Originally Posted by
tpichevelle
Another update:
One night coming home I noticed it was pitch black dark so I left the garage door closed and used the opportunity to check my spark plug wires for arcs. My wires were generic, spiral wound, 5 years old, and looked like new. With the engine running I lifted the hood under the moonless night and no lights outside made it easy to see arcs. I saw corona on the spark plug porcelain between the boot and spark plug base. I'd never seen this before. There were also a few arcs from wires to the engine. The wire arcs definitely indicated electrically worn wires. So I bought a new set.
A few weeks later replaced my wires and did the same test. No more arcs from wires and the engine ran a little better. However, I still had corona on all plugs.
I pulled the plugs and couldn't find anything wrong. I figures maybe the .045 gap was stressing the wires by requiring higher voltage to initiate the jump. I lowered the gap to .040. The car idled a little smoother and there was less intense corona. I lowered the gap to .035 the same as a 72 chevelle spec, corona gone. The car idles smooth and has more power at full throttle.
I did some research and found:
1. Racers gap at .035 or less. As compression goes up, it's harder to jump the gap so the voltage has to go higher or the gap smaller. Higher voltage stresses the ignition components so gap has to decrease. At 10:1, gap has to be no more than .035, at 11:1 .030, and 12:1 .025. Racers experiment with this and often are less than .035. I have 9.7:1.
2. Racers file their ground straps and plug base to eliminate corners. Corners have less heat dissipation and are first to glow red hot under load causing detonation. I filed the base corner, the ground strap corners and made the ground strap end spherical. I noticed a difference but I can't say it made lots of power, hard to describe.
3. I looked at several old sets of plugs and found: my Autolite irridiums have sharp cornered ground straps, I filed these above. Champions have sharp corners. AC has a bulged side on the ground strap reducing the ground strap corner.
4. A few weeks later I read an article claiming Platinum is a catalyst for the combustion process and will help the burn initiate.
So, I bought a set of AC double platinum plugs, rounded all the corners, and gaped at .035. The car starts, idles, and pulls the best with this plug setup.
Let me know if anyone else has similar results.
Happy sparking
Reply With Quote
Bookmarks