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SBC - Hydraulic Roller

I understand that cam manufacturers make spring recommendations that one should follow, but in this case I have the springs in hand before the cam, and I’m trying to throw this thing together on the cheap.

The springs are Howard’s 98445, 120 lbs on the seat, 425 lbs open, 399 rate. I’m going to be looking at a cam in the 220s-230s duration @ .050 and .550ish lift with 1.6 rockers.

Can I run these springs on such a cam?
 

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425 open? At what lift?

Without that, i'm guessing. But that is alot of over the nose pressure. If your cam is a hydraulic FT that will be street driven, then i would not use them - they will wipe the cam in a hurry. I'm running 400 open pressure at .620 lift on a hydro roller that have worked well for a couple of years now with 15 pi of boost pushing against them. But we don't spin it over 6500.

Answer the questions please for better answers.
 

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Looked that spring spec up...that's 425 lbs open, @ .765" lift(1.110" height) 120 lbs seat @ 1.875" height....so at just .550"-ish lift it is going to be a good bit less than 425 lbs open..

.550" lift x 399 lbs/in rate =219.45 lbs gained in .550" of travel....add that to your pressure @ installed height and you will get the new open pressure at your .550" lift.
So, from a 120 lbs @ 1.875" seat height you would end up at 339.45 lbs open @ .550" lift.

120 lbs seat is rather low for a hydro roller cam of that approximate size....you are going to want to set up at around 1.800-1.825" height installed for about 140-150 lbs seat pressure and about 360-370 lbs open @ that .550" lift.

Howards lists that spring in the Competition Products catalog table as both a hydraulic roller and a mechanical flat tappet spring....it is all in the set-up height and valve lift spec and the pressures generated for each on how it is set up.
I have that same spring set-up for mechanical flat tappet use right now

Set it up at the right height and you are good to go on that size range of hydro roller cam.(y)
 

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425 open? At what lift?

Without that, i'm guessing. But that is alot of over the nose pressure. If your cam is a hydraulic FT that will be street driven, then i would not use them - they will wipe the cam in a hurry. I'm running 400 open pressure at .620 lift on a hydro roller that have worked well for a couple of years now with 15 pi of boost pushing against them. But we don't spin it over 6500.

Answer the questions please for better answers.
I’m going roller. Nova nailed it for me below.

Looked that spring spec up...that's 425 lbs open, @ .765" lift(1.110" height) 120 lbs seat @ 1.875" height....so at just .550"-ish lift it is going to be a good bit less than 425 lbs open..

.550" lift x 399 lbs/in rate =219.45 lbs gained in .550" of travel....add that to your pressure @ installed height and you will get the new open pressure at your .550" lift.
So, from a 120 lbs @ 1.875" seat height you would end up at 339.45 lbs open @ .550" lift.

120 lbs seat is rather low for a hydro roller cam of that approximate size....you are going to want to set up at around 1.800-1.825" height installed for about 140-150 lbs seat pressure and about 360-370 lbs open @ that .550" lift.

Howards lists that spring in the Competition Products catalog table as both a hydraulic roller and a mechanical flat tappet spring....it is all in the set-up height and valve lift spec and the pressures generated for each on how it is set up.
I have that same spring set-up for mechanical flat tappet use right now

Set it up at the right height and you are good to go on that size range of hydro roller cam.(y)
Thank you for a thorough answer, especially explaining the math! Glad to hear they can be made to work.
 
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