colder plugs

[Aussi440]

Guys,

I have abone stock, 68 Charger, 440, 375 horse resto cam, having a little trouble with detonation if I bump the timing above 30 total.  I'm running the RJ12YC champions, is there a colder plug I can run that is available at Advance Auto or a normal shop.  Thanks Ryan

[Ghoste]

They don't have or can't get 11's?

[elacruze]

At what RPM/throttle do you have detonation? Perhaps you only need a timing curve adjustment.

[Ghoste]

Or a lean fuel curve, gas isn't what it once was either.  What are you running for a carb?
Elacruze brings up an excellent point as there could be a number of reasons for detonation.

[Aussi440]

Thanks guys,  I've tried different timing curves and springs, anywhere from all in at 2200 and up to all in at 3500,  I'm running the stock avs carb, it's an original one, the knock is all the way through the rpm range when you run it hard.

[elacruze]

Richer main jets *may* help some. My best guess is that you'll have to change cam timing, compression, or octane to put more ignition timing in it. You're just getting the best you can from the fuel you have with your build. Do you know your cranking compression?

[BSB67]

Guys,

I have abone stock, 68 Charger, 440, 375 horse resto cam, having a little trouble with detonation if I bump the timing above 30 total.  I'm running the RJ12YC champions, is there a colder plug I can run that is available at Advance Auto or a normal shop.  Thanks Ryan

How many places are you posting?

My experience is that the plug can makes a big difference especially if the one you are using is too hot.  A J12Y is a little to hot for a stock compression ratio 440.  A NGK R5670-6 or an Accel 134 would be equivalent to a J11Y.  An NGK R5670-7 would be like a J10Y, and a R5670-8 and Accel 132 would be like a J61Y.

I would recommend the R5670-7.   They will foul a little sooner but if your a gear head, you'll probably changethem before you need to anyways.  Make sure that your cooling system is perfect and run a 160 degree thermostat.  If these don't work, slow the timing curve down before you pull total timing out.

What centerline did you install the cam.  If you back it up four degrees, that will help.

[Aussi440]

My cranking compression is right around 160 for all cylinders. 

Will the NGK 5670-6 or 7's be good for everyday use?  I drive this car to and from work everyday.

Thanks Ryan

[BSB67]

My cranking compression is right around 160 for all cylinders. 

Will the NGK 5670-6 or 7's be good for everyday use?  I drive this car to and from work everyday.

Thanks Ryan

Sure.