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Valve Spring Pressures

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The spring pressures from Kibble white and R/D are off in terms of installed height pressure and at lift pressure between them. The R/D springs compare to Ferrea in terms of spring pressure.

What spring pressure(s) are valid for radical cams with high lift short duration?

The Kibble White valves have lost a TON of installed height seat pressure. The full lift pressure is larger than the RD or ferrea.

What is the minimum safe operating installed pressure and full lift pressure @ 11,200RPM?

KIBBLE WHITE

Installed Height

Exhaust 1.360-1.370 72#, .375 184#

INTAKE 1.275-1.285 40#, .375 130#

BASE Thickness

Intake

Exhaust

LEFT EXHAUST RIGHT

LBS LIFT LBS

56 1.36 56

166.5 -0.375 161

175 -0.4 173

LEFT INTAKE RIGHT

LBS LIFT LBS

25 1.36 27

111 -0.375 116.5

116.5 -0.4 122

SPRING ERROR %

LEFT RIGHT

28.57142857 EXHAUST 28.57142857

10.51051051 14.28571429

LEFT RIGHT

60 INTAKE 48.14814815

17.11711712 11.58798283

R/D SPRINGS 1085 Springs

Installed Height

Exhaust 1.250 - 1.270 60#@1.250, 125#@-.400

INTAKE 1.310 - 1.330 53#@1.310, 117#@-.400

BASE Thickness

Intake 0.11

Exhaust 0.247

EXHAUST

LEFT DIFFERENCE %

55 60 9.0909091

107 125 16.8224299

RIGHT DIFFERENCE %

55 60 9.0909091

110 125 13.6363636

INTAKE .800 coil bind

LEFT DIFFERENCE %

52 53 1.9230769

110 117 6.3636364

RIGHT DIFFERENCE %

45 53 17.7777778

110 117 6.3636364

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What is the minimum safe operating installed pressure and full lift pressure @ 11,200RPM?

Even if you knew the answer to that question, how could you (the common man, without LVDT's Strain Gauges Etc..) dynamically check it?

They give you static dimensions. :busted: :busted:

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Even if you knew the answer to that question, how could you (the common man, without LVDT's Strain Gauges Etc..) dynamically check it?

They give you static dimensions. :busted: :busted:

The KW's are nearly 50% stiffer at .375. After being used 10 hours the KW's checked out to be:

Exhaust

56# installed

166# -.375

Intake

25# installed

116#@ -.375

R/D

Exhaust 1.250 - 1.270 60#@1.250, 125#@-.400

INTAKE 1.310 - 1.330 53#@1.310, 117#@-.400

As checked:

Exhaust

55# installed

110# -.400

Intake

52# installed

110#@ -.400

This is just a static test to see what the spring rates are compared to new. In comparing these numbers the pressures are significantly different between manufacturers.

This brings the question: "what is the minimum pressure needed to keep the valve train from floating a valve?"

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What is the minimum safe operating installed pressure and full lift pressure @ 11,200RPM?

To answer the question, the same as it is when the engine is at rest...it doesn't change.

I think your question is really "why do the KW have such high seat pressures and over the nose pressures?"

The answer to that is, the stock springs are just barely adequate brand new on a Ti valve. The stainless KW valve is quite a bit heavier and needs more spring to follow the cam at the same RPM. Since its a straight rate spring, the pressure will continue to rise as it is forced over the nose of the cam. Regarding your probable primary concern, you wont wear out the cam or followers with the heavier springs.

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To answer the question, the same as it is when the engine is at rest...it doesn't change.

I think your question is really "why do the KW have such high seat pressures and over the nose pressures?"

The answer to that is, the stock springs are just barely adequate brand new on a Ti valve. The stainless KW valve is quite a bit heavier and needs more spring to follow the cam at the same RPM. Since its a straight rate spring, the pressure will continue to rise as it is forced over the nose of the cam. Regarding your probable primary concern, you wont wear out the cam or followers with the heavier springs.

If the KW have decreased in psi/inch there is a point where the springs cannot do their job. At what loss in pressure is there concern? When comparing 3 sets of springs only 2 have the same spring rate when new.

In trying to compare the Ferrea and R/D the spring pressure is less than the KW's new.

I don't have a set of Ferrea valves to weigh so I am excluding the weight difference from KW to Ferrea. However, the R/D springs are HD springs for stainless. Since they are about the same spring rate as Ferrea, I imagine the 450 head needs no more than the psi they give.

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The KW springs may have a work loss built into the spring rate when new. How much pressure isnt really the issue with these heads as much as the resonance that sets in on some springs. Notice, none of them have dampers...If the things start bouncing you end up with valve float when you're not even revved up very high.

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