valve spring pressure discussion
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From: mansfield ohio
valve spring pressure discussion I was talking to a cam manufacturer (not a mainstream manufacturer) this week and we had a discussion on valve spring tension. His contension was that I needed a spring that had 160# (or more) on the seat but less that 400# open at .635. In fact he said the mid to low 300# range was ideal. His Idea was the lifter would tend to compress on the tip of the lobe and the weak seat pressure would allow the valve to bounce. I am currently using comp 921 140# measures at the seat (new) calculates out to 399# at full lift. I dont think any of the mainstream springs that most are using in LS1 meet the criteria he is talking about. the springs he advocated to me are a larger diameter and require machine work to most heads. My heads already have the machine work done to them and in fact I already have a set of titanium retainers that will work on these springs laying around. I quess I wondered what others thought about high seat low pressure at high lift springs? 
That's basically correct, though oil itself does not compress, the lifter plunger can if certain conditions are met.
Heavier valves and faster closing rates require more seat pressure to control, but conical design springs can get away with a little less pressure.
I like the conicals, but a lot of people like dual springs because they will also meet the specs you are looking for.
IMO, with high lift cams like you're talking about, it's best to go ahead and machine the spring pockets deeper and wider to give you more options for springs, and keep you further from binding whatever spring you choose.
Heavier valves and faster closing rates require more seat pressure to control, but conical design springs can get away with a little less pressure.
I like the conicals, but a lot of people like dual springs because they will also meet the specs you are looking for.
IMO, with high lift cams like you're talking about, it's best to go ahead and machine the spring pockets deeper and wider to give you more options for springs, and keep you further from binding whatever spring you choose.
