Stock Magnum valve spring specs?

[MopaR&D]

Anyone happen to know the open/compressed load specs for stock replacement Magnum SB valve springs? I'm about to get a pair of stock rebuilt Magnum heads for a 360 build and I want to see if the stock Magnum springs (and 1.6:1 rockers) will work with my Voodoo 256/262 cam.

 

[UOP]

Not exactly answering your question, but I called Direct Connection when I was assembling my motor and he said the stock magnum springs were too weak for my .506/.506 cam.

 

[dgc333]

They coil bind around .47" I had one of my valve springs break so I put one of the stock springs in the vice to check how much lift they could support until I got a new spring. Not good when you have a .509/.512 lift cam.

 

[64physhy]

The Car Craft article a couple years ago on putting magnum heads on an LA 318 said they put a cam with over .500 on it with stock springs (I think it was .517, I looked it up and posted it where you originally asked yesterday). There is also a section in the tech archives on Moparts that has a lot of info on it.

 

[dgc333]

I find that hard to believe. With the stock .4 ish lift cam the valves start to float a little over 5000 rpm can't imagine trying to use springs that wouldn't have a chance at controlling a.517 lift cam.

Plus, my measurement may have been crude but there is no way I was off by 0.047".

 

[dustoff440]

I am also very interested in this topic. I have new mag springs and my camshaft is just under .500 lift. I researched this and I was told that new stock mag springs would handle up to .500. I had a buddy who spun a stock mag 360 to 5300 without valve float. I dont know if they would handle more but he had a very good aftermarket tach so I know it was accurate, I havent broken my engine in yet to spin it tight enough to see where valve float starts. If there is a problem couldn't it be solved by putting about a .030 shim under the springs??

 

[MopaR&D]

I have a set of Comp 901 springs on my 302 heads I can use instead, I'm guessing they would be better? I just figured the beehive Magnum springs might have advantages over my single w/ damper Comps, but that doesn't look to be the case.