Quote:
Originally Posted by madmaxx
Shoot at 150/375 spring pressure my valves floated at 5300 rpm with the aforementioned cam. It did have AFR 205 heads and I assume their stock AFR components.
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Max: on my current 331 stroker with a hydraulic roller cam...quoting these numbers from memory,so they are not exact, my notes are not handy right now..
lift is somewhere around 525 to 550, duration is only in the mid 270 degrees range (I don't care for "lopy" cams) ,I have the spring pressure set at 150 on the seat, don't remember what the open pressure is.....Stock Ford OEM small block hydraulic roller lifters,good 1.6 roller rockers (don't remember the brand name) and I've turned this engine 6500 rpms with no hint of valve float....rev limiter is at 6250 right now........I'd bet the rent it would go to 7000 before any hint of valve float.....
Very old ,third hand,swap meet set of Edlebrock Performer alum. heads,but they have had "some" work done on them.....I don't remember what brand/size valve springs I put on these heads,but they were a really good set..
I think the combination of valve springs/rocker arms/lifters and the valve train geometry have a lot to do with what rpm the valves will float at.....
BTW: Mud racing is a big thing down here for the last few years and seems to be growing....One top racer who is a personal friend, has a machine shop/engine building service and long time racer....they are turning 460 cu in big block Ford engines 8,000 rpms, average run last about 25 seconds..rules mandate OEM cast iron heads,but you can do pretty much anything to them other than change the original valve angle and they must run a hydraulic flat tappet cam/hydraulic flat tappet lifters and pull 14 inches of manifold vacuum at 1,000 rpms.....
How they do it without valve float,I have no idea, but they do it all day long......
David