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My valve spring have about a dozen passes on them and, as part of my maintenance, I check opening pressure. new they checked in at 300 lbs. Now they check at 260-280 lbs. At what point should I change them?
540 BBC, AFR 357 heads, solid roller cam 806/765 lift
 

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My valve spring have about a dozen passes on them and, as part of my maintenance, I check opening pressure. new they checked in at 300 lbs. Now they check at 260-280 lbs. At what point should I change them?
540 BBC, AFR 357 heads, solid roller cam 806/765 lift
If you have room from coil bind, put a 20 thousandth shim under each, and they’ll run quite awhile longer.
 

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My valve spring have about a dozen passes on them and, as part of my maintenance, I check opening pressure. new they checked in at 300 lbs. Now they check at 260-280 lbs. At what point should I change them?
540 BBC, AFR 357 heads, solid roller cam 806/765 lift
Valve springs will always take what I refer to as an "initial hit". Meaning that most all valve springs usually will loose a bit of pressure and then most will stabilize. There are several factors that go into changing springs. But to keep this simple for now. How far are you from coil bind? I assume when you set the heads up you set everything up knowing how far from bind that you wanted the spring to be. Also, I would never setup springs just by going off what the cam card says for max lift and or calculating everything.

Nick
 

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HP drops off like crazy if the springs have gone weak. Watch your trap mph... if it's staying consistent, I'd bet the springs are fine. I change my 540's every 2 seasons just as preventative. I've just used the same PSI spring number that the original engine builder used, and I've never even checked the pressure. I'm near PSI, so I had them check seated and open pressure of some of my old springs and they had maybe dropped off 20/30ish since new. My 540 with about a .780 lift cam runs exactly the same ET/MPH with new or 2 year old springs.

My SWAG on when you should change them... next Fall, or if you lose trap mph... whichever comes first. I take my rockers off during winter storage. That's probably not even necessary, but a habit.
 

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Discussion Starter #5
I didn't set the heads up, AFR did. The springs are rated for .850 max lift so I'm good there. Coil bind at 1.100 so I'm good there. Was just curious on what to watch . Thanks!

Valve springs will always take what I refer to as an "initial hit". Meaning that most all valve springs usually will loose a bit of pressure and then most will stabilize. There are several factors that go into changing springs. But to keep this simple for now. How far are you from coil bind? I assume when you set the heads up you set everything up knowing how far from bind that you wanted the spring to be. Also, I would never setup springs just by going off what the cam card says for max lift and or calculating everything.

Nick
 

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I didn't set the heads up, AFR did. The springs are rated for .850 max lift so I'm good there. Coil bind at 1.100 so I'm good there. Was just curious on what to watch . Thanks!
So here is my recommendation to you since AFR set your heads up. There is no way they know what your "actual" lifts are on your engine. It all had to be based of "theoretical" numbers. If you have some time to really figure out where you are at with all of this, this is what I would do. I would first set a dial indicator up on you intake spring. Leave the lash and everything just like you race it. Then measure the gross valve lift and write it down. Do the same for the exhaust as well. Now that you have your "actual" gross lift numbers you can now calculate an "ideal" installed height. You only need to know what your spring recommends for coil bind clearance. On high end drag race engines you will see coil bind clearances down to .070" and up to maybe .120". A lot of times it's a builders preference but I also wouldn't run a spring a long ways off of bind. Based off what little I know about your combination, I'd think .120" would be a good number for your application. You could go down to .100" but I don't see any need to go tighter than that. Now all that's left is the math. Lets say your actual is actually .806/.765 lift. Just take your "actual" lift plus coil bind height plus the desired coil bind clearance you want and that number is what you want your installed height to be.

INT installed height is .806 + 1.100 + .120 = 2.026 installed height
EXT is .775 + 1.100 +.120 = 1.995 installed height

You could also run the same installed height for both INT & EXT and that does give you more clearance on the exhaust side from bind. The exhaust side typically isn't as critical as the intake side is when it comes to bind clearance.

Again, the most important thing is to actually know what you "actual" lift is and not the "theoretical" lift is.

I hope that helps....

Nick
 

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What if the desired installed height equals too much installed or open pressure? On BBC Dart Pro 1 head, what would be too much installed height pressure or open pressure for a .800" bracket race cam? When I see only 4-5 threads on the intake rocker stud bosses it makes me wonder if the springs could pull the threads. Would a one piece rockers stand distribute that better than just a rocker stud? I am seeing 300#+ installed height on some of these. (Sorry if I ran of course of this thread.)
 

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What if the desired installed height equals too much installed or open pressure? On BBC Dart Pro 1 head, what would be too much installed height pressure or open pressure for a .800" bracket race cam? When I see only 4-5 threads on the intake rocker stud bosses it makes me wonder if the springs could pull the threads. Would a one piece rockers stand distribute that better than just a rocker stud? I am seeing 300#+ installed height on some of these. (Sorry if I ran of course of this thread.)
Mark,

The problem with running to much clearance to coil bind and increased install height is just the function of the spring. A lot depends on the cam profile, RPM and weight of parts. If the spring is to far away from bind, you can get an increased amount of spring surge. When that happens, you can then start to damage parts. If the open pressure is a lot more than desired, one might want to look at a different spring to better fit the application.

There is no doubt the stud mount rocker arm won't hold up as well as a shaft system. If I was running a stud rocker arm which I did years ago with my S/G car, I also ran a stud girdle. 300#'s or a bit more shouldn't over stress a stud mount system but I would recommend getting as much thread engagement as you can. 4-5 threads sure doesn't sound like much. On a 7/16-14 thread, 4 to 5 threads is only .286 to .357 worth of thread engagement. Rule of thumb is always try to get at least 1.5 times the diameter. So for a 7/16-14 stud you would want at least .656 of thread to engage and that's just a tick over 9 threads.

