Stock valve springs

[dwg86]

I put a dail indicator on a stock valve spring on cracked 0331 head that I have. I was able to get a little over .550 before the spring bottomed out. The head is nasty dirty, covered in oil mixed with antifreeze. So I don't know how much more I could have got with the valve springs cleaned. I also don't know how close to the retainer got to the valve guide. If you subtract a .060 safety margin, the stock springs should be good for about a .490 lift. That's enough for most high torque cams that folks are using.I am not reccomending that someone use stock springs on a performance cam, just some info for those building a stroker on a budget or concerned about wiping out a cam with higher spring pressure from some of the aftermarket performance springs.

I didn't have a stock rocker arm to see how much lift it could take before it started to bind. That is something I would want to check before I used the stock rockers on a high lift cam.

[SilverXJ]

Did you measure the load at their minimum height?

[dwg86]

No I didn't. I don't have anything to measure spring pressure with.

[dwg86]

I can calculate the open pressure from the stock valve spring specs from alldata.com. The stock closed spec is; 71-79# on the seat at 1.640. Open 202-218 @ 1.216. That would be .420 valve lift. doing the calculations I come up with 330.95# spring rate. At .500 lift the spring pressure would be 244lbs.(I used the high end of the specs 79lbs on seat, and 218lbs open at .420 lift)

The stock spring rate seams high, but the installed pressure is low which keeps the open pressure low.

[SilverXJ]

I forgot about calculating it. I even had a spread sheet laid out so all I had to do was plug the numbers in, which I had.

[Heck]

According to the Chrysler computer the parts counter man looked in, the stock springs are only good for a .430 lift cam. With my crane 753905 with .456/.484 lift, my valve springs didn't bind, but they fatigued till I had less than 40# seated.

[seanyb505]

Yeah Im not getting any float or anything with my stock springs and .465 lift, but Ill probly change them if they get worn out like that.