Which plugs to use???

[86camo1ton]

I am getting my stroker back from the machine shop tomorrow and I had him assemble the long block so he could check all the clearances. My motor should go back in and I should be driving by this weekend. Now for the question below is the motor I built (cut and pasted from http://jeep4.0performance.4mg.com/stroker.html ) I am using a clifford intake and quickfuel holley carb ( I know you are all think why didn't he use the fuel injection but I am just a carb guy at heart) So what Spark plugs should I use and what gap. I am also using a GM HEI distributor . I highlighted in red what has been suggested but I just wanted to hear the options and what gap on these plugs Any suggestions would be greatly appreciated. I also had the heads ported (1993 4.0)

Thanks Jeff


[COLOR="Red"]Autolite Platinum Pro Spark Plugs
Part no. APP985[/COLOR]


4.5L Low-buck simple stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Speed Pro H825CP +0.030" bore pistons
9.6:1 CR
Mopar/Victor 0.045" head gasket
0.083" quench height*
CompCams #68-231-4 206/214 degree camshaft
Ported HO 1.91"/1.50" cylinder head
265hp @ 4900rpm, 325lbft @ 3500rpm

[aston]

I installed a 4.6L Golen Stroker a couple of months ago. Initially the detonation was very bad so I retarded the ignition 2 degrees, it was still there so I want another 2. Still detonating but less severe.

I went from autolite 985 plugs to 3923 and the detonation is still detectable.

I guess I'll be calling Golen again :mad:

I am beginning to wonder why I am pissing around with such a well developed engine

Here's a couple of heat range charts to help.

http://www.cvproducts.com/cv/technical/heat.aspx