674 replies to this topic

[TerrA LX]

I wass under the impression they needed to be replaced. How can i clean them? They are charcoal black.

Don't clean them if they are dirty, only fouled (fuel) can be cleaned easily and without damage.

Sounds like 9/10ths of your problem is old plugs, stop all tuning and throw a new set at it and see how it goes.

[TerrA LX]

The thing is if my plugs are not dissipating heat enough and allowing these deposits to coat the tip, wouldnt i want a hotter plug anyway?

It's the opposite, hot plugs dissipate less heat...

Sorry I missed, what is exactly building up on your plugs if it is not fuel it must be oil.
No amount of hotter plug will fix engine wear and will only make tuning a real PITA.

[S pack]

And bruce i had a look and it seems like NGK recommends a BP6ES for the LC XU1. 

Im running HEI, new coil, module, curved dizzy and spiral core leads. I'm thinking maybe i should try the colder plug and stuff around with the gap? is 1mm the norm? 

I've been running NGK BP6ES plugs in the 202 for years without any problems.

 

With the Bosch HEI ignition the recommended plug gap is 1.5mm.

[TerrA LX]

Just for shits and giggles, get a clean plug (if you don't have a spark tester) and open the gap right up (i mean bend the ground electrode right back), bung it in a lead and clamp the plug to a good earth, start the car and look for a nice big blue spark jump the gap.

If you go colder plugs the condition will worsen, hotter plugs might detonate if it runs well on the express way.
Select the right plug (reach) to suit your head with a 1.2mm to 1.5mm gap for the HEI.

If the plug burn feels good on the express way check the burn on them (you may have to pull over somewhere and let it cool before you foul them again) on the ground electrode to check heat range.

[FNQ]

When you say it was tuned , was it running well throughout the rev range,    it sounds as if you are too rich for the first part of the needle ( idle probably okay but then too rich , and then gets right again under a bit of load.

 

Do you know what profile needles are in the Sus ? , ( i don't know settings for Holden sixes but do play around twin SUs in my mini...  I would be tempted to get hold of a portable AFR meter and find out if the profile is right / giving reasonable AFRs...   as a fudge, you could dial the needles up the jet a known amount ( so you can revert back to stock if required and keeps them all in sync) and if it improves things in the stop , start , idle stakes  then it shows your needle profiles are set for blatting rather than all round   as suggested by 3 blind mice above   Darryl

[S pack]

Thats the thing. Why are colder plugs more suited to race applications and hotter plugs to every day situations, when a colder plug does less to burn off excess fuel? Or is that not relevant when poor tuning is a factor? 

Racing engines are regularly working in the upper rev range so combustion chamber temps are high for long periods of time so a colder plug is required to dissipate the heat quickly. The same race engine would foul it's plugs very quickly if driven on suburban streets at the posted speed limits. Besides the fact it would be a real pig to drive around town anyway.

 

  it sounds as if you are too rich for the first part of the needle ( idle probably okay but then too rich , and then gets right again under a bit of load.

 

Darryl

^^^ I somewhat agree.

Edited by S pack, 12 March 2014 - 08:07 PM.

[TerrA LX]

I do have a spark tester. Am i checking for strong ignition?

Yes, you should have a nice big fat blue spark, if it is yellow in any way then they will not be firing correctly.

Thats the thing. Why are colder plugs more suited to race applications and hotter plugs to every day situations, when a colder plug does less to burn off excess fuel? Or is that not relevant when poor tuning is a factor?

Higher cylinder pressures(temperature) and tune etc (usually in race conditions) can overheat a standard plug and going to a colder plug brings plug operating temp back to a normal range to prevent detonation etc (caused by the plug overheating, these conditions are normally bought on by too much comp for fuel, poor ignition timing, lean tune and incorrectly set idle stop).
Cooler plugs can foul easier at idle and off idle cruise conditions, not something that really concerns a racer.
You can check easily if you need a colder plug by looking at the burn on your current plugs.

I agree that a colder plug wont help me. If the XU1 ran a "6", i must have issues if i am fouling "5's". I'm thinking about trying a 4 but i dont want it to go bang!

I'm thinking you have a weak ignition and or a rich idle, off idle cruise condition.

FWIW BP6EFS-13 (1.5mm gap) is what is used in the VC-VH blue motor HEI.

As I said before, check new plugs against the oem plug for that head, some are longer and will screw in past the combustion chamber.

NGK list carbon fouling causes as rich fuel mixture, clogged air filter, faulty choke system, prolonged low speed driving or idling, faulty ignition system, over-retarded ignition timing and spark plug heat range too cold.

I hope this helps you better understand.

[TerrA LX]

Even just 300mls of the stuff in a tank does wonders...

How does the spark look?

[TerrA LX]

VB had points, that's why the gap is 0.9mm.
Even 1mm would be the bare minimum, they run a 1.5mm gap with HEI, as per the plug I suggested earlier, I would suggest starting at 1.5mm in the correct plug to suit your head (as the commodore plug may screw too far into your combustion chamber) and close it up to 1.2mm if you have high comp and you have experiencing high end miss.

I would be looking harder at cyl 3 and 4 slightly lean and test/substitute the coil and or HEI module to rectify weak ignition.

Edited by TerrA LX, 14 March 2014 - 01:56 PM.

[TerrA LX]

What part number coil do you have and is it getting full battery voltage via the ignition LT wire (yellow/pink ignition wire)?