I have a 1997 5.7 GIPLKDCE that had the block replaced and switched to a carburetor. So I am trying to understand my options for spark plugs. According to VP, the original engine needs 3851861, which I cross-referenced to Champion RV15YC4, and this is what VP mechanic installed few years back. NGK suggests 6630 UR4 as a replacement for VP 3851861. Looking at other NGK options I see 4323 BR6FS that is recommended for GM small block 5.7. I see that VP-recommended plug is much hotter. What is the wisdom there? Should I look into colder plugs given that the engine was switched to a carb? Any recommendations? The engine started missing heavily on cold starts (runs fine once it warms up), so, I am contemplating a new set of spark plugs...
