Valve spring stupid question??

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340Duster247

340Duster247

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When choosing a new cam how do you know if you need different valve springs. (hydraulic flat tappit cam)
The motor in my 340 duster was rebuilt years ago and all I know is crane cam, crane valve train, 2.02 j heads with hardened valve seats.
I'm rebuilding the bottom end soon with obviously a new cam, but do I need to valve springs ect...
Sorry if this is a stupid question:violent1:

Thanks guys
 
I just went through the same deal when i switched out the cam in my 408 .Even though they were the same lift ,the spring requirments were completely different.I called the cam manufacturer to get the specs.Installed height ,open and closed pressures were way diiferent between the two ...
 
I would have the springs tested and compare them to the ones recommended by the cam's manufacturer. If they match up okay, run them. If not, replace them.
 
The info on the timing/degree and spec card that comes with a new cam usually includes the recommended spring type (single, dual or triple) and spring rate. You won't know what springs you need until you decide on a cam. If you have a good machine shop around you, I'm sure they could help you out.
 
BrianT said:
I would have the springs tested and compare them to the ones recommended by the cam's manufacturer. If they match up okay, run them. If not, replace them.
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^Good advice on having your old ones checked.
 
Thanks guys. A machine shop/engine builder will be building my motor so I guess they will be able to test the springs and let me know. :)
 
A new motor , a new cam and used valve springs ?
I guess it has been done plenty.
I wouldn't bother though.
If the old springs still check , sell them with the old cam.
 
tubtar said:
A new motor , a new cam and used valve springs ?
I guess it has been done plenty.
I wouldn't bother though.
If the old springs still check , sell them with the old cam.
Click to expand...

bad440 said:
x2 wtf? not a good place to save $ my 2 cents
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I gotta agree here. Tried it several times in my very early days, even with confirmation from a shop on a few sets.......Big mistake in my opinion. Float came in under a thousand street miles later on a few and had one engine break one, replaced it, two weeks later, another.........you get my drift. I learned early that springs are one of the most overlooked "maintenance" items on a modified engine. After that i used to change them even when i didn't have too.....lol. Nothing worse then a 6500 rpm combo all the sudden spittin, sputterin and rolling over on you at 5000 :D.
 
Good choice, didn't skimp there. If the shop is any good, they will tell you what to spend more on and what you can reuse. Talk to them as much as possible so they, and you, know what you want to get out of the engine. Just my 2c
 
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