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jha2297255 08-14-2008 08:56 PM

m103 spark plug ?
i tried to get bosch h9dc plugs at autozone and all they had was this
butttt it says R on it, so reading the 'dont use resistor plugs thing' It seems i shouldnt use these?

can someone give me a NGK (alleged to work better) plug number for 89 300e m103 engine, preferably one I dont have to order online.

the current plugs are bosch 'super' copper ones (green line on plug)

Arthur Dalton 08-14-2008 10:54 PM


jha2297255 08-15-2008 08:26 PM

napa couldnt get bp5efs or any non resistor NGKs at all

can i use this

NGK IX iridium 7397 TR5IX .030"

Arthur, what would be one heat range up? I have oil control issues and a + hotter plug would fix alot of that.

NGK iridium or regular? or no difference?


jha2297255 08-16-2008 01:41 PM

for those interested, NGK heat is 2hot -10 cold

so TR4IX is what im getting, im looking into non resistor magnecor or vitek plug wires since it seems non resistor plugs have gone way of dinosuar

Arthur Dalton 08-16-2008 01:52 PM

BP5EFS is a hot plug.
Motorcycle Shops have them.

kth286 08-16-2008 02:22 PM

In Uk Merc supplied me with the Beru equivalents for my E320 104 engine.

Same price as the old Bosch non resistor plug.

Call at your local Merc dealer for Beru or even Champion equivalent.

Arthur Dalton 08-16-2008 02:50 PM

The reasons the plug companies are going with R plugs across the line is bc the new computer cars are effected by stray RF interferance, whereas the older ones only concern was radio interference. [ spark frequency transmission].

I did some experimenting on an older classis IL 6 MFI chassis I own by eliminating the plug connector resistors on the wire ends and going with the newer R replacement plugs
[ standard Bosch R Coppers].. I found this to work well , but I then also found that the
Bp5es Copper non resistor worked even better and I still had no RF , mainly b/c you still have the R factor on the rotor/cap carbon and I also have a New JVC sound, who knows.
I love NGK plugs, specially the last few years when I had plenty of trouble with the India Bosch..

Something to consider.
What I do not recommend on the older ignition sistems [ and Waste Spark ones] , is to use R plugs topped off with A Resistor Plug connector.........

Ferdman 08-17-2008 09:49 PM

Arthur, why wouldn't Bosch F8DC4 spark plugs be acceptable for the 103 engines?

Arthur Dalton 08-17-2008 11:01 PM


Originally Posted by Ferdman (Post 1941535)
Arthur, why wouldn't Bosch F8DC4 spark plugs be acceptable for the 103 engines?


Physically different...

One is a tapered seat plug [ Conical seat ] and the other is a compression Ring gasket plug [ Flat seat]
H and F ..completely different head seating.

jha2297255 08-18-2008 09:38 PM

FYI magnecor has M103 wires in stock and they are non resistor, $81 shipped in USA

got them coming in sweeeet

jha2297255 09-03-2008 12:34 AM

soooooooo TR4IX has non removable terminal, had to send em back for TR5IX, oops

coming friday!

i got a new MSD blaster ss coil mounted over by ABS module w 8mm Magnecor USA made wire (plug wires to be installed)
mountd coil thru drain plug hole w 5/16 bolt welded to aluminum plate then vibration mounts for coil.

NB! magnecors 'stock' coil wire WILL NOT work with bosch coil, its wrong end, male no female. bc i got both.

new coil = smoother revving, still some idle shakiness after 2-3 minutes, new plugs+ wires shld help on that. stay tuned

jha2297255 09-03-2008 12:35 AM

just to clarify magnecor wires are 'normal' spark plug tip, but i wanted removable terminal style plugs in case i had to revert to bosch wires

jha2297255 09-05-2008 02:45 PM

6 new nGK plugs = woah!

hugeeeee difference! revs so much freeer up to 6grand ez, doesnt bog down idels super smooth , i managed to go fast enough to scare myself on some windy road test drive

heres old plugs, very ashy deposits on all, need to get valve seals done for sure

new plug wires, very close fit by visc fan, these are 8mm thicker than stock, zip ties are temporary

my plug wire plastic thing is shot

gotta love i6, changed plugs+ wires in an hour!

Tims450SL 09-05-2008 09:37 PM

i like that- how much was the coil? I thinbk I am gona do the same thing- so the plugs (6) were that much??you gotta be kidding me!

jha2297255 09-05-2008 11:27 PM

coils $60 shippd from jegs

the plugs werent woah expensive, more like woah how crappy the old plugs were (almost all had serious insulator damage) and how much sweeter the engine works with new ones. i think $35 from

magnecor plug wires come in other colors in 10mm, 7mm is black , 8mm is blue,

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