New motor won't run

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Please could somebody tell me what to check next. My new motor is
a stroker, 383 LE 2 heads /w custom cam. I 've checked everything
possible. Timing is dot to dot. 12oclock crank sprocket, 6oclock timing
sprocket. All valves zero lashed. There is a popping coming out of the
intake. Won't idle I was told by my builder that the cam was on point
for the degreed' intake centerline. help Help HELP HELP.............

P.s. iT'S A LT1