Okay the guy that assembled my engine recommended i use bosch platinum plugs. The johnny on the spot at AutoZone said that i should use a copper plug. he said that the platinum was too hot for older engines. WTF.

I am using the stock heads (with a lot of work done to them) and a complete MSD Ign. set up on my 289. wieand intake and holley 670cfm

I went ahead with Autolite Platinums. Nobody there could recommend a proper gap. i thinking about .0035.

What is the consensis on the Autolite plug and a good gaping.

 

Autolite coppers are good plugs. The platinums do tend to be too hot for performance on some domestic V8's, especially in an iron head, but I doubt your cylinder pressure is all that high, so it may not matter. As far as a gap, if you have electronic ignition with a CD box then you'll prolly want to gap in the .045-.055 range.

 

i would listen to your engine builder, not the monkeys at auto zoo

 

i should be running 9.5 to 1

 

With the MSD setup you should be fine running a .045" gap (stock was .035"). I don't think you'll have any problem with platinum plugs, as long as they're the proper heat range (AP45's). I've run them in my 331with 9.3:1 CR and they work just fine. The platinums will last longer than coppers, but don't expect any extra performance out of them.

 

Sweet. there gapped and in. now if i could just resolve my throwout bearing situation i can drop in the power plant. i dont know if i can use the staock t5 t bearing with a centerforce clutch

 

I prefer to use copper resistor core autolite plugs.

 

Copper resistor core Autolites are excellent plugs. If you go to the track a lot of the guys that are running quickly use them(among others). Platinums last longer, but the copper cores conduct heat and resist fouling better. Platinums are fine with the right heat range(true of any plug) in a mild application where you want the plugs to last, but the coppers are better for a performance application.