Sparks..

[Chris Y]

I'm just in the process of buying some new spark plugs for my 1600 engine, which is only mildly tuned (std. cam, vernier with quite a lot of advance, bored out to .040), and am confronted by an array of different types of spark plugs, wondering if any are realistically 'better' than the rest for my engine..

As standard, the engine should run BCP6ES (NGK code) plugs. However, it generally runs 7s rather than 6s because the 7 is a slightly colder plug.

Currently it's got 4 BCP7EV plugs in, which are the Gold Palladium electrode. Technically these are now obsolete, however they can be replaced by BCP7EVX which is apparently a platinum electrode.

There are other types as well, including Irridium, which is horribly expensive (obviously).

The question is, do these rare metals really make much of a difference, and for a mildly tuned engine like mine, are there any recommendations?

[marcush.]

you will only know by trying ,actually...
but be aware of engine knock,so have something at hand to listen to high speed detonation.
I really believe in NGK Plugs ,and have found huge differences between plug design and brands .But this is surely engine dependant so I can only say give it a try!

[Dave Brand]

Originally Posted by Chris Y

The question is, do these rare metals really make much of a difference, and for a mildly tuned engine like mine, are there any recommendations?

I'm by no means an expert on these things, but I think the advantage may lie in plug life rather than performance.

[Chris Y]

Funny you should say that, but the Gold Palladium plugs that are fitted now have had the shortest life span of any plug I've ever fitted..

However, that may be more the car's fault than anything else. It has a history of bizarre electrical 'issues', ranging from melting transponders, intermittant cut-outs (which we now think may have been a wiring short) and comedy pop-off HT leads.

[ian_w]

Platinum plugs have a very long life, in production cars change intervals are typically 60k miles. However as Platinum is a precious metal they are quite expensive ( typically £10 per plug ).

NGK make some impressive claims for their Iridium plugs, although in my experience spark plugs make little or no difference to engine performance - the mixture either goes bang or it doesn't!

I bought some BKR7EIX Iridium plugs recently for my racecar and they cost a quite reasonable £5ish each. Only went for Iridium as NGKs range for M14 plugs with 16mm hex ( the 'BK' bit of the part number ) was very limited in a 7 grade.

It sounds like you just need 'normal' plugs, ES or EV types are probably what you need - they have no fancy metals.

What sort of engine is it - iron or aluminum head? For the modest changes you describe I would have thought that the standard 6 grade would be fine. If you go too cold, you will get plug foulling - black carbon deposits ( which is often mistaken for excessively 'rich' mixture ). Foulling will eventually lead to misfires as the spark tracks across the carbon rather than jumping the plug gap.

NGK plugs tend to have a wider heat range than other brands, this means they resist both cold foulling and high temperatures better than other plugs.

[THR]

ive never noticed any diff with any plugs!! lol

new ones are better than old ones thats all i can say.
but then i only ever bought cars with 50k on the clock. (poor ya see) lol

think we tried expensive ones in the race engine, and after a bit changed to the cheaper ones.. which seemed the same lol.

i know we once had a failure of a spark plug after it being in the BDA for 3 years, but then it was only used four 50 secs at a time in a hillclimb!

[gttouring]

well ideally you would know th e needed heat range of the plug to match your engine.
and on top of that you could understand the various proprietary designations for heat range per company...
that said, check out the plug types for the engine manufacturer- that is what they choose, especiallly for higher performance engines, this should help pick the best plug for your app.
remember if the plug is to 'cold' it will not get hot enough to self clean and will foul, if it is too hot it will keep heat and preignition will occur.
so finding the best one isn't so hard just have to know where to look. Try the 'hotter' 2.0 engine of the same manufacturer and the regular 1.6, compare the numbers-the code and even check a 'hotter' motor and find the one a tick up from the 1.6 stock you have...note that a manufacturer always plays it safe, and in doing so the range they pick for plug performance is leaning towards reliability and even performance not flat out edgeness, which wouldn't work on the coast vs. the highlands.

[R59]

Bottom line is suck it and see. Looking at the mods you have done to your engine, I'd say stick with the standard heat range.

I used ones that were too cold once, and I lost lots of top end performance.
I've used ES's EV's ECV's but always came back to ES's as I'd change the plugs after two races regardless.

The one thing I did notice a few years back - when I changed from 4* petrol to Optimax, how much cleaner the plugs were....

Rob.

[marcush.]

with unleaded your plug reading is much less obvious as it was in the good ol days....

I found marked differencies in plugs ,with something crude like a Rover/austin A-series engine,wich liked champion and NGK plugs but was a mess with Beru and bosch.
if your HT plugs pop of the plugs ,quick erosion of the electrodes is a matter of fact as long as the engine is still running on all four pots.

[Chris Y]

Thanks all for the replies.

I've decided to go with the 7ES plugs for the moment. I'm doing a little bit of testing before the race, and will have a look at the fouling on the plug to see whether they're too cold. The engine runs a little rich anyway, so it may be difficult to tell. It's certainly had fouling issues in the past, but I put that down to the fact that it's had all sorts of electrical problems and hasn't done many laps at anywhere near racing speed.

I also have some 6ES plugs with me, so no worries - will suck and see

Just for interest's sake, the head is iron, and the 2.0 version of the engine (well, it's quite a bit different really) uses the 6ES plugs too, as does the turbo version of the 2 litre. Runs on Optimax fuel.

[marcush.]

oh one more hint:

I did not work with engines quite a while but i think the E in the Name of the NGK plugs stands for extended tip .
this is especially for lean burn ,cold start etc ...and not really for a high performance engine 8with high compression and big risc of detonation),

I would look for the retracted or normal tip length instead for a race engine.

NGK had a very detailed mastercatalogue not long ago ,and perhaps has still.
You could actually see pictures of the electrode designs anmd graphs about heatrange comparability from plugline to plugline,wich helped a lot when deciding on plugs.

And the V denotes fancy metal normally palladium...but they also used the v
vor some special electrode profile if i remember correctly..(v-line)

I´d play it save and go for the 8 plugs and see if its fouling .
You can see if the plug is in the correct heat range by looking at the centre electrode.
If there is a blue annealing ring developing just under the top surface of the centre electrode you should be in the ballpark.

[Russ-Turner]

http://www.vf750fd.com/blurbs/plugs.html