9 replies to this topic

[robson]

Afternoon all and seasons greetings

I understand that one should goto a colder spark plug if the current ones are running too hot, but how do i tell if it is too hot? Surely it cant be as simple as just the temperature that the engine runs at? Which is affected by the cooling system!

Mine has a 4 core rad, no heater matrix, is a 1380 and runs always below the white temperature marker, which suggests the engine itself is cool enough, if indeed the spark plug temperature is in relation to the engine temperature

Is it just trial and error? Should i get some 7's? Currently using 6's

[Retro_10s]

This is a bit of a debate really,... plenty of people here Use the NGK BPE7's,... but plenty of people use the BPE6's too.

if there's nothing going wrong,... there's no real reason to swap anything, but you could always try some 7's in there anyway and see if it does anything.

If it aint broke, it probably doesn't need fixing

Edited by Retro_10s, 25 December 2007 - 03:26 PM.

[robson]

a good motto, if only i could stick to it

ill try some 7's, they are cheap anyway!

[sixwheeler]

All else being equal, you tell by having a look at the plug once it has run for a while.

See here...

[mineeeeee]

Afternoon all and seasons greetings

I understand that one should goto a colder spark plug if the current ones are running too hot, but how do i tell if it is too hot? Surely it cant be as simple as just the temperature that the engine runs at? Which is affected by the cooling system!

Mine has a 4 core rad, no heater matrix, is a 1380 and runs always below the white temperature marker, which suggests the engine itself is cool enough, if indeed the spark plug temperature is in relation to the engine temperature

Is it just trial and error? Should i get some 7's? Currently using 6's

Have you got a problem with your plugs?

The way i read the post your looking for a cure to a problem you dont have

[Dan]

The only real way to tell if the temperature is exactly right is with an engine ocilloscope on the rollers. The waveform will show if the plugs are running properly, if there is a serious problem however it will show as burned plugs or running on. If they are slightly out of range you won't really be able to tell and it won't hurt performance much.

[Big_Adam]

I got an ocilloscope if anyone need it.

:P

[Dan]

An electronics one or an engine one fitted to a diagnostic tuning machine and a set of rollers?

[robson]

guessing the usual electronics one

You are sort of right, there is no problem per se, but if i could be using more suited ones, i will

Plugs seem fine, tips are slightly brown in colour and the ring around the base is the usual black, but not severely so. Would suggest running slightly too lean, or possibly running too hot. Wouldnt be by much though. All of the plugs are like this and they are a year old. Just fitted a new set of 6's, might try some 7's ill see how these look after a while.

If say i required a non existing 6.5 plug, would it be better to use 6 or 7? what long term issues could appear? Thanks

[Dan]

Don't look so closely at plug colour, it's only a good guide to the health of an engine if you are using leaded fuel. Those detailed colour charts they put in Haynes don't work for unleaded. If the tip's brown it's probably OK. That's about as far as you can tell with unleaded. If the plug ceramic isn't cracking up and scorching and the tip isn't burning again it's probably OK. One more reason that now more than even it takes either a lot of experience or proper equipment to really go into detailed tuning.