CGGorman

Anybody running gap that big? I was picking throughy MSD Digital 6 owners manual looking for a start retard setting and ran across a gap chart. For my compression (<10.5:1), it recommends a gap of .050"-.060".

I'm currently at .045" and it seems to run just fine. What would be the advantage of increasing my gap another .010"?

MsVetteMan

lars

The problem with running a gap that big on a higher compression engine is that the resistance across the plug gap becomes very high. The MSD has the voltage and power to blow a spark across that gap, but you tend to run into other ignition system components that do not have the dielectric (insulating) capability to handle it, so you get arcing out of plug wires, cross firing and grounding inside the cap, and other insulation breakdown problems. By reducing the gap slightly, you assure that the spark stays at the plug, where it belongs, and that you do not produce misfiring and arcing at other component levels. For high performance use, we've been running gaps of .035 (and up to .045 on street engines), but nothing bigger for the above noted reasons.

gkull

Faster flame travel = marginal HP gains. That's why I run the 10.2 mm Taylor Pro wires. I had my motor running nice out to .070 But just as lar's pointed out you are on the verge of arcing. Then you have to run Plat or IRD plugs because it with just vaporizes the center electrode.

I just run .045-.050 and big wires and don't worry about it with my autolite Plat plugs. I'd like to get the Bosche plat 4 tips for these heads. 3/4 deep reach for angle plug heads - No more indexing the plugs!