Nick
 

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Dart Pro1 CNC 355/365 and AFR 357/377 CNC all have only 4-5 threads left once the cnc program is finished on 2 of the ports roofs on each head. I have both, no problems yet with T&D one piece intake rocker stands. I have seen repair methods that include a pipe plug installed and tapped.Thanks for your simplification on valve set up.
 

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Dart Pro1 CNC 355/365 and AFR 357/377 CNC all have only 4-5 threads left once the cnc program is finished on 2 of the ports roofs on each head. I have both, no problems yet with T&D one piece intake rocker stands. I have seen repair methods that include a pipe plug installed and tapped.Thanks for your simplification on valve set up.
That seems crazy to only have that much thread engagement but thank goodness for the one piece stands. That has to be a big help in keeping some strength there. The pipe plug trick or method is a great way to repair things. I do use it as a last resort to a heli-coil and then a king-sert and then the pipe plug. Good luck with everything and from the sound of things. Don't go to Minnesota!!!

Nick
 
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I take my rockers off during winter storage. That's probably not even necessary, but a habit.
Always a good idea to remove rockers during extended storage periods, in my opinion . . . . . . . .
 

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If you rotate a stored engine over once a month and don't stop in same position, is that any better for valve springs that just letting it set? And lube the springs to prevent corrosion from starting.
 

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I always take my rockers off during winter to relieve spring pressure. I had 400 passes on my 603 before I replaced springs.
 

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If you rotate a stored engine over once a month and don't stop in same position, is that any better for valve springs that just letting it set? And lube the springs to prevent corrosion from starting.
I think so. I used to remove the rockers, but found, in reality, it doesn’t seem to make any real difference. Heat, and cycles are far more damaging.
 

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Always a good idea to remove rockers during extended storage periods, in my opinion . . . . . . . .
If you rotate a stored engine over once a month and don't stop in same position, is that any better for valve springs that just letting it set? And lube the springs to prevent corrosion from starting.
I think so. I used to remove the rockers, but found, in reality, it doesn’t seem to make any real difference. Heat, and cycles are far more damaging.

Here's my 2 cents worth... Like Randy said, heat and cycle time is more damaging to the valve spring. If relieving the pressure was in deed a fact to save the spring. Then I guess instead of just backing off the arm, you now need to take the spring off the engine. There's still pressure and stress even when closed right? BUT in saying that, backing the rockers off and or just taking them off can't hurt anything at all. If I had an engine that was going to sit for a long period of time, I would take the arms off but for a couple of reasons. One like I said above, it can't hurt but more importantly. I will take the plugs out and treat the walls so they don't rust. I'll put the plugs back in and with all the valves closed, my cylinder walls are now all completely sealed and preserved until I'm ready to use the engine again.

Nick
 
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And no critters inside your engine either......which reminds me...I need to fog mine again....super humid here and I'm not going out again until the weather cools off, likely late september....
 

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What lubricant do you like to use to protect cylinder walls? I have used various sprays and they seem to leave a stain where ever the piston skirt is. Do you think a stain effects the sealing of the rings? They always leak test OK. Also do you think the very bottom of the cylinder gets lube by spraying as the rings bring up the lube as rotated? And what about protecting the rest of the interior metal when storing an engine that you can't reach without the intake and oil pan off? Do you spray valve springs to protect from corrosion?
 

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What lubricant do you like to use to protect cylinder walls? I have used various sprays and they seem to leave a stain where ever the piston skirt is. Do you think a stain effects the sealing of the rings? They always leak test OK. Also do you think the very bottom of the cylinder gets lube by spraying as the rings bring up the lube as rotated? And what about protecting the rest of the interior metal when storing an engine that you can't reach without the intake and oil pan off? Do you spray valve springs to protect from corrosion?
Well, in theory, everything in the engine is already coated with oil from when it was ran. I haven't ever torn an engine down that was sitting for months and still not have a film of oil on it. As far as the cylinder walls go, there are a couple of products out there that are specifically made just for that. I can't think of the names of them right off hand but they do work. Maybe someone can chime in and say what the names of them are. I personally use Marvel Mystery Oil and feel it works well. But none of my stuff ever sits for months so I really don't know the long term affects of Marvel. I know what you are saying about the staining around the pistons skirts and I have only found that to be a cosmetic thing. I can't say that I have ever seen that stain have a detriment in performance when ran again. The springs should have a coating of oil on them from the oil and if they don't you could spray them with a light coat of WD-40 and I would think that would be fine or brush oil on them.

The one thing I use to do and have changed my ways now is when oiling the cylinders. I use to put some Marvel in a tube and then pressure shoot it in the cylinder with air. It creates a mist or fog in the cylinder to coat everything. Once I did that on all 8 cylinders, I would then spin the engine over several times and put the plugs back in again. But at times I would see a couple marks from time to time when it was real humid. It never hurt performance but it still bothered me. I then thought maybe I was defeating the purpose of oiling down the cylinders if I spin the engine afterwards and I just scrapped off everything I just coated. So now I turn the crank at 45* or anywhere that in the middle of two cylinders being at there TDC. I only do that so I have room to still put my tube in the spark plug hole. I then do the exact same thing as above on all 8 cylinders but now I don't spin the engine over. So in theory all 8 walls are coated and good to go...

Nick
 
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