sticker because the one on the car was a bit faded. I waited two weeks for it to come in, and was oh so happy when I finally got to pick it up and stick it on! It was just under a year later that I got the recall notice in the mail advising me to bring the car in for an emissions recall. The original EPA sticker showed the wrong spark gap. They would, at no cost to me, replace my EPA sticker with an updated sticker with the correct spark gap printed on it. It turns out that the sticker I just paid $21 for was the new updated sticker that I would have gotten for free had I waited. Thanks, Cadillac!

/just sayin

 

[mgm13]

I also use the Kestar tool for plugs, I have closed the gap on new plugs for the last 50 years by tapping on a 2X4 until proper gap was obtained. It seems not uncommon for the MFG to have a larger than required gap. About the .028" check VW spec, I don;t know if yours is a turbo model or not but it is often necessary to close gap on turbo aps because too much gap can let the spark be blown out at high boost.

 

[Tegger]

Originally Posted By: mgm13
it is often necessary to close gap on turbo aps because too much gap can let the spark be blown out at high boost.

Oho! Not being a vee-dub guy (or even a turbo guy), I never thought of that. This makes sense to my old and creaky mind.

I may be old and creaky at the advanced age of 50, but I have no experience with VWs or turbos. Well, I did ride regularly in an early-'60s Bug owned by my best friend's mother, but that was 40 years ago...

 

[antiqueshell]

@Tegger:

Just to let you know this is a very ORDINARY 2.0 occasionally you'll hear the ABA engine referred to "lovingly" as 2.SLOW on any VW waterpumper forums. There is no turbo or anything special just a normally aspirated lump, really its origins stretch back to the mid 70s where it was a 1.5L in the MK I Rabbit when it debuted. I think the only real updates are the hydraulic valves (which I wish they weren't because manually adjusted valves are less trouble prone if maintained with occasional adjustments). LOL On the plus side it is indestructible and completely reliable.

 

[mechtech2]

Originally Posted By: Tegger

That .7mm gap is small, for a modern car - really small. Maybe it is for a special stock dual electrode type plug,?

I was wondering that myself. Don't you usually find the dual-electrode type on "wasted spark" systems? [/quote

No. Single elactrodes work better for waste spark systems.
And all spark plug gappers do NOT have adjusters on them.. Of course, SOME do.

As to a spark being 'blown out', that is nonsense. Once fired, the large gap is better to help insure a burn. But with higher pressures, it takes more voltage to fire across the gap. But it is NOT blown out.

I tap all the time to close a gap - Why not? i think it's better than leaving a scratch from a tool to possibly incite pre ignition.

 

[Tegger]

Originally Posted By: mechtech2
Single elactrodes work better for waste spark systems.

Somebody forgot to tell Toyota. Our Tercel has a wasted-spark system with dual-electrode plugs.

Apparently the reasoning is that double the metal compensates for double the sparks. Makes sense to me.

 

[antiqueshell]

Originally Posted By: Tegger


By the way, some spark plug manufacturers do not recommend changing the gap beyond a certain amount. You want to close yours by .044", which I think you may find to be outside the allowable spec.


Tegger tell me more about this?

Although I don't see any advisory about not closing the gap more than a certain degree. I know that an alternate gap for my car is .8mm or .032in do you think this would be more reasonable for the plug?

 

[yonyon]

This prohibition about excessive closing of the gap, I believe it is specific to single J-shaped ground electrode type spark plugs. You can get too much overhang effectively shrouding the spark; this would be doubly undesirable if you were planning to go so far as clocking (indexing) the plug. A very fine needle file can correct this issue.

Even worse, if you aren't paying attention to the shape of the J, you may bend too much where the electrode branches off from the threaded area and the actual gap (shortest gap) can move to the wrong part of the electrode. This gives you a shorter gap than you're measuring and more importantly moves the spark back as though you were using a plug with less protrusion. A good pair of pliers that you're VERY familiar with can make a better tool than any purpose built gap tool for avoiding this problem. I still use a small hammer to keep a good J and avoid bending back and forth if it's an unfamiliar brand plug.

 

[Tegger]

Originally Posted By: antiqueshell
Originally Posted By: Tegger

By the way, some spark plug manufacturers do not recommend changing the gap beyond a certain amount. You want to close yours by .044", which I think you may find to be outside the allowable spec.

