BBC plug life

[Bob Verwold]

Originally Posted by Ron Gusack

I ran the B9ES plugs then went to the 7's and just put the 5's in on Friday. I cross the line at about 7200 in good air. Will a 6AL work at that RPM and compression?

Don't know if this is comparable or not but my small block (421, 14 to 1 on c-12) runs on a 6AL with all MSD parts. Dist, crank trigger,box, wires and coil and my plugs were in for about 2 1/2 years before the motor had a miss, changed plugs and they have been in half of last year and all this and still working good.I'm using champion RC 59 YC plugs gaped at .035. And I do go over 7200 rpm.