Spark Plugs needed (advise please)

[Black_65]

Hi Guy's

Im looking to replace my spark plugs on my motor to something people say are good for street and strip use. I will be using nitrous on the strip, but use a colder plug for that and i have NGK DP8EA-9 at the moment.

current 2165cc spec is :

2175cc spec : C/R 8:5.1 BHP (unknown)

- Full Flowed Autolinea Case (all the good bits)
- 78.4 Stroker Crank (balanced)
- 94mm Mahle barrels and Pistons with Total seal Rings (balanced)
- H Beam Rods (5.5)
- CB 1.4 Ratio Rockers
- Engle FK10 Cam with straight Cut Cam gear
- 044 Heads with Dual Valve Springs 42 x 37 (wedge ported and polished by stateside)
- Shadek 26mm Oil Pump with Berg Cover
- 48 DRLA Carbs, stacks with covers
- Empi Deep Sump
- Lightened 8 Dowelled Flywheel (balanced)
- Kennedy stage 1 pressure plate with dalkin super disc
- Equaliser bottom pulley with billet bolt
- Saco Copy generator pulley
- 38amp Generator
- Doghouse with Oil Cooler
- 1 /58 merged header & box (speed shop)
- Accuspark performance coil, 8mm leads, 009 dizzy with electric ignition, rev-limiter
- Dog house tinware, Alt with race fan.

Any advice on spark plug selection will be great

Clarke
VWSP65

[richie]

D7ea for the street and D8ea for when you use the gas above hp level,I dont like the P part[projected tip] of the DPx ea range when using nitrous,and the 9 is to cold unless its real high compression or alot of nitrous

cheers Richie

[Black_65]

Wow, thanks richie 

Great help as i was runnig the 'p' plugs. ill order both sets now

[MeXX]

D7ea for the street and D8ea for when you use the gas above hp level,I dont like the P part[projected tip] of the DPx ea range when using nitrous,and the 9 is to cold unless its real high compression or alot of nitrous

cheers Richie

Hi

Like Richi allready pointed out D7EA and D8EA was my choice too.
On high levels (more than 150 HP) I had big problems with broken (not melted) ground straps and was unable to use them successfully.

The second thing is I don't think that a Kennedy stage 1 pressure plate with dalkin super disc will allow a shot that is worth installing a Bottle.


So keep on juicin'

MeXX
 

[spanners]

People slag Bosch plugs and rave over NGK, but only NGK fail mechanically, i too have had ground electrodes problems, from falling off, only minor engine damage fortunately, to ' moving about'  mainly closing up, but they lost temper and where very 'soft' and malleable, insulator porcelain split and broken, again minor bruising to the motor, ok , i may have chosen the wrong grade, but i was not miles of, ive been around the block lots,, .  ive also fitted many many thousands of stock and performance Bosch plugs, with never a failure, ive no axe to grind and i dont sell plugs, but this is my finding, on that basis, the NGK strike rate is , in a word, UNRELIABLE, keep an open mind.

[Black_65]

People slag Bosch plugs and rave over NGK, but only NGK fail mechanically, i too have had ground electrodes problems, from falling off, only minor engine damage fortunately, to ' moving about'  mainly closing up, but they lost temper and where very 'soft' and malleable, insulator porcelain split and broken, again minor bruising to the motor, ok , i may have chosen the wrong grade, but i was not miles of, ive been around the block lots,, .  ive also fitted many many thousands of stock and performance Bosch plugs, with never a failure, ive no axe to grind and i dont sell plugs, but this is my finding, on that basis, the NGK strike rate is , in a word, UNRELIABLE, keep an open mind.

Very good info there!

What 'bosch' plugs have you used that will fit CB 044 heads?

[Old Guy]

"Im looking to replace my spark plugs on my motor to something people say are good for street and strip use. I will be using nitrous on the strip, but use a colder plug for that and I have NGK DP8EA-9 at the moment."

Richie gave you good advice about using D7EA for the street and D8EA for the strip.  If the full number for the plugs you are using now is DP8EA-9 then the -9 at the end of the number has nothing to do with the heat range.  That number means it has a "wide gap" ground strap.  That is about the worst of both worlds.  Nitrous engines don't like much of the spark plug sticking into the combustion chamber.  The P means your current plug is a "projected nose" and the -9 means the vertical part of the ground strap is longer to allow for a wider gap.  That's just telling a nitrous engine "melt me, melt me".  Another thing you might verify when you have the heads off is that the plug threads end exactly where the combustion chamber begins.  You may have to "index each plug" to get them flush. There are different theories on where the ground strap should point.  Our experience on street or drag engines is that it doesn't matter as long as they are flush.  Since these 12mm plugs were designed for motorcycle engines, any decent motorcycle shop should sell indexing washers. Good luck.

Ron Barrett

[spanners]

I use copper sump plug sealing washers to index the plugs , sorry i missed the question about Bosch plugs, but as im working with wasser power these days and using 14mm plugs again,  im not up to speed with the smaller 12mm  size bosch numbers these days, but a local dealer will guide you, its all on the 'net as well.