Bog or delay under wot?

[Olive1970]

I have had this issue with my newer engine that I put in. If I put the gas to the floor it will bog or not have the same response as above say 3500rpms or so? After that it will come alive and just wrap the rpms up, where as before 3500rpm the delay is obvious on the tach.

The truck has HEI, Holley 650 spreadbore, built TH350 with 2200 stall converter.

The engine is: 350 bored 40 over, flat top pistons, 1.94/1.60 valves, double roller, weiand intake, z28 springs, bunch of new factory parts, and a pretty rough cam int exh
dur@.050 234 244
valve lift .488 .510
lobe sep 107 117

I am thinking this is a distributor advance issue? Maybe time to swap springs or make some other mods to the advance? Or time for a different dist?

Thanks all, spring is coming