Hey guys, I have a new 383 Small block chevy, 10 to 1 compression, aluminum high flow heads, roller cam shaft with .528 Intake .536 Exhaust lift, 221 Intake / 226 Exhaust duration @.050 and a 110 degree lobe separation; running a Holley 750 cfm carburator and a HEI Distributor. It has long tube headers with 2.5" dual exhaust, with Flowmaster Super 10s on it. The engine dynoed at 426 HP at 5700 rpms and 452 ft lbs of torque at 4300 rpms. The issue I'm having is that I'm running the cold racing spark plugs that it was dynoed with (Champion 792), gapped at .045", getting spark through a new HEI dizzy and sometimes during cold start I have a spark plug that will have an intermittent miss that goes away completely as soon as the engine starts to warm up.

This only happens after a few short trips in the car, where the engine doesn't get a chance to warm up all the way and doesn't get driven at cruise speeds. I'm wondering if I should step up to a little hotter spark plug, or maybe even extend the spark plug gap out a little to help with the issue.

I have a motorcycle that's the same way and you simply don't start it unless you are going to take it out long enough to warm it up completely and cruise it for a while at highway speeds. I'm just hoping that I can make the engine a little more street friendly with a little hotter plug; any suggestions or advice on the issue will be appreciated.