Spark Plug Query

[kyteler]

Being I'm eliminating things one by one, and plugs were one of those things, I remember my brother's old dismantled 2.8L Supra engine was in the garage and I thought well $^!#, that's got plugs, being I only need them for a bit of a test for the time being I'll give it a go if they match up.

They're actually NGK BPR4ES, will these be too hot to run in my L24 for exended periods of time or be OK?

The plugs that were in there were BP5ES plugs, which as I understand it is one step hotter than factory recommendation, so, the 4's will make it two steps hotter, but I don't know, is that still within limits?

Again, any help appreciated.

[sjcurtis]

kyteler,

hi,I am not sure exactly what you are trying to rule out.

For my money normal operating plug heat range for the L series engine (not full race) cool BPR7ES, warm BPR6ES, hot BPR5ES, the variables are condition and usage. does this help

cheers

Steve :classic:

[kyteler]

Oh sorry, I was trying to rule out the plugs as reasons for a slight miss.

And just wanted to make sure 4's weren't too hot to use for extended periods of time, because if they are ok I'll use them until I can afford a set of 6's, I know plugs are cheap but I'm a pauper. :classic:

I'd hate to screw the engine or electrics up somehow just because the plugs were too hot.

[sjcurtis]

inspect your plugs. the oily dark one replace it with your hot plug see if the miss goes away if yes buy 1 BPRXES to fill the dead plug position. It will get you bye for now.

cheers

Steve :classic:

[Daniel]

Steve what is the "X"plug? Also I notice the lower the number the hotter the plug.Does this hold true for other plug vendors or just NGK?Is it a industry standard type thing? Is your Z carbs and points? Thanks,Daniel

[kyteler]

Japanese plugs works on a "smaller number hotter plug" basis NGK, Denso etc.

American or Other plugs are the other way around "bigger number hotter plug" Champion, Autolite, etc.

ie.

NGK Champion

BPR5ES = N11YC

BPR6ES = N9YC

BPR7ES = N7YC

Also, I've just read on the NGK site that it's better to err. on the side of colder, as a colder plug will only foul at worst and a hotter plug can cause severe engine damage.

Sounds nasty.

[sjcurtis]

Hi Daniel,

the X denotes the numbers 7,6 or 5 in the BPR series of plugs in the case above to match what is already in the engine. to enable kyteler to buy the right plug.

As to heat range I only ever use NGK, but I believe some brands do the same type of coding. ( NGK rules, other brands only get you to the breakdown lane)

I run 82 ZX mitsubishi air gap style distributor with external square IC pack.

I run standard 6/82 ZX Annolog injection with all factory components wired in and run trimmed by steve.

cheers

Steve:classic:

[gramercyjam]

I run BP4ES on my autox L24 'cause I run a little rich with big triple webers and the slightly hotter plug keeps the plugs a little cleaner. No overheating with stock radiator, 2 10 inch electric fans.

[kyteler]

Oh, OK.

But what if it didn't have as much fuel to burn could it then cause problems?

I just got my "How to Modify a Nissan/Datsun OHC" book and they don't even list the 4 in their range of plugs, the lowest (hottest) listed is a 5 so I was getting a bit worried.

However though, sounds as if they'll do until I can get some 5's or 6's

Thanks for your help everyone.

[gramercyjam]

Now I am not sure if they are 5 of 4. I'd need to look. Anyway, what you do is check 2 things besides just the temp gauge. Check to make sure the piston doesn't hit the nose of the plug at TDC and check to see if the electrode is melting (those nice square edges getting rounded off at the tip) after you have run it a while.

--John B

[kyteler]

CRAP DAMNIT!

I bought a new set of plugs, put them in, there was still a ever so slight hint of a miss, took the car for a bit of a run, on the way back the miss wasn't a hint anymore it was back to the way it was, CRAP! I thought.

Got home, gave the car a rev, still, a slight miss was there, went to give it another rev and sit it aroun 2000rpm, but no, it cut on me, tried to restart it, to no avail. (at least I got home)

Checked for spark from the coil, again, there's none, now I've got to go get another frikking condensor to try because I think it's killing them, what the hell could be causing it to kill condensors?

However, I think I have my hands on a L20 Turbo 6 Skyline electric dizzy for not much but I'm not sure at the moment, still, I guess I'll have to wait to see if I can get one to see whether the miss is still there with an electronic dizzy.

Again, if anyone can help, let me know, otherwise I'll just let you know how things go with a leccy dizzy later on when/if I get one.