Is .035-.038 the correct gap for a stock head LT1 with spray? I have mine gapped at .038 and put them in the car and it now has a slight low rpm stumble between 1200-1700rpm.

 

I ran mine at .035

 

Im not sure whats up with your car. But .035 sounds right for a n2o LT1.

 

I have an ls1 but I run tr6's at .040 with no miss/ stumble problems.

 

Your gap is correct. The 6's are a cold plug, that makes low rpm operation less smooth. So really you just learn to live with it or go with 55's and pull some timing or run it a little richer on the spray. I have 6's at .035 and longevity has been outstanding.

 

Thanks everybody, I put a new set of wires in and it fixed the low rpm stumble.

 

I was just going to say, check the wires and other electrical items. Many times it some stupid like a battery cable or something along those lines thats the cause of many issues.