I wanted to tell everyone about my experience with spark plugs.

I have tried NGK, Champion, Accel, AC Delco, and Autolite plugs in my 70 442 with a 455.

Out of all the plugs tried, the Autolite Platinum #85 worked the best. The engine idled and ran best with them.

The AC Delco RapidFire plugs also worked well, but are more expensive.

My ignition combo:

Factory distributor recurved, with a Pertronix Ignitor

Pertronix coil

Taylor wires

Blur Streak car and rotor

Autolite platinum plugs

Works great.

 

Do you know if these #85's will work with Edelbrock aluminum heads? Have the same coil and pertronics as you. Thinking of going to an MSD box. Any thoughts?

 

I am not sure, but I think Edelbrock heads take a different plug.

 

Edelbrock heads require a 14mm x 3/4" reach gasketed spark plug and depending on application the heat range will vary from Champion RC-9YC to RC-14YC or equivalent. RC-12YC is recommended for street use

The MDS Box will give you a hotter spark and you will have to increase the plug gap (the MDS directions give you the perimeters for the gap

 

So the plugs I need are a metric thread? Or the Champion RC-12YC is what I need? I have Accel in there now that I got when I bought the heads but am not happy with them.

 

Correct on the thread. They do not have to be champion, you can cross reference to any brand. If its a street driver the just go with the equivalent to the champion RC-12YC in your prefered brand