Valve spring pressure

[Ian Hill]

I run a 350 crate engine in IHRA with a hydraulic flat tappet cam shaft and lifter set. i ran regular style valve springs last year and ran the engine past the finish line to check top end rpm limits. the engine pulled no problem to 7400 rpm. Normally i was crossing at 7100. All this while running a 4.88 rear gear set and true hydraulic lifters. Now i have gone to the solid style hydraulic lifter (call it what you will), bee hive valve springs and lighter weight retainers. I put a set of 5.13's in the rear and can only pull 7200. i am running out of steam about 80-100 feet from the finish line. i have the valve springs setup for 125 lbs at the seat and 320 over the nose. i also was down 6 pounds of tire pressure from where i normally race as i thought the track was marginal.

i know that pumping up the tires will make them grow in diameter, but it will also reduce rolling resistance to the tune of almost 2 mph and .005-.007 as tested last year. i still have 30 pounds to put into the car which also will reduce top end rpm. i am at a loss for what to do to help the rpm situation without going back to the 4.88's other than shimming the valve springs for more pressure. What is normal, what is too much valve spring pressure on a hydraulic cam shaft?

thanks
Ian