| I have my cam on order, and I have my recommended spring specs (145-150lbs & 350-360lbs). I have my springs chosen (“ISKY” 6105-SP) and now I am trying to dial in my installed height (on paper, as I will check my actual lifts after the cam install). I was told by the cam company that the new valve springs may lose apx 10% of its pressure during the break-in procedure (I will be removing the inner springs). If so, do I just add 10% onto my recommended seat/nose pressures and match up the installed height? If so, my new pressure ranges are 159-165lbs & 385-396lbs before loss. The three previous cams that I installed in this block, I just aimed for the recommended spring pressures and never considered the 10% loss detail. This time, I want to make sure before I start. Thanks |
Valve Spring Pressure Loss After Break-In
- Thread starter YO7_A66
- Start date
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Scody21
Just send it
your over thinking it. Just send them.
Professor Fate
Push the button, Max...
The key word here is "MAY". Not "will".
Break it in, reinstall the inners, and see what you've got. Chances are you won't have to dink around with them at all.
Newbomb Turk
Well-Known Member
Break it in and then verify the spring load. Shim accordingly.
I ain't sure I'd even shim to get 10% back. Maybe if I was racin for $$$ I might.
Newbomb Turk
Well-Known Member
Yeah, 10% (if they actually lose that much) is only 14-16 pounds so it’s not that critical.
Of course, being the anal retentive simple minded fool I am, I’d measure the springs after break in or maybe after dyno time or several hundred miles and shim them.
Its a sickness…
I don't know. I wouldn't call it a sickness....maybe just a "I wanna know" kinda thing. I'm just too dang lazy. Long as it still runs good, that's all I care about. lol
The 14-16lbs reference puts me in or knocks me out of the 145-150 & the 350-360 ranges. I know that I am being anal about it, but if I shim for the ranges and the springs do lose tension, then I am under the range.
If I compensate for the 10% loss and they don't lose, then I am over the ranges recommended by the cam guy.
GRRR: I don't want to invest into a spring checker.
Thanks!!
Newbomb Turk
Well-Known Member
Here‘s the deal with that. If you lose 16 pounds of spring load and your valve train goes out of control you should probably look at lighter valves, lighter retainers, bigger stiffer pushrods…stuff like that.
That is the worst issue with any FT cam. You can’t add spring load to get rpm. So you have to make other parts lighter and/or stiffer.
Im all for shimming them as I said above, but not because I’d be worried about 16 pounds (if they lose that much) but because I get mental over things like that (lol it sounds like you may be of the same mentality lol) so you have to make yourself happy.
And if that means shimming them back up, I wouldn’t waste another second thinking about it, I’d just do it.
My less than .02 worth of opinion.
I will plan on having enough spring/shims to be able to hit the upper range that I was given as a minimum, and maybe stay slightly higher just in case the springs lose a little after a few heat cycles.
Thanks everyone!
I ran Isky Springs on our 340 Stockers (#3105)
for several decades. If the quality is still
the same = I set them at 165 on the seat and
seldom saw them below 158 to 160 when
I freshened them up after 50 runs.
for several decades. If the quality is still
the same = I set them at 165 on the seat and
seldom saw them below 158 to 160 when
I freshened them up after 50 runs.
furrystump
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I haven’t used Isky springs, but I would install them and run them. Check them after a bit to see if they gave up anything. If they did I would shim them. I run PAC’s,never gave up enough to worry about. Swapped them last year because I’m a worry wart.
I am now looking into a couple of the Comp springs (985 & 925) instead of the Isky's (6105SP & 8005SP/8005A) that I have been looking up. The Iskys are taller springs and they are showing .140" or more clearance to coil bind at my max lift range. I believe that I can get the two Comps mentioned into the .070"-.090" range with this new setup.
furrystump
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I’m over .100 from coil bind and it’s not ideal. I have run it like this for many years. Solid flat tappet not a ton of lift, but would like it closer to settle the spring down. No indication it is surging. I ran a comp spring years ago, no issues. Valve train is a place we’re you can’t really “check” things enough. Not a place to save on costs. The cost of a mistake can be catastrophic.
Check out Beehive or Conical Springs. Require 10-20% less tension, virtually eliminates the possibility of spring surge in the operating rpm range.............& valve train will last longer.
Comp #26918 might be a good choice.
Comp #26918 might be a good choice.
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