spark plugs to use

lookin for reccomedations on what spark plug to use, its a 552 with ford racing scj heads all I can find is that they use motorcraft agsp series plugs, any help on where to start is appreciated

Comp. ratio...rpm & application please?

its a pump gas deal 10.25 compression prolly around 6200 shift point at most this is a motor you spec's me a cam for a few months ago lem flat tappet 643/634 lift 260/263 I think

AR-3923 should work.

fordmonsta wrote:its a pump gas deal 10.25 compression prolly around 6200 shift point at most this is a motor you spec's me a cam for a few months ago lem flat tappet 643/634 lift 260/263 I think

use to use the AR3923 but was changing when using nitrous to a AR3934 then try using the 3934 on the streets it performs very well and also runs well at the track motor or nitrous... also who's cam is that

thanks for the help, that's is a lem evans spec'd cam I think I may have typed it wrong its a 260/263 at .050 and 640/643 lift solid flat tappet