Valve springs?

[hemiEssex]

My 68 HP 440 has what I believe to be new stock springs, w damper springs in it. It appears to have also had a valve job ( I say appears because I do not know what work was done to it before I bought it but it appears to have been all rebuilt)
My question is:
I am putting a comp cam thumper cam in it.
Specs are:
Gross valve lift I .486 E .473
Lift I 279 E 296
Part number is 279T Thumper series.
I know there is a bazillion opinions on this cam, but I am building a street driver and my wife will be driving it also, so i wanted the sound without the loss of vaccum and drivability. Anyways, I bought the cam and am putting it in.
Do you guys think the stock HP valve springs will work with this cam or do you think I should buy comps springs as well. I know, I know, they are the manufacturer, but some times they just want you to buy their stuff because it is easier than telling you it is okay to use the stock stuff (more money in sales) I really don't want to disturb the valves and heads to do this swap.
Let me have it!! I believe in spending money on parts but sometimes I think ma mopars stuff is just as good as alot of the so called performance parts.
cheers
Steve

 

[khryslerkid]

This is a thought only if you would need new valve springs:

You don't always have to remove your heads to replace your springs. There is a kit that has a tool that will grab your spring from the outside and compress it, allowing you to remove your keepers, thus removing your springs. What keeps the valve from falling down into the head? The kit also includes a set of fittings for different size sparkplugs. You install the correct size fitting into the cylinder that you are working on and place an air hose (constant 100psi prefered) onto the fitting. The air pressure in the cylinder keeps the valves in place while you replace your springs and seals.
It may not work as easily on double spring setups that have a lot of tension but I have used this tool for lesser in changing out valve stem seals, broken springs, ect. (You could always experiment before you tear anything down.)

No recomendations on spring type with the cam you are buying? You are getting close to a 500 lift cam that should require a beefier spring.

They should recomend a high-pump lifter too with this size cam?

 

[Meep-Meep]

The only way to do this properly is to remove a spring (as described above) and measure the pressure at the actual installed height. Compare these numbers to what the cam manufacturer recommends and go from there. My guess is you will need slightly more spring - maybe 110 lbs on the seat vs. the stock Magnum 90 lbs.

 

[RTSrunner]

I agree with checking the pressure @ the installed height.Also check for coil bind with the stock springs,they may be a thicker wire diameter than the Comp springs-or not.If the stock springs are too weak for the cam,you could always use them to break in the new cam and then change to the Comp spring.That is of course if you don't mind pulling the covers and rockers twice.
RT