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Old 11-06-2013, 12:39 PM
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small block 400 valve springs

Getting to the point I'm about done with building my small block 400 just got the pushrods and roller rockers in and was just wondering do I need different valve springs to use the full roller rockers if so what springs do I need the cam is a solid roller valve adj int/.020 exh/.020gross valve lift int/.525 exh/.525 duration int/268 exh/268 lope lift. 3510 int and exh lope separation 110

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Old 11-06-2013, 01:17 PM
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Originally Posted by 87 gmc View Post
Getting to the point I'm about done with building my small block 400 just got the pushrods and roller rockers in and was just wondering do I need different valve springs to use the full roller rockers if so what springs do I need the cam is a solid roller valve adj int/.020 exh/.020gross valve lift int/.525 exh/.525 duration int/268 exh/268 lope lift. 3510 int and exh lope separation 110
Of course you contacted the cam manufacturer for proper spring recommendation right?
Of course you checked for proper pushrod length right?

No your roller rocker won't change your valve spring recommendation.
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Old 11-06-2013, 03:20 PM
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A solid roller camshaft with .525" valve lift, will need at least 130 lb. seat pressure and 350 lb. open pressure or your engine will lose power and may have engine damage above 5,500 RPM due to premature valve float. Agressive roller camshaft profiles with more than .500" valve lift will float the valves earlier in the RPM range than a comparable flat tappet camshaft.

Conventional valve springs that the cam grinder would recommend for a camshaft with .525" valve lift must set up at 1.800" in order to avoid coil bind and that means 0.100" longer valves and the cylinder heads will need machine work to fit larger diameter valve springs.

A good alternative to conventional valve springs are beehive-ovate valve springs. Comp Cams 26918-16 are 1.310" O.D. and will fit your heads without machine work. They have 162 lb. seat pressure at 1.700" and 357 lb. open pressure at 1.175" (.525" valve lift) and they coil bind at 1.100". They require Comp Cams 795-16 retainers and Comp Cams 613-16 locks. Those are single valve springs and do not need a damper spring because the ovate wire controls spring oscillation.
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Old 11-06-2013, 03:24 PM
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Do you have the manufacturer and grind number of the cam you're using?
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Old 11-06-2013, 09:19 PM
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what are on the heads now? you do have screw in studs? thats a very low lift for a solid roller,is it an old design?
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Old 11-06-2013, 09:56 PM
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what are on the heads now? you do have screw in studs? thats a very low lift for a solid roller,is it an old design?
Yah its older, its a comp magnum retrofit...
224/224@.050
525/525
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Old 11-06-2013, 09:57 PM
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Do you have the manufacturer and grind number of the cam you're using?
http://www.summitracing.com/int/part...make/chevrolet
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Old 11-07-2013, 06:21 AM
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The recommended springs for that cam is comp# 977-16 which has a seat pressure of 155@1.850, 420@1.25, a rate of 441# and has an O.D. of 1.46

Not sure what you currently have but stock 400 springs won't do it. The recommended springs are dual springs so the stock spring seat isn't big enough in diameter and will need to be cut along with bigger retainers.

Not saying you have to go with those exact Comp Cams springs but you will need something comparable.
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Old 11-07-2013, 07:02 AM
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The valve springs that Comp Cams would recommend for that cam are 977-16. Those valve springs are conventional dual spring design that are 1.460" O.D. and .700" I.D. and they set up at 155 lb. seat pressure at 1.850" installed height. They will have 386 lb. open pressure at 1.325" (.525" valve lift) with coil bind at 1.195". Intake and exhaust valves that are 0.100" longer will be required and taller valve covers may be necessary. In order to fit those valve springs, the spring pockets must be machined from 1.290" to to 1.500" O.D. and deepened at least .050" or use + .050" locks. You will need 10 degree Comp Cams 740-16 retainers and 613-16 locks.

Get Comp Cams beehive/ovate valve springs instead and they will fit without machine work. They will provide the required valve spring pressure for a mechanical roller camshaft with .525" valve lift.

Burn a copy of this and give it to your machinst.
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Old 11-07-2013, 07:28 AM
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Originally Posted by MouseFink View Post
Get Comp Cams beehive/ovate valve springs instead and they will fit without machine work. They will provide the required valve spring pressure for a mechanical roller camshaft with .525" valve lift.

