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Tue Sep 29, 2015 11:34 pm

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.

Wed Sep 30, 2015 3:47 am

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.

Wed Sep 30, 2015 8:34 am

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):
Quote: Low numbers refer to "cold" spark plugs, which have low thermal absorption in hot engines (like in a Ferrari).

High numbers refer to "hot" spark plugs, which have high thermal absorption for cold engines (like a VW Beetle).

I always though of VWs as "hot" engines due to oil and operating temperature, but maybe they mean something else, like combustion temperatures or compression ratios?

Are the W8 plugs still recommended for stock engines?

Wed Sep 30, 2015 10:37 am

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

Thu Oct 01, 2015 8:29 am

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.

Thu Oct 01, 2015 10:04 am

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

Thu Oct 01, 2015 11:39 am

raygreenwood wrote: Whats unique about the BP6ET and the Bosch W7DTC....is the electrode configuration.

Pay attention.....to the fact that they are 3/4" reach. Stock style tyoe 1 hwads cannot use them unless you have aftermarket heads set up for 3/4" reach like a type 4.

That being said.....i would bet that ir i looked at the Bosch or NGK identifier chart....i could pull up a part # for the triple electrode for type 1 heads and thread reach. Now....whether its in stock anywhere...who knows. Ray

ah ha.....thanks.

Thu Oct 01, 2015 12:17 pm

So try some DCP8E ;-)

Thu Oct 01, 2015 12:47 pm

so the NGK BP6ET should work with the 044 heads?

Thu Oct 01, 2015 1:18 pm

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.

Thu Oct 01, 2015 1:25 pm

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

Thu Oct 01, 2015 6:32 pm

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

Thu Oct 01, 2015 7:02 pm

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.

Thu Oct 01, 2015 8:55 pm

raygreenwood wrote: ..... 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

Thanks Scott and Ray, for the very pertinent - albeit found-too-late info. Like I said, I just found this thread today. I installed the BP6ET's about two weeks ago without doing my own research. Last night we finally got the fuel pump safety relay and gauge wiring straight, and got it cranked.

If I decide to retry the triple electrode route, I'll reenergize my research. Till then I'll stick with my Bosch WR8ACs. We're ready to ride.

Thanks for sharing good info, and not just "RTFB".
Greg

Fri Oct 02, 2015 1:04 pm

andy198712 wrote: so the NGK BP6ET should work with the 044 heads?

044 have 12 mm plugs, so a D#### plug, B#### are 14 mm plugs.

Fri Oct 02, 2015 2:02 pm

vince1 wrote: andy198712 wrote: so the NGK BP6ET should work with the 044 heads?

044 have 12 mm plugs, so a D#### plug, B#### are 14 mm plugs.

So...are you saying the 044 heads have 12mm diameter spark plug threads? I doubt it.

Also you are mixing up what you are stating because you are writing the plug code in the incorrect order. If a Bosch plug part # has a "D" as the FIRST number in the code...... that would me an that it has 18mm X 1.5 diameter threads. Like... D####....that is a 18mm x 1.5 thread plug

A plug with a B as the first letter in the code.....like B#### (Bosch part # again).....does not exist. There is no "B" first digit code.

The two numbers I posted W7BTC and BP6HT...break down like this

W7BTC:
W=14mm x 1.5 thread diameter with 20.8mm wrench hex
7= Heat range
B=12.7mm thread LENGTH with a washer style seat
T= triple electrode
C= Copper

BP6HT
B= 14mm x 1.5 thread diameter
P= Projected insulator
6= heat range
H=12.7mm or 0.5"" thread reach/depth
T= Triple electrode

All f the plugs we are speaking of have 14mm diameter threads. The difference we are speaking of here is the LENGTH of those 14mm threads.

The W7DTC and BP6ET...all have 19mm thread length and 14mm x 1.5 thread diameter

The W7BTC and BP6HT...all have 12.7mm thread length and 14mm x 1.5 thread diameter

Ray

Fri Oct 02, 2015 2:26 pm

Quote: So...are you saying the 044 heads have 12mm diameter spark plug threads? I doubt it.

These 044s I just hand ported say they do. They are 12mm- 3/4". Dr7s went in them.

Fri Oct 02, 2015 4:12 pm

jfats808 wrote: Quote: So...are you saying the 044 heads have 12mm diameter spark plug threads? I doubt it.

These 044s I just hand ported say they do. They are 12mm- 3/4". Dr7s went in them.

Wow!...learn something every day!

Thank you!. I know that most 044's I have seen had 14mm threads...so obviously they are available with both.

Its actually pretty smart. I was thinking about doing that on my type 4. Easier to do some interesting thing with CHT connectors I am working on.

Again...thank you for the correction!

So....if a triple electrode plug was needed for those like those we were speaking of earlier...these would be the part #'s

Bosch:
X or V= 12mm x 1.25 thread with 14mm hex wrench (very thin) or 17.5mm hex wrench
7= heat range
A, B or G= 12.7mm thread depth, flat gasket with normal, mid level or long extended insulator or
T= Triple
C= Copper

I find no listings in the copper/super series but there are plugs like that in the super plus and others. Ray

Fri Oct 02, 2015 5:41 pm

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.

Fri Oct 02, 2015 10:09 pm

raygreenwood wrote: vince1 wrote: andy198712 wrote: so the NGK BP6ET should work with the 044 heads?

044 have 12 mm plugs, so a D#### plug, B#### are 14 mm plugs.

So...are you saying the 044 heads have 12mm diameter spark plug threads? I doubt it.

Also you are mixing up what you are stating because you are writing the plug code in the incorrect order. If a Bosch plug part # has a "D" as the FIRST number in the code...... that would me an that it has 18mm X 1.5 diameter threads. Like... D####....that is a 18mm x 1.5 thread plug

A plug with a B as the first letter in the code.....like B#### (Bosch part # again).....does not exist. There is no "B" first digit code.

The two numbers I posted W7BTC and BP6HT...break down like this

W7BTC:
W=14mm x 1.5 thread diameter with 20.8mm wrench hex
7= Heat range
B=12.7mm thread LENGTH with a washer style seat
T= triple electrode
C= Copper

BP6HT
B= 14mm x 1.5 thread diameter
P= Projected insulator
6= heat range
H=12.7mm or 0.5"" thread reach/depth
T= Triple electrode

All f the plugs we are speaking of have 14mm diameter threads. The difference we are speaking of here is the LENGTH of those 14mm threads.

The W7DTC and BP6ET...all have 19mm thread length and 14mm x 1.5 thread diameter

The W7BTC and BP6HT...all have 12.7mm thread length and 14mm x 1.5 thread diameter

Ray

Was talking about NGK part numbers