Quote:
Originally Posted by X-TECH MAN
The 69,70, 71 Street Hemi had 150 lbs on the seat and 320 open pressure specs. I have my old NHRA/IHRA engine spec book right in front of me as I type this. The 68 Street Hemi had 131 lbs on the seat and 280 open. The 66-67 Street Hemis had dual springs with the rating of 114 lbs outer and 53 lbs for the inner spring on the seat with 189 lbs outer seat pressure and 96 lbs for the inner open pressures with solid lifters.The 68 and 69s had solid lifters also while the 70, 71s had hyd. lifters. The 68-71 had single springs with a damper. This was good for 7000 RPM operation. The street Hemis with an OEM oiling sytems and pans dont take to kindly to 8200+ RPM shift points for very long. I would think most would be OK with 150 lbs seat pressure and about 320 to 350 lbs open pressures unless they are running a cam with square lobes on it. The 440 six pack had a 150/320 lb pressure spec also in 1969.
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I thought it was 180 on the seat. The memory is the second thing to go LOL.
I know it was critical. We would set up a motor with stock valve springs put it together and reve it in to 7500 a couple of times. Then pull the heads and change the valves and springs. It was legal to put notches in the piston as long as the motor did it not the machine shop.
PS we shifted at 7200 when we were trying to go fast. The only time the motor would go any higher was in the water (once in a while)