Cam and valvetrain longevity....??? low duration high lift...
10-04-2016, 07:05 PM
#1161
Platinum Member
Platinum Member
[QUOTE=MILD THUNDER;4488269]From crane cams. Thoughts on this ? I looked up the cam card on the "651" crane cam. Their recommended seat pressure is 132lbs, open pressure, 413 lbs.
[I]3) HYDRAULIC ROLLER CAMS require higher spring seat pressures to control the heavier roller tappets and the more aggressive opening and closing rates available to roller cam profiles.
a. Small Block applications: 120
My thoughts are you need more spring pressure for when the lifter goes over the nose. The oil pressure will cause it to pump the valve open and cause the valve not to seat and or the valve will be forced to seat from cylinder pressure and cause your parts to get beat up.
[I]3) HYDRAULIC ROLLER CAMS require higher spring seat pressures to control the heavier roller tappets and the more aggressive opening and closing rates available to roller cam profiles.
a. Small Block applications: 120
My thoughts are you need more spring pressure for when the lifter goes over the nose. The oil pressure will cause it to pump the valve open and cause the valve not to seat and or the valve will be forced to seat from cylinder pressure and cause your parts to get beat up.
10-04-2016, 07:14 PM
#1163
Registered
not dynoed. But went from 540s with 651 cams to the 605s with bigger cams any better intakes. not intercooled, boost with 540s and 8.4:1 compression was 7psi. 605s tried 7.5:1 compression and the highest boost was 10psi. Boat was faster but not by that much. Then I moved the compression to 8.2:1 and 8 psi. and reground the cam a little smaller. This setup ran better past 5000rpm. This year I pulled the reground cams and went to different manufacturer cam and it runs well so far. The motors stayed in the boat this fall.
10-04-2016, 07:28 PM
#1165
Registered
I think Reher Morisson's statement here, applies to offshore marine applications . We aren't drag racing these boats.
In my experience, an extremely smooth profile is unlikely to win drag races. It might be suitable for a NASCAR stock car engine or an endurance racing application, but a cam usually needs to move the valves more aggressively to win on the drag strip. We don’t race for 500 miles, so our cams and valvetrains can be closer to the edge
In my experience, an extremely smooth profile is unlikely to win drag races. It might be suitable for a NASCAR stock car engine or an endurance racing application, but a cam usually needs to move the valves more aggressively to win on the drag strip. We don’t race for 500 miles, so our cams and valvetrains can be closer to the edge
10-04-2016, 07:35 PM
#1166
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Are bobs cams designed for a .700 lifter wheel, a .750 lifter wheel, or what? Does anyone know the answer to that? Or has that ever been a question? While a minute change, the lifter wheel diameter, does play a role in the actual cam timing. Not a ton, but, I mean we are talking about super secret squirrel custom cams, I would think that would be a consideration. The johnson lifter has a .700 wheel, morels, PBM, lunati, howards, upper end hyd rollers use a .750 wheel.
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10-04-2016, 07:46 PM
#1168
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