Correct Gap for Spark Plugs
I have been reading on a couple of RV sites and there are 3 different answers. I 'm installing new plugs & wires on a Vortec 8.1 engine. My book says they should be gaped as per engine specs. I can...
Forum Discussion
falconbrother wrote:
Personally, I gap a shade small. My Suburban 5.3 calls for max of .60. I gapped at about .50. That way as it wears in it will stay around the sweet spot longer. When I changed them out they were way worn out, like .80+. As you can imagine my torque has greatly improved. The only symptom it displayed before was wanting to down shift climbing hills in OD. Now it doesn't need to (not towing). The GM V8s are really forgiving.
As a side note I bought it used and so, had no idea how long the plugs had been in there. I bought iridium plugs on Rockauto.com along with all new plug wires. Runs perfect.
Yep, I've generally found the same thing to be true. Today's COP (Coil On Plug) ignition systems are SOOOOOOO much better/stronger than those of yesteryear. In my shop days, we used oscilloscopes to read the actual plug firing voltages. Normally, it took about 12K - 16K volts to fire a properly gapped (.035") plug in a 10:1 compression distributor equipped V8. As the plug gaps grew, the firing voltage would go up until the coil couldn't take it anymore, and, under load, the plugs would begin to misfire around 30k - 40k volts. We could see/watch it happen on the scope. Properly gapped new plugs fixed it everytime. Back then, plugs were getting tired at 12K miles but would survive for much longer in lower compression, low performance engines.
Chum lee
