Cams and spring pressures
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Senior User
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From: Crownsville, MD
Cams and spring pressures
It seems pretty obvious what would happen if your spring pressure is too light for the cam you are running, but what would happen if you go with heavier springs? Would you wear off the cam lobes? Is tyhis because cams made to run higher spring pressures are made out of harder steel? Can you get away with going a little over the recommended spring pressures?
Post Fiend
Joined: Jan 2003
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From: Iowa
You probably could get away with a LITTLE over the recommendation, but there would be no benefit. The cam manufacturers make their cams to make power at a certain rpm. They recommend springs that wont float the valves up to the maximum rpm of the cam. Unless you're running a destroked race motor, there would be no benefit of going to bigger valve springs.
And yes, too large of a valve spring will wipe a lobe. You have to figure you have 1.76x the pressure on the cam lobe you have at the valve, due to the rocker arm ratio.
And yes, too large of a valve spring will wipe a lobe. You have to figure you have 1.76x the pressure on the cam lobe you have at the valve, due to the rocker arm ratio.
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Joined: Feb 2004
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From: Fort Rucker, AL
Rusty, I'm running a stock cam, soon to go to the Crane 901. I have C6 heads and going to D2's but I was going to go ahead and fit the D2's with the springs for the 901 and put them on the engine. From what you are saying, that's a bad idea.
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Senior User
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From: Crownsville, MD
Obviously, I am no expert since I started this thread asking about going over and under on spring pressures, but my guess is that a stock cam can handle the springs recommended for the 901. The springs for the 901 are pretty low pressures and may even be the same ones recommended by Crane for their OEM cams. You should check on their website to confirm this though.
My take on spring pressures is that if you are under the recommended pressure, you will have valve float at lower RPMs than the manufacturers predicted point for float. If you go over by a lot, you will wipe your cam lobes since the cam was not engineered to run those high pressures (I am guessing this has to do with the strength of the steel primarily). If you go over by a little, you are probably OK and you ensure there will be no valve float at lower RPMs. I think the 901 springs would be fine with a stock cam.
One last thing, I think Gtex (Greg) had problems with valve float when he used the springs recommended by Crane for his cam. He then installed some Comp Cams springs with higher spring pressures and everything has worked out OK. So that would be at least one example that going over (a little) on the spring pressures can be OK.
My take on spring pressures is that if you are under the recommended pressure, you will have valve float at lower RPMs than the manufacturers predicted point for float. If you go over by a lot, you will wipe your cam lobes since the cam was not engineered to run those high pressures (I am guessing this has to do with the strength of the steel primarily). If you go over by a little, you are probably OK and you ensure there will be no valve float at lower RPMs. I think the 901 springs would be fine with a stock cam.
One last thing, I think Gtex (Greg) had problems with valve float when he used the springs recommended by Crane for his cam. He then installed some Comp Cams springs with higher spring pressures and everything has worked out OK. So that would be at least one example that going over (a little) on the spring pressures can be OK.
Post Fiend
Joined: Jan 2003
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From: Iowa
Also greg is running a hydraulic roller cam. You can get away with it with a roller cam. Roller cams are more agressive than regular cams; you need more spring pressure to keep the lifter on the lobe.
I think you could get away with the recommended springs for the 901 on a stock cam. Ford made springs with the same or slightly more pressure on some of their engines, so I think you'll be ok. Just dont put on any triple valve springs or anything like that.
I think you could get away with the recommended springs for the 901 on a stock cam. Ford made springs with the same or slightly more pressure on some of their engines, so I think you'll be ok. Just dont put on any triple valve springs or anything like that.
