ZZ 502 Question

I recently dyno'd a brand new ZZ502 (complete deluxe). The only
time I was able to get the rpm's past 5200 was on the very first pull. The oil temp was 140 F on this pull. On subsequent pulls with oil temp at 150 F or greater it acted like it was experiencing valve float.

The first thing I checked was valve spring tension. According to GMPP the springs should check 140 Lb @ 1.94 inches. All springs on this engine checked 135 - 140, which I feel is acceptable.

Next the lifters were checked. One lifter would not pump up, even out of the moter submerged in a can of oil. A few others would pump up but never get really hard feeling. So, I ordered a new set of lifters and installed them. On the first pull with oil temp at 140 F everything went fine, after that it was the same as before, 5200 rpm max, on the very last pull I got 4800 rpm before the flutter symptom. All tests were with Valvoline 10 W 40 and the zero lash setting was checked by several very knowedgeable people.

anybody have any ideas on this????............pduecy.....
:mad: