Preferred Stroker Plugs

[Comanche91]

Hesco recommends the traditional OEM Champion copper core RC12LYC for my 4.6L stroker. I have heard mixed reviews of alternatives, like platinums (never!) and NGK copper 7252 (yeah!). Due for replacement, and I'm considering the NGKs. Any opinions? Thanks; Don

[John]

I run the Champion RC9's. I suspect the NGK's would do fine in the copper core flavor. The fancier a plug gets, the less likely it will perform in these motors.
John

[whitey2001]

Hesco recommends the traditional OEM Champion copper core RC12LYC for my 4.6L stroker. I have heard mixed reviews of alternatives, like platinums (never!) and NGK copper 7252 (yeah!). Due for replacement, and I'm considering the NGKs. Any opinions? Thanks; Don

I was planning on running either the Bosch-Platinum+4 or the Bosch-Platinum Plus.

I plan on running e85 and figured I need these spark plugs. Am I wrong in this assumption? Why is copper better for these stroker engines?

[fedrusion]

I have always been a fan of NGK's, however I havent tooned up my chero yet since I bought it, and am running autolite platinums in my grand in my wife's grand chero.

[John]

I work under the thought that the large copper core plugs provide better heat conductance. I run a higher compression than many and you also note I listed a colder heat range plug. One of my tools to prevent ping.
John

[oletshot]

I just can't get myself to spend up to $10 a plug(cheap bastard) when I have options. NGK has always been a favorite of mine in my baots and jetskis (2 strokes). I would have no reservations using them in my stroker.

[Cheromaniac]

Hesco recommends the traditional OEM Champion copper core RC12LYC for my 4.6L stroker.

Hesco are right and those are the plugs I have in my stroker.

[Comanche91]

Hesco recommends the traditional OEM Champion copper core RC12LYC for my 4.6L stroker.

Hesco are right and those are the plugs I have in my stroker.

Damn, I screwed up my original post. Hesco recommends the Champ RC9YC, not the hotter RC12s. I've been running the RC9s for about three years now, but when I pull a couple at intervals for the old eyeball test, they look more sooty black than the ideal golden tan color. No heavy deposits or fouling, but not ideal. I've also fooled with my adj. MAP and adj. fuel pressure regulator, and monitor with a wide band A/F meter, but they still look too black. I'm thinking the RC9s may be too cold, and have recently stuck in a set on NGK 7252s about 200 miles ago, which equate to Champion RC12LYC. I'll be pulling a couple of these tomorrow to do the color check, but the engine seems to idle smoother, and I have no pinging (93 octane). But too hot a plug is much worse than too cold, and the best way to tell AFAIK is to periodically check the color. What I'm looking for is the ideal compromise between performance and mileage. Have been averaging 15 in town, 19 highway w. the AW4, 4.11 gears and 31" tires.

[John]

Afraid too many people do not read plugs correctly, I will post this link as a very good beginners text on learning this arcane art form. I really do find the RC9's right on for my build, don't know about yours. http://www.dragstuff.com/techarticles/r ... plugs.html
John

[Comanche91]

Thanks John - good read. I'm far from an expert reading plugs. My engine is running stock compression, .030 OB Diamond forged pistons, stock head, and is my D/D. I did have a recent dyno at Hesco run about two years after my build because of some exhaust mods I did, and the numbers went up approx. 15% across the RPM range. Peak torque and HP dropped about 300RPM compared to the original dyno readings, but I figure this is okay for a D/D. But the plugs now are a bit blacker, and the MAP input voltage and FP PSI settings are still very close to the stock settings. So I'm trying a hotter plug as short experiment to maybe help mileage which has dropped maybe 1-2 MPG. I have no problem going back to the RC9s, or maybe an RC11 if available from Champion. Very much appreciate your comments; Don

[John]

You are ahead of the pack just by looking and trying different plugs, too many do not. Just read them and go by what you see, but you must know what to look for and which range of motor operation you are evaluating. The last read/evaluation I performed was a under load wot. There is a high angle, mile long mountain road near here. WOT from a standing stop at the bottom, turn key off and lock it up at the top, had the plug wrench waiting in my lap. Got just a little work with timing to do.....
John

[Comanche91]

Hesco recommends the traditional OEM Champion copper core RC12LYC for my 4.6L stroker. I have heard mixed reviews of alternatives, like platinums (never!) and NGK copper 7252 (yeah!). Due for replacement, and I'm considering the NGKs. Any opinions? Thanks; Don

Well, ran the NGK 7252s for about 200 miles; definitely too hot. They looked about like the below. Not too bad, but a bit hot. Besides, the extended reach made me nervous



The original Champion RC9YCs looked more like this:



So I compromised by going up one heat range to Champion RC10YC4. The 4 means they need a bigger gap (from .035 to .042) which I run anyhow with the Accel coil. These I think are the ideal plug for my engine and driving style and give an excellent idle and correct color after another 200 miles (including some long grades under WOT):



The corner AutismZone and others do not carry the RC10s, but they can be had at Rock Auto.

[John]

Looks like a promising plug for you, are you using a fuel additive? The plug if read hot can tell you some important things about timing, The electrode strap is your friend. I really am glad to read your reference to driving style, most do not factor this in when designing a motor, or evaluating one.
John

[Comanche91]

Looks like a promising plug for you, are you using a fuel additive? The plug if read hot can tell you some important things about timing, The electrode strap is your friend. I really am glad to read your reference to driving style, most do not factor this in when designing a motor, or evaluating one. John

No fuel additives John although I do always use at least 93 octane (preferrably BP, the old Amoco white HT, also recommended by Hesco). I am close to Hesco, and return occasionally for a dyno run whenever I make any major mods to see their effect. My stroker is over three years old, and is putting out about 15% more HP and torque than the original build, and getting better mileage, mainly due to exhaust, fuel pressure and ignition mods. I think I'm pretty well dialed in now for another three years.

[FrankZ]

I run Bosch Platinum 4's. I tried the xtock Champions and got alot of noise on my stereo and CB...weird but true.