Hi Compression Head Plug Gap Setting

[Ray A from PA]

Is the plug gap setting on hi compression head the same as stock head (.035)?

 

[glenn in camino]

With a Thomas 7-1 head, will more gap or less gap keep the plugs cleaner?

 

[Tom Wesenberg]

Higher compression makes the plug require more volts to fire. The wider the gap the higher the volts required to fire. The higher the volts, the tougher it is on the coil. If you don't have a miss when flooring it going up a hill you should be fine.

I don't see where plug gap would have any effect on how clean the plug stays, as long as the plug doesn't missfire. Ford changed the plug gap a few times from .025" to .035" and I didn't notice any change trying different gaps. I'm just using the stock head and my well worn engine has 50# on each of the cylinders.

Modern cars have large gaps becasue they run leaner, and a leaner mixture is easier to ignite with a larger plug gap. Plus the modern cars have high energy ignition systems with probably at least twice the zap of the Model A.

 

[Ray A from PA]

What if you have a miss going up hill?

 

[Jim Baskin III Pa.]

Ray I have a 6.1 head that I run champion W18 gaped at 35 thousands.The plugs have a nice gray color.

 

[Tom Wesenberg]

What if you have a miss going up hill?

Then make sure the gap is correct for the points at .020 and try setting the plug gap a bit smaller.

 

[rally 1]

I'm running a Lion head at 8:1. Use a MSD-6A ignition triggered by a Mallory single point distributer. AC R44xls at .045
MSD box, major improvement in ignition quality.

Ken

 

[Ray A from PA]

Thanks, I will give it a shot and post my results.

 

[Ray A from PA]

Point gap .020 set plug gap to .030 and it runs better. Thanks for the help.