Wrong spark plugs?

[Candycj1]

Hi all

After wasting nearly 2 hours trying to remove the plugs on my 11/87 635 today using the standard 21mm socket, I belatedly discovered it had 16mm plugs - Bosch FLR8LDCU+ to be precise. I was / am going to fit a set of WR8LC+ which appear to be a correct replacement for my model year - anyone have any thoughts on whether the ones that were in there would have caused any problems?

Thanks
James

[86_6series]

Questions you may want to ask.
https://www.boschsparkplugs.net/learnin ... -selection

Bosch listing for 1987 635
Check out the different specs.
WR9LS
https://www.sparkplugs.com/product.aspx?zpid=8290

Not listed for 1987 635
WR8LC+
https://www.sparkplugs.com/product.aspx?zpid=8156

Not listed for 1987 635
FLR8LDCU+
https://www.sparkplugs.com/product.aspx?zpid=8104

[plip1953]

Real OEM shows W8 LCRs for a Euro 635 auto 11/87 car.

And that's what I use in my 12/87 635 Highline.

[Candycj1]

Thanks for the input guys. The WR8LC+ vs W8LCR debate seems a common one - there are various threads out there where people have ordered the latter and been sent the former, being then told they're simply the new version / name; inevitably some posters disagree with that view and explicitly warn against using them, though don't say what difference they would make...

...i had read that the W8LCRs weren't available any more which is why i went with the WR8LC+ when i found a set - FCP Euro lists them as compatible with the E24 but only the highline / b35 engine as of 6/87 (so should be ok in my car).

Curious about the designation differences I dug around more and having looking at the Bosch designation decoders, e.g. http://br.bosch-automotive.com/media/pa ... ung_de.pdf, the only difference i can find is the the R at the end means it has a burn off resistor whereas the R as the second letter denotes it has a suppression resistor. Interested if anyone knows if this difference is material - i would imagine a burn off resistor also suppresses interference, not sure if an interference resistor affects burn off though, or if i should care. Oh, also the '+' apparently means an yttrium enhanced copper core supposedly giving longer life - but fundamentally its still copper.

Incidentally the differences with the FLR8LDCU+ that came out of mine appear to be 1) the hex socket size is 16 not 21 (the 'F') - can't see that matters, 2) its a 'surface air gap' plug (the 'first L') - supposedly exposing the spark better but with caveats, 3) it has a double electrode (the 'D') - i would guess that's to give a bigger spark area and 4) it has a 1.0 gap (the 'U') - which i would think is related to the design - that would be a huge gap for a 'regular' plug (the standard W's come pre-gapped at .3mm).

Apparently the FL plug is what the M60 engines use. I have had some intermittent running issues with mine, will see if the W plugs make a difference and will report back if so. My thinking here is that without a bigger coil, my engine may not be making a big enough spark with the FL plugs which might explain why it runs poor when hot and smells of fuel - incomplete combustion...? Doesn't explain why its intermittent though, maybe the coil is on the way out or of course maybe its nothing to do with the spark (or more likely and hardest to solve, its a combination of a bunch of things...)

[86_6series]

I use Autolite #66 in my 6. Yeah, I can't enough of 6's.

Seriously, years ago I ran a highly modified 510 Datsun.

When I switched to Autolite I could rev another 400 revs
higher without breaking up and the car pulled stronger
reducing lap times about 1/2 a second. Been using
them ever since.

just my $.02