What sparkplugs to use N9YC or N12YC

PepijnWK

Active Member
#1
I have a Rover with a SD1 EFI engineblock. It is an old one with the flapper injection. Iginition is in distributor Lucas 35DE8.
My questions is what sparkplugs should I use? the champion N9YC or the N12YC?
Now present are the bosch w8dc



thanks in advance for the info!!
 
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#2
I'm not sure which heat range, but I can tell you I wouldn't use a Champion brand. Personally I prefer NGK but in my eyes pretty much any brand is better than Champion.

Yours
Vern
 
#3
I'm not sure which heat range, but I can tell you I wouldn't use a Champion brand. Personally I prefer NGK but in my eyes pretty much any brand is better than Champion.

Yours
Vern
I agree with you there. Champion plugs have fouling issues. I like NGK's.

I fly small planes, and they always seem to run Champion plugs. I guess Champion thought that fouled plugs would be less of an issue on dual spark plug motors. I have only ever cancelled one flight due to a mis fire when checking the mags prior to flight. It is more of a problem in places like Colorado with high altitudes on the ground.
 

sdibbers

Well-Known Member
#4
Having just ordered Champion RN7YC plugs and having to get a replacement for one with an extra high internal resistance I have to agree.
 

PepijnWK

Active Member
#5
So testing before fitting is in order! I asked the question because some sites say N9YC and some say N12YC depending ion the year. I once bought a bunch of champiobn plugs for my motorcycle off a guy I know. He has bought a lot of those plugs and they are cheap . Less than 80 pence a piece if you buy 24 or so. So that's why I ask. The guy sells them cheap . But i am not sure which one to buy for the Rover.....
 

sdibbers

Well-Known Member
#6
So testing before fitting is in order! I asked the question because some sites say N9YC and some say N12YC depending ion the year. I once bought a bunch of champiobn plugs for my motorcycle off a guy I know. He has bought a lot of those plugs and they are cheap . Less than 80 pence a piece if you buy 24 or so. So that's why I ask. The guy sells them cheap . But i am not sure which one to buy for the Rover.....
Testing is certainly worth it with resister plugs they have an R in the part number.
 

sdibbers

Well-Known Member
#8
I would look at the last specs for an EFI SD1. They would change the specs as they got more data. Unfortunately I run a four cylinder car so can’t recommend anything.
 
#11
I think the Champions are worth every cent/penny that you pay for them. After a string of plug failures in everything from cars to lawnmowers and chainsaws I now prefer to use almost anything else that I can get.
 

sdibbers

Well-Known Member
#14
Yeah, I found classic mechanic blog where the blogger reckoned on 10% being the failure rate out of the box. I’ve had to replace them out of the box because of bad internal resisters in recent years, next plugs will be NGK I’m afraid.
 

PepijnWK

Active Member
#16
do we need a resistance in the plugs? if yes why is it better for the electronic ignition? as I have the Lucas Opus system.......
 
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cobraboy

Well-Known Member
#17
I was told don't run resistor plugs with resistor leads. I have had another car since 1993 with a Rover V8 and Opus ignition, it has resistor leads and non resistor plugs ( NGK BP6ES ) and has always run clean. It has a 3.9 with Typhoon cam, Rhoads lifters, ported heads, long tube headers, Offenhauser, 390 Holley, re curved distributor and as I have said a stock opus electronic ignition, which everyone says is rubbish. It made 240 bhp on the rollers when new and has never missed a beat.
 
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