Tegger tell me more about this? Although I don't see any advisory about not closing the gap more than a certain degree.

Bosch doesn't seem to have such a warning, but NGK does.
http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqgap.asp?mode=nml


Originally Posted By: antiqueshell
I know that an alternate gap for my car is .8mm or .032in do you think this would be more reasonable for the plug?

I have NO idea. Only VW knows how they designed your engine, and only VW knows what the proper gap is.

VW probably put a plug-gap specification in your Owner's Manual...

 

[antiqueshell]

Originally Posted By: yonyon
This prohibition about excessive closing of the gap, I believe it is specific to single J-shaped ground electrode type spark plugs. You can get too much overhang effectively shrouding the spark; this would be doubly undesirable if you were planning to go so far as clocking (indexing) the plug. A very fine needle file can correct this issue.

Even worse, if you aren't paying attention to the shape of the J, you may bend too much where the electrode branches off from the threaded area and the actual gap (shortest gap) can move to the wrong part of the electrode. This gives you a shorter gap than you're measuring and more importantly moves the spark back as though you were using a plug with less protrusion. A good pair of pliers that you're VERY familiar with can make a better tool than any purpose built gap tool for avoiding this problem. I still use a small hammer to keep a good J and avoid bending back and forth if it's an unfamiliar brand plug.


yon yon..thanks...I love detailed technical information and it appears that what you and Tegger have posted is not easy infomation to come by at least on the net. Interesting read. I will follow your recommendations to keep the side electrode as close to the original shape as possible, while closing the gap.

 

[antiqueshell]

Originally Posted By: Tegger
Originally Posted By: antiqueshell
Originally Posted By: Tegger

By the way, some spark plug manufacturers do not recommend changing the gap beyond a certain amount. You want to close yours by .044", which I think you may find to be outside the allowable spec.

Tegger tell me more about this? Although I don't see any advisory about not closing the gap more than a certain degree.

Bosch doesn't seem to have such a warning, but NGK does.
http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqgap.asp?mode=nml


Originally Posted By: antiqueshell
I know that an alternate gap for my car is .8mm or .032in do you think this would be more reasonable for the plug?

I have NO idea. Only VW knows how they designed your engine, and only VW knows what the proper gap is.

VW probably put a plug-gap specification in your Owner's Manual...



Amazingly no, there is no sign of any stated OEM gap for plugs ANYWHERE either in the original owners manual, or on the body itself...crazy. I do know that the European cars do show this on the emissions stickers but US spec cars from then do not.
No wonder VWoA can't make VW a success in the USA they never get stuff right, even if the cars themselves are very good.

 

[Trav]

Just what is the year and model of this car? US or Euro spec?
I have a lot of Bosch tech info you wont find on the Internet but 2.0 slow engine isn't giving me many results.

 

[Tegger]

Originally Posted By: Trav
Just what is the year and model of this car? US or Euro spec?

Very good questions. OP should give his engine's actual designation, not the displacement.

Maybe the OE gap really is 0.7mm (.028"), but I have a bit of trouble believing that it is.

Even in the old the old points-and-condenser days I remember gaps typically being well over .030".

 

[antiqueshell]

Originally Posted By: antiqueshell
Thank you Tegger!

You've got some of the best detailed explanations of almost anyone on this forum! Much appreciated, I figured that using the tool was the best way to go because you don't want to shock or jar the insulator or center electrode!

My car uses the VW ABA engine 2L and the OEM gap for a single side electrode is .7mm which is about .028in.



Here's the engine model designation. Sorry it got buried a page back.

Bosch in their parts finder site states a gap of .7mm or .028in.

 

[Whimsey]

Every VW I've owned, from Beetle to Rabbit & Golf had .028 gap spec for their plugs. You're talking about 1972, 1975, 1977 and 1985 vehicles.

Whimsey

 

[Trav]

Quote:
VW ABA engine 2L

Bosch is showing multiple gaps for this engine depending on location and year 0.60 0.65 0.70 1.1 mm are all on the list.
For US models 0.70 mm seems most common making the plugs you got less than ideal as the gap is 1.1 mm.

There were different piston head styles used in this engine
so just going by VW ABA engine 2L is a little tough, your current plugs are the best clue you provided and they spec 0.70

The Bosch gap limit is +- 0.15 mm, changing the gap on fine wire plugs is not recommended. I would get the same plugs it has in there now.