Which Spark Plug ??

jfats808 · Posted: Tue Sep 29, 2015 11:34 pm Post subject:

Vince,
Thanks for the recommendation. I'm wondering about the resistor type plugs with my cb ignition. That's why I've been hesitant switching away from my dr8ea-9s.
I also see an iridium version. I might try a set after my next oil change.
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Kjell Roar · Posted: Wed Sep 30, 2015 3:47 am Post subject:

As long as the resistor plug is not specified as necessary for the ignition system, don't use them. They are more fragile, and malfunction a lot easier.
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KTPhil · Posted: Wed Sep 30, 2015 8:34 am Post subject:

I always used the stock Bosch W8AC, which seemed to be the closest to the old designation W145. I've seen a few old VW manuals which called out the 175 series (W7 today). Why the difference?

From Bosch's website (oddly enough):

Scott Novak · Posted: Wed Sep 30, 2015 10:37 am Post subject:

The only reason for using a resistor spark plug is to improve RF suppression.

However, a good set of low loss inductively wound suppression ignition wires cures the radio interference without any significant reduction in spark current or voltage available to the spark plugs. Ignition wire with a resistance of 300Ω per foot or less is what you should be looking for. You don't need to go much lower than that either. A small amount of resistance in the ignition wire does benefit RF suppression.

The resistors just further limit spark plug current and reduce the voltage available to the spark plugs a bit.

You should also use a resistorless rotor or bypass the resistor inside the rotor by soldering a wire between the rotor center contact and the rotor tip.

Just by replacing the stock resistor style ignition wires with low loss inductively wound suppression wires, replacing the stock resistor rotor with a resistorless rotor and using non-resistor spark plugs you can easily open your spark plug gaps 0.005" wider for improved performance.

Scott Novak

jfats808 · Posted: Thu Oct 01, 2015 8:29 am Post subject:

Mark at CB got back to me. He said only use conventional copper core plugs with cb crankfire. Guess I'm stuck with the d8ea-9s, which work fine actually. Just an FYI for cb crankfire users.
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2276 IDA's 86C 11-1 DD

Scott Novak · Posted: Thu Oct 01, 2015 10:04 am Post subject:

Here is information to read the NGK spark plug codes.

https://www.ngk.de/fileadmin/Dokumente/EN/download...ode_en.pdf

https://www.ngk.de/en/technology-in-detail/spark-plugs/how-you-crack-the-ngk-code/

http://www.ngksparkplugs.com/docs/tech/design_symbols_plugs.pdf

About the only time you will get better performance than a projected copper core spark plug is if you have a weak ignition system that needs all the help it can get.

Copper core spark plugs may not last as long, but they perform better and will yield better gas mileage, as long as you have an ignition system that can fire them during all engine conditions.

If someone wants a maintenance free engine they shouldn't be using a flat tappet cam that requires checking the valve lash frequently. They shouldn't be driving an air cooled engine that requires a valve job every 50,000 miles. So don't wimp out on your ignition system and don't whine about more frequent spark plug replacement.

Scott Novak

jpjohns · Posted: Thu Oct 01, 2015 11:39 am Post subject:

vince1 · Posted: Thu Oct 01, 2015 12:17 pm Post subject:

So try some DCP8E Wink

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andy198712 · Posted: Thu Oct 01, 2015 12:47 pm Post subject:

so the NGK BP6ET should work with the 044 heads?
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kentga

Just found this thread - - a week too late. Not even sure how I wound up here... fate's fickle finger I guess. New 1776cc, possibly cracked pistons. Ugh.

Haven't checked my compression yet, but she still cranks (with my old Bosch 1/2" reach plugs).

Few weeks ago, I skimmed through all the plugs AirCooled.net offers, thinking I was paying attention to the descriptions... The ACN recommendation on the BP6ET sold me. I immediately snapped up a set, ass-uming my [stock] heads would handle the BP6ET's 3/4" reach projected tip.

Installed the new plugs along with a new Carter electric fuel pump, and new CB Performance dual IDF-40s. We spent the next few nights scratching our heads over the stumbling and backfiring, fuel pressure issues, and erratic timing.

Finally pulled this plug (#1) to read the burn profile... only to find that two of the four new plugs had kissed pistons - the pic shows #1, the worst. Will be running a compression test when I find my gauge. Can't imagine there's no damage to the piston - there were all kinds of metal filings in the plug hole when I pulled this one out. Plug in #3 was lightly whacked, and those in #2 and #4 were fine.

Thought I learned about 30 years ago not to assume away anything important. Guess I learned it again.

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Scott Novak · Posted: Thu Oct 01, 2015 1:25 pm Post subject:

Even with the stock 12.7 mm spark plug thread length (Reach) I always check the heads to make sure that the spark plug is at the correct depth and that there are NO exposed spark plug threads. I adjust the reach of the spark plug with copper washers on the spark plug.

I also index the spark plug so that the outer electrode is NOT shrouding the spark plug gap to the incoming fuel mixture.

Scott Novak

raygreenwood · Posted: Thu Oct 01, 2015 6:32 pm Post subject:

If its a type 1....and has standard head design (not aftermarket)...as I MENTIONED....a few posts back......the NGK BP6ET and Bosch W7DTC. ....will NOT fit your heads.....because those are 19mm reach and the type 1 is 12.7mm reach as Scott just pointed out.

If you go to the web and pull up the Bosch or NGK chart....and match up your curfent plug by the letter codes... very quickly you will find a plug that WILL fit.....as I also MENTIONED.
Wink

The DTC in these plugs stands for: D=19mm reach....T= triple electrode.... C= Copper

What you want for a type 1 in this same kind of plug is a W7BTC or W6BTC.
B=12.7mm....T=triple electrode......C=copper.

The NGK part # is BP6HT.

As i also mentioned. ...you may have trouble finding those. Some Triumph cars and motorcycles used them as well as some italian cars. I am not sure what else did.
Ray

Howard 111 · Posted: Thu Oct 01, 2015 7:02 pm Post subject:

I run the Bosch Super, copper core, W8AC on a turbo, FI, 2 liter, in my hotrod '73 Ghia. MSD ignition. Never a problem, on or off boost.
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kentga · Posted: Thu Oct 01, 2015 8:55 pm Post subject:

vince1 · Posted: Fri Oct 02, 2015 1:04 pm Post subject:

raygreenwood · Posted: Fri Oct 02, 2015 2:02 pm Post subject:

jfats808 · Posted: Fri Oct 02, 2015 2:26 pm Post subject:

raygreenwood · Posted: Fri Oct 02, 2015 4:12 pm Post subject:

jfats808 · Posted: Fri Oct 02, 2015 5:41 pm Post subject:

I prefer 12mm plugs over 14 for any build personally. More plug boss area. Less probability for cracks. Makes even more a deal when running 44 and up valves imo.
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2276 IDA's 86C 11-1 DD

vince1 · Posted: Fri Oct 02, 2015 10:09 pm Post subject:


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