Spark Plugs for Slant Six?

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Plugs don't look bad. You'd probably have better driveability with the NGK ZFR5Ns (remember, no ring gaskets).

Mopar electronic ignition is better than breaker points, but you can do a whole lot better and an upgrade would pay benefits in how the car runs. Whether or not you upgrade, read and follow the suggestions in this long (but worthwhile) thread.

Your plug gaps are too small even for the relatively weak Mopar electronic ignition. If you stay with that ignition, run 0.035".

93-octane gasoline is not "the best rating". It is not better than lower octane grades, just different in exactly one way: it's more resistant to ping (preignition). If the engine doesn't ping on mid-test or regular, there is no advantage to high-test. The only exception is if you live one of the few places where you can still buy one grade of gasoline without ethanol in it, and that grade is the highest octane offered.

I would like to run what I have so I can drive the car. Then upgrade her....

So you reckon even with that stupid big cam, .0035 is good to go?
Should I add any timing? (I have not established that baseline yet-though I probably should :rolleyes:)

Thank you kindly for yer insight, Dan. I am much obliged. :thumbsup:
 
I'm trying to imagine how and why a big cam would want small plug gaps. I'm failing.

Ignition timing (basic and advance curves) will have to be a matter of tuning and driving, tuning and driving, tuning and driving.
 
I'm trying to imagine how and why a big cam would want small plug gaps. I'm failing.

Ignition timing (basic and advance curves) will have to be a matter of tuning and driving, tuning and driving, tuning and driving.

Once she is back on the ground, I will fiddle with the plugs and the timing. Ill probably go with .030 to start (cuz it was running ok before with that gap) and adjust from there. I will certainly get the NGK plugs you recommended though.

Thank you Dan
 
The Chrysler spec for electronic AND points ignition is .035.
I think I remember SSD saying you can go to .040 or .045 with HEI because of the hotter spark.
Why do you want to go smaller at .030?
 
The Chrysler spec for electronic AND points ignition is .035.
I think I remember SSD saying you can go to .040 or .045 with HEI because of the hotter spark.
Why do you want to go smaller at .030?

Thank you KK.

Dont get me wrong, im not trying to fly in the face of great advice, but I have a lot of unknowns with this car yet and do not want to change too many things at once and chase muh tail. Easy enough to change em to .035 once she's back on the ground and running.
 
I have a 68' 225 slant 6, with an MSD cd box with electric distributer.

Should I also be running NGK ZFR5N?

If so, what gap?

Thanks!
 
I just pulled ACDelco R45XLS out while trying to hunt down an overheating issue. (That's a whole other animal)
 
While I have never been "on the other side of the Atlantic" from this side good old Champions have always served me well
 
Plugs don't look bad. You'd probably have better driveability with the NGK ZFR5Ns (remember, no ring gaskets).

Mopar electronic ignition is better than breaker points, but you can do a whole lot better and an upgrade would pay benefits in how the car runs. Whether or not you upgrade, read and follow the suggestions in this long (but worthwhile) thread.

Your plug gaps are too small even for the relatively weak Mopar electronic ignition. If you stay with that ignition, run 0.035".

93-octane gasoline is not "the best rating". It is not better than lower octane grades, just different in exactly one way: it's more resistant to ping (preignition). If the engine doesn't ping on mid-test or regular, there is no advantage to high-test. The only exception is if you live one of the few places where you can still buy one grade of gasoline without ethanol in it, and that grade is the highest octane offered.
I just read somewhere that with an MSD box I should be running .06 gap in plugs. This correct? Also same NGK plugs ZFR5Ns for my 225 slant I assume? (Washers removed of course)
 
Headed out to a small weekly parking lot meet this AM. Shifted into overdrive @40 mph and experienced what felt like a U-joint failure! Turned around and slowly headed home, no vibesas I worked gently through the gears. When lugging the engine I again got the vibe, like a major spark miss. Got home, checked the wires, #2 plug wire loose on the plug, snugged it, same issue when short shifting.
Hmm...vacuun leak? Nope dizzy & PCV hoses intact, not leaking.
Note: Car has a'66 motor, and I've only put about 200 miles on it. Dizzy is stock vacuum advance, has the pertronix points eleminator in it.
Carb was recently rebuilt, Used the thick base gasket, nuts took about 3/4 turn to snug. Bingo problem solved.
Now how this relates to this thread, checking the plugs I found NGK GR4's, and they still have the washers!
All six plugs are a nice tan color. no wear on the electrodes, gonna pull the washers and get new drool tube gaskets.
Everyplace I look this is this recommended plug, I understand it is 1 heat range higher, but the tip color is not indicating a lean condition. No oil burning or fouling.
Curious if anyone has had an issue running these.
 
I just read somewhere that with an MSD box I should be running .06 gap in plugs. This correct?

No, that would be a bad idea. Run 0.040" to 0.045" and make certain you're using good high-end plug wires and a good cap and rotor, which is difficult; read and follow the suggestions in this long (but worthwhile) thread.

(Also, MSD is a great way to get stuck somewhere due to ignition failure, someday, without warning. You're much better off, both result-wise and money-wise, doing the HEI upgrade instead.)
 
Spark plugs for a slant 6? The Champion number is tattooed on her arm. She's a turbo slant gal I met at Carlisle a couple years ago.

Gary.jpg
 
No, that would be a bad idea. Run 0.040" to 0.045" and make certain you're using good high-end plug wires and a good cap and rotor, which is difficult; read and follow the suggestions in this long (but worthwhile) thread.

(Also, MSD is a great way to get stuck somewhere due to ignition failure, someday, without warning. You're much better off, both result-wise and money-wise, doing the HEI upgrade instead.)

Thanks for the info.

I'm going to stick with it because it's already on the car and functioning fine. I know adding more technology adds failure points but thats ok. I'm also running a super sniper EFI which I get told all the time I shouldn't have complicated things.
 
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