Heavy springs March 08, 2014 02:12PM
Looking for a set of heavy valve springs for a 3500rpm sbjd 30 series head. Also would like heavy duty keepers. Whom should I get in touch with?
Thanks for the help
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Re: Heavy springs March 08, 2014 11:33PM
Summit-Jegs
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Re: Heavy springs March 09, 2014 09:29AM
What pressure/stiffness should I be looking for?
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Re: Heavy springs March 09, 2014 10:32AM
Usually they use automotive type springs to get enough pressure, and then you will have to machine the spring pocket larger to allow the larger od springs to fit. You will also need spring locators under the spring and you will need automotive type retainers that match the springs and matching keepers. The pressure of the springs will be dependant on whether you have a flat tappet or roller camshaft. You may also need heavier push rods to keep from bending with the higher spring pressure and you should have a steel nose on your cam to keep from breaking the camshaft with the higher spring pressure. As you can see just putting on heavier springs gets expensive pretty quick.
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Re: Heavy springs March 09, 2014 03:49PM
What are the benefits of heavy springs at 3500 RPM? Are they needed? I already have a steel nose, heavy duty push rods, and it's a flat tappet cam.
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Re: Heavy springs March 10, 2014 09:53AM
Heavier than stock springs are required mostly because of the higher than stock boost that you will be running. The intake valve will be trying to close while the boost pressure will be trying to keep it open. The exhaust valve will be trying to close and the exhaust pressure will be trying to keep it open.

Lets say you have a 2" intake valve. The area of the valve would = radius x radius x pie

1 x 1 x 3.1416 = 3.1416 square inches

If you had 50 lbs/square inch of boost you would have

3.1416 x 50 = 157.08 lbs of force trying to keep the valve open.

This is just an example but you can see that you need the heavier springs to overcome the boost or exhaust pressure.
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Re: Heavy springs March 09, 2014 12:12AM
Have a set used very little in a IH 301 NA. Not sure if stiff enough for turbo engine.
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Re: Heavy springs March 10, 2014 01:22AM
Riverside, phil will set you up and at a good cost and the set will work for the next class you build for without buying another set of springs.
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