wrong spark plugs

[John M]

I have just removed my spark plugs for the first time from my 1108cc GTL. They were tight all the way out. So tight in fact that I feared striping the threads in the cylinder head. On inspection it looked like they were too long in the thread and the end of the plugs had carboned up making them larger at the end. The ones I took out were not the reccommended Champion L92 YC but Bosch FR7DC +8.
Comparing the two I can see the Bosch plug thread length is 19mm compared with the Champion 12.7mm. I don't know how much clearance there is in the combustion chamber but feel lucky to get away with it.
The only advantage though is that I needed a 16mm hexagon socket instead of a 21mm for the Champion which gave a bit more room.
Now without thinking I ordered a new set of plugs and I ordered the Bosch instead of the champion so what to do? I reckon I will make some copper spacers to go between the spark plug washer and the spark plug body unless anyone out there can think of a reason not to?
Yes I know I can buy some more plugs of the correct size but it does seem a bit of a waste.
Ho hum. These thing are sent to try us.
As a P.S. does anyone use copper slip when instaling spark plugs?

 

[Cornish4]

Hello John, just to confuse you further, the plugs I fitted recently to my GTL are Bosch, but the part number is WR8BC. These I bought from Mr Auto, and are the recommended ones. Yes the threaded part is long, about 19mm or so, but they are fine, no problems. As for using copper grease on the threads, not a good idea, as any left on the nose of the plug can bake hard and when you try to remove the plug it can damage the thread. Better to use just a smear of light oil.
Regards Brian

 

[JdeW]

This is a spark plug reference list I always use, I'm not familiar with the Bosch plugs.
The clearance is OK, enough spare space, and never use copper grease, a bit of oil on the threads is sufficient.
Regards, Joop

Spark plug table by courtesy of R-Quatre

 

[Cornish4]

Hello Joop, I noticed that NGK plugs are on your chart. Just a warning that recently copies of these plugs have been found on the market, and of course they are of inferior quality. I'm not going to say where it's thought they originate from, but I think we can all guess. They are of course labelled NGK.
Regards Brian

 

[John M]

Hi all, I just mentioned copper slip because I remember the plugs on one of the cars I had sealed with a taper rather than a washer and copper slip was recommended. Can't remember which car it was but it was an old one.
Just found the following which explains why I used to use copper slip.

https://www.driven2automotive.com/b...se-copper-grease-when-installing-spark-plugs/

Below is an extract.

Virtually all spark plugs now feature a special anti-seizure nickel or zinc-chromate shell plating. Basically, you can think of the plating as a replacement of thread compound or copper slip. Here’s what NGK says:


NGK spark plugs feature what is known as ‘trivalent plating’. This is a silver-or-chrome coloured finish on the threads that is designed to provide corrosion resistance against moisture, chemicals and weathering. The coating also acts as a release agent during spark plug removal. NGK spark plugs are installed at the factory dry, without the use of anti-seize. NGK tech support has received a number of tech calls from installers who have over-tightened spark plugs because of the use of anti-seize. Anti-seize compound can act as a lubricant altering torque values up to 20 percent, increasing the risk of spark plug thread breakage.

 

[Cornish4]

That's very interesting John, well worth taking note of.
Regards Brian

 

[JdeW]

Hello Joop, I noticed that NGK plugs are on your chart. Just a warning that recently copies of these plugs have been found on the market, and of course they are of inferior quality. I'm not going to say where it's thought they originate from, but I think we can all guess. They are of course labelled NGK.
Regards Brian

Thanks for the warning Brian, I will ask my main R4-parts supplier (R-quatre) if he's aware of that fact.
Regards, Joop

 

[Cornish4]

Hello Joop, you are very welcome. Yes it's as well to check this out, although I haven't a clue how to check whether plugs are genuine or copies. It might be obvious on inspection, but maybe not. I heard this from a good friend in the R4 fraternity, and who works on 4s for a living.
Regards Brian

 

[JdeW]

Hello Joop, you are very welcome. Yes it's as well to check this out, although I haven't a clue how to check whether plugs are genuine or copies. It might be obvious on inspection, but maybe not. I heard this from a good friend in the R4 fraternity, and who works on 4s for a living.
Regards Brian

Hello Brian, well the owner of R-Quatre (Jan-Willem) is a very respectible person, nowadays retired but in his workable live he had a Renault garage (over 30+ years) and he raced (r5 Alpine turbo), I've seen the photo albums and I pay him a visit once in a while. Now only R4's are his interest he repaired thousands of them...
He stands for the quality for the products he's selling and I know he just won't buy bogus parts, good aftermarket is OK, NOS even better.
ANd about the origin of the bogus spark plugs, well I think it starts with "ch" and ends with "inese"

 

[Cornish4]

Hello Joop, I met Jan-Willem at Renaultoloog a few years back, what a gentleman, and his family too, lovely people. I bought some brake parts, good quality and price, and last year I bought a radiator via the internet off him. I've got to say, I thoroughly recommend his company for Quatrelle parts. Yes I'm sure that he would make certain that the parts he's sells are up to spec.
Regards Brian

 

[petak]

Can someone tell me what is difference between L87Y and L92YC spark plug (Champion)

I have CHAMPION L87YC now in my R4 (688 D7-12)
Should I change them immediately?

 

[JdeW]

As far as I know the L87C is discontinued and replaced by L87YC
The L87YC gap is 0,9mm and has no resistor the L92YC gap is 0,8mm and has a resistor that varies from 6k to 15k Ohm
As long as the car runs fine leave it running because keeping an R4 running is all about tweaking, tuning and fiddling

 

[petak]

Car is working fine.....but maybe it will work better with L92YC

Long time ago (before big dismantling) I have used EYQUEM N43 with 3+1 mass electrode and it seems that engine was working perfect with them.
Nowdays it is hard to find them in Croatia

 

[angel]

L92 is a hotter plug compared to L87. Recommended for the 1108 engine, although in theory it needs colder plugs than the small engines (higher compression, leaner carb setup).

 

[mr-reno-139]

Fitting 19mm long spark plugs into a 1108 engine is not good idea for several reasons
1 carbon buildup on exposed threads inside combustion chamber resulting stripped threads when removing
2 increased compression ratio
3 increased risk of melting pistons due to spark igniting the spark too close
Post 1980 1289 cc c typevR5 mk1 engines and All1.4 use 19mm length as do all transverse 1108 R5 engines

 

[AdamWilkes]

As mr-reno-139 says - not a good idea, though I accidentally did this myself (in an 1108cc) with no permanent damage as far as I know. I guess compression ratio would increase a bit with extra plug-protrusion into cylinder space as well. Ran mine for 6000 miles before I realised, then spotted the carbon build-up on the excess threads.

Give the longer plugs away and fit the correct sized ones, a no-brainer.

 

[Richnd1974]

Just looking at the chart above, I have a 956cc in my R4 and the plugs are different that that of the 1108, should I replace mine with the Champion L92YC I have a feeling mine are based on the 1108cc that my local motor factor matched up and are Bosch plugs. Seems to run ok but I don't want to risk any damage

 

[AdamWilkes]

NGK BP6HS for my 1108cc (C1E 718) - same is suitable or your 956cc. They are the the short-threaded plugs and work fine (0.6mm gap). The Champion L92YC must have the same dimensions as the above NGK, as they are correct for mine too.

 

[mr-reno-139]

L is short reach 1/2 inch in champion range
N is long reach 3/4 inch
My preference is ngk bp6hs for short reach cars
Which if factory engine fitted is all of them

 

[Richnd1974]

I've just reinstalled the bp6hs...