I'll just hang around awhile to see what beehive spring will work with a solid roller and still fit in the stock seat. The only thing worse than no answer is the wrong answer.

Inadequate springs will absolutely destroy solid rollers.
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Old 11-07-2013, 11:15 AM
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Peterson American Co. (PAC) 1518 valve springs
Beehive, ovate, single nitrited valve spring.
These valve springs will have excellent control of a camshaft with .525" valve lift. However, do not expect ecpect long life from the exhaust valve seats on no lead gasoline unless you have stellite valve seat inserts installed.
161 lb. seat pressure @ 1.700" (stock height)
325 lb. open pressure @ 1.175" (.525" valve lift)
336 lb. @ 1.140" (.560" max valve lift)
1.080" coil bind
1.290" O.D. (stock spring seats)

Beehive - ovate valve springs can keep the valve train under contol with less spring pressure. The ovate spring wire permits more valve lift than springs made of round wire set up at the same assembled height. The design of ovate wire does not require a inner spring damper in order to prevent spring oscillation.

I am using Comp Cams 26915 beehive-ovate 1.290" O.D. valve springs with a Comp Cams hydraulic roller camshaft that has .500" valve lift with Comp Cams 975-16 reduced travel hydraulic roller lifters, preloaded at .005" (1/8 turn). The beehive springs were equalized on the heads with 137 lb seat pressure at 1.700" and 294 lb. open pressure at 1.200", and 1.100" coil bind. I did not have to machine the stock SB Chevy spring pockets. My camshaft does not need bone crushing spring pressure, especially if I want to preserve the exhaust valve seats using no lead gasoline.
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Old 11-07-2013, 11:31 AM
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That PAC spring only has a spring rate of 313 lbs/in and Comp recommends 441 lbs/in. Even if you get the correct seat pressure your over the nose pressure needs to be in the 370# range and you'd only have around 320#

That's a hyd roller spring not a solid roller.
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Old 11-07-2013, 12:32 PM
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The cam lobe profile determines how much spring pressure is required. Old school camshafts with more than .530" valve lift must use solid lifters because hydraulic lifters cannot effectively follow the cam lobes with the spring pressure that is required. That is why I used Comp Cams 975-16 reduced travel hydraulic lifters. The reduced travel or short travel lifters follow the cam lobes with the appropriate amount of spring pressure and cannot loft over the nose of a roller cam profile and pump up. That is because the reduced travel lifters have no where to pump up to. Most people build engines according to the limit of their bank account and do not like those lifter because they are expensive and cannot believe they are designed to operate at .005" preload.

In 2000, GM introduced beehive-ovate valve springs in the LS engines using light weight retainers. The LS7 engines use light weight titanium intake valves and soldium filled exhaust valves. The light weight equipment permits the use of weaker and no-lead gas friendly beehive-ovate valve springs. The beehive-ovate valve springs are used in the LS7 engines equipped with a hydraulic roller camshaft that has .590" valve lift.

Last edited by MouseFink; 11-07-2013 at 12:50 PM.
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Old 11-07-2013, 01:06 PM
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Originally Posted by MouseFink View Post
The cam lobe profile determines how much spring pressure is required.
Exactly, which is why when Comp Cams recommends using a spring with a particular rate for one of their cams you really should follow their advice.

What does your application have to do with what the original poster was asking for?
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Old 11-07-2013, 02:03 PM
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Comp Cams recommended 987-16 dual valve springs with my camshaft with .500" valve lift. Those springs are 1.430" O.D. and set up at 121 lb. seat pressure @ 1.800" with 306 lb. open pressure @ 1.300". Those springs require machine work to open the stock 1.290" pockets to 1.440" O.D. Comp Cams does not tell anyone that those valve springs will also require longer valves and taller valve covers.

I chose to use Comp Cams 26915-16 beehive-ovate valve springs with 137 lb. seat pressure @ 1.700" and 294 lb. open pressure. No machine work is required. My set of ARP 3/8" screw-in rocker studs can handle up to 140 lb. seat pressure and 350 lb. open pressure before risk of breaking. The spring Comp Cams recommend for the OP camshaft, needs 7/16" rocker studs and rocker arms that fit 7/16" studs.

The OP camshaft only has .025" more valve lift than my camshaft so my camshaft makes a good comparison. Better valve spring choices are available today without going to the unnecessary expense of having the heads machined.

Last edited by MouseFink; 11-07-2013 at 02:13 PM.
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