Valve Springs

John Scott · 01-16-2015, 06:00 PM

I have a street/strip Nova with 355 SBC...GM casting cylinder heads. Cam is 0.480/0.480 and about 280-282 advertised duration. I don't know anything else about the cam. I'm wondering what kind of spring pressures (seat and open) do I need when selecting new valve springs. It is at about 6000 rpm crossing the line.

Thanks,
John

pmrphil · 01-16-2015, 09:58 PM

If the studs are not yet converted to screw-in (pressed) you will want to stay with something not more than maybe 100 seat and 250 open - the pressed-in studs have a tendency to pull out even with the Z-28 springs.

John Scott · 01-17-2015, 09:55 AM

Thanks pmrphil

Yes, I will be using screw in studs. I was looking at these springs:

http://www.jegs.com/i/COMP+Cams/249/26981-16/10002/-1

COMP Cams 26981-16 - Comp Cams Beehive Valve Springs Details

Small Block Chevy
Designed for hydraulic or solid flat tappet cams cams as well as hydraulic rollers
.525" maximum lift, 1.240" O.D.
Will work with most Small Block Chevy heads with no machining required.

SpecsOD: Top 1.065" Bottom 1.240"
ID: Top .650" Bottom .825"
Seat Pressure: 110 lbs @ 1.700''
Open Pressure: 292 lbs @ 1.1175''
Coil Bind: 1.115"
Spring Rate: 347 lbs/in

The Comp website has them listed for use with a cam which I believe is similar to the one in my car.

Thoughts or opinions?

Thanks,
John

Eman · 01-17-2015, 12:09 PM

Look at Competition products website. They have a great assortment of springs available at a good price. I use Howards stuff in my motor.
Is this a hydraulic or solid? What springs are on it now?
The other BIG thing with flat tappets is the oil you use. I have used Valvoline VR-1 10w-30 and now use Lucas Hot Rod oil 10w-30.

John Scott · 01-17-2015, 12:16 PM

Quote:

Originally Posted by Eman

Look at Competition products website. They have a great assortment of springs available at a good price. I use Howards stuff in my motor.
Is this a hydraulic or solid? What springs are on it now?
The other BIG thing with flat tappets is the oil you use. I have used Valvoline VR-1 10w-30 and now use Lucas Hot Rod oil 10w-30.

Eman, It's a hydraulic flat tappet cam. Not sure on specs of springs, they were in there when I bought the car. They are single with damper. I'll check out Competition products. Thanks.

Eman · 01-17-2015, 10:36 PM

Much depends on the cam and your intentions. I've had good luck on hydraulics with the basic Z-28 style spring. Most will be fine up to 6k RPM. If possible remove and ck your springs. Installed height is very important. You can boost the pressure a little by shortening installed height just make sure you have enough clearance for coil bind. Be careful about too much pressure or you'll wipe out a lobe.

01-16-2015, 06:00 PM	#1
John Scott Junior Member Join Date: Apr 2009 Location: New Brunswick, Canada Posts: 69 Likes: 1 Liked 0 Times in 0 Posts	Valve Springs I have a street/strip Nova with 355 SBC...GM casting cylinder heads. Cam is 0.480/0.480 and about 280-282 advertised duration. I don't know anything else about the cam. I'm wondering what kind of spring pressures (seat and open) do I need when selecting new valve springs. It is at about 6000 rpm crossing the line. Thanks, John Last edited by John Scott; 01-17-2015 at 10:47 AM.

01-16-2015, 09:58 PM	#2
pmrphil Member Join Date: Aug 2010 Location: CT Posts: 386 Likes: 1,256 Liked 248 Times in 107 Posts	Re: Valve Springs If the studs are not yet converted to screw-in (pressed) you will want to stay with something not more than maybe 100 seat and 250 open - the pressed-in studs have a tendency to pull out even with the Z-28 springs. __________________ Phil Molski S/C 1623

01-17-2015, 09:55 AM	#3
John Scott Junior Member Join Date: Apr 2009 Location: New Brunswick, Canada Posts: 69 Likes: 1 Liked 0 Times in 0 Posts	Re: Valve Springs Thanks pmrphil Yes, I will be using screw in studs. I was looking at these springs: http://www.jegs.com/i/COMP+Cams/249/26981-16/10002/-1 COMP Cams 26981-16 - Comp Cams Beehive Valve Springs Details Small Block Chevy Designed for hydraulic or solid flat tappet cams cams as well as hydraulic rollers .525" maximum lift, 1.240" O.D. Will work with most Small Block Chevy heads with no machining required. SpecsOD: Top 1.065" Bottom 1.240" ID: Top .650" Bottom .825" Seat Pressure: 110 lbs @ 1.700'' Open Pressure: 292 lbs @ 1.1175'' Coil Bind: 1.115" Spring Rate: 347 lbs/in The Comp website has them listed for use with a cam which I believe is similar to the one in my car. Thoughts or opinions? Thanks, John Last edited by John Scott; 01-17-2015 at 10:36 AM.

01-17-2015, 12:09 PM	#4
Eman Member Join Date: May 2014 Location: E TN Posts: 442 Likes: 14 Liked 105 Times in 60 Posts	Re: Valve Springs Look at Competition products website. They have a great assortment of springs available at a good price. I use Howards stuff in my motor. Is this a hydraulic or solid? What springs are on it now? The other BIG thing with flat tappets is the oil you use. I have used Valvoline VR-1 10w-30 and now use Lucas Hot Rod oil 10w-30.

01-17-2015, 10:36 PM	#6
Eman Member Join Date: May 2014 Location: E TN Posts: 442 Likes: 14 Liked 105 Times in 60 Posts	Re: Valve Springs Much depends on the cam and your intentions. I've had good luck on hydraulics with the basic Z-28 style spring. Most will be fine up to 6k RPM. If possible remove and ck your springs. Installed height is very important. You can boost the pressure a little by shortening installed height just make sure you have enough clearance for coil bind. Be careful about too much pressure or you'll wipe out a lobe.