Valve Spring Questions
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
Valve Spring Questions
I just got my valve springs tested and they are pretty well shot. I'm running a 383 Turbo LT1 at 15psi so I need quite a bit of valve spring to keep it running right. Cam lift is about .540
Calling up Comp cams they suggested two springs for me
1.) 26918
130 @ 1.800
318 @ 1.200 305.28@1.26 Bind at 1.100
2.) 26120
155 @ 1.880 192 @ 1.78
377 @ 1.280 391 @ 1.26 Bind at 1.230
I would tend to lean toward choice #2 but is that going to be too much pressure for my valve train?
What if I just shimmed #1 0.1"? That would give me 161 seat and 330 open.
I'm really confused right now. Not to mention that the outer diameter of #2 is 1.445 not the 1.290 that I know fits on the LT1 head. I really don't want to pull the heads to have the seats machined.
Any suggestions from the peanut gallery?
Calling up Comp cams they suggested two springs for me
1.) 26918
130 @ 1.800
318 @ 1.200 305.28@1.26 Bind at 1.100
2.) 26120
155 @ 1.880 192 @ 1.78
377 @ 1.280 391 @ 1.26 Bind at 1.230
I would tend to lean toward choice #2 but is that going to be too much pressure for my valve train?
What if I just shimmed #1 0.1"? That would give me 161 seat and 330 open.
I'm really confused right now. Not to mention that the outer diameter of #2 is 1.445 not the 1.290 that I know fits on the LT1 head. I really don't want to pull the heads to have the seats machined.
Any suggestions from the peanut gallery?
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
FYI, TPIS lists some specs on their #700-132 spring:
1.270" dia, stock
1.250" min running height, 357lbs
125lbs seat pressure at 1.800"
105lbs seat pressure at 1.850"
Note: Do not exceed 120lbs seat pressure with hydraulic roller lifters.
If you install them at say 1.800", with your .540" lift they would run at 1.260" over the nose. That would be .010" shy of the min running height and give around 350lbs.
If you need to run heavier on the seat, maybe you will need to switch to a solid lifter???
1.270" dia, stock
1.250" min running height, 357lbs
125lbs seat pressure at 1.800"
105lbs seat pressure at 1.850"
Note: Do not exceed 120lbs seat pressure with hydraulic roller lifters.
If you install them at say 1.800", with your .540" lift they would run at 1.260" over the nose. That would be .010" shy of the min running height and give around 350lbs.
If you need to run heavier on the seat, maybe you will need to switch to a solid lifter???
Last edited by 65Z01; Mar 22, 2007 at 12:59 PM.
Safety Car
Joined: Sep 2002
Posts: 4,030
Likes: 6
From: Maryland
I just got my valve springs tested and they are pretty well shot. I'm running a 383 Turbo LT1 at 15psi so I need quite a bit of valve spring to keep it running right. Cam lift is about .540
Calling up Comp cams they suggested two springs for me
1.) 26918
130 @ 1.800
318 @ 1.200 305.28@1.26 Bind at 1.100
2.) 26120
155 @ 1.880 192 @ 1.78
377 @ 1.280 391 @ 1.26 Bind at 1.230
I would tend to lean toward choice #2 but is that going to be too much pressure for my valve train?
What if I just shimmed #1 0.1"? That would give me 161 seat and 330 open.
I'm really confused right now. Not to mention that the outer diameter of #2 is 1.445 not the 1.290 that I know fits on the LT1 head. I really don't want to pull the heads to have the seats machined.
Any suggestions from the peanut gallery?
Calling up Comp cams they suggested two springs for me
1.) 26918
130 @ 1.800
318 @ 1.200 305.28@1.26 Bind at 1.100
2.) 26120
155 @ 1.880 192 @ 1.78
377 @ 1.280 391 @ 1.26 Bind at 1.230
I would tend to lean toward choice #2 but is that going to be too much pressure for my valve train?
What if I just shimmed #1 0.1"? That would give me 161 seat and 330 open.
I'm really confused right now. Not to mention that the outer diameter of #2 is 1.445 not the 1.290 that I know fits on the LT1 head. I really don't want to pull the heads to have the seats machined.
Any suggestions from the peanut gallery?
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
I'm not sure how long I've had these valve springs. Probably a few years, under 5 for sure. They are behive springs, but are worn out. 115# seat and 250# open.
Why can't you use more than 120# seat for hydraulic rollers? I thought people ran them at the 150# level without problems.
Why can't you use more than 120# seat for hydraulic rollers? I thought people ran them at the 150# level without problems.
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
I just got off the phone with Crane Cams and they told me that they didn't have anything in the stock spring diameter. They also said with a 2.02" intake valve that there is an extra 62# of pressure on the back side of the intake valve with 15psi going into the engine.
So it looks like I really do need something in the +150# range.
So it looks like I really do need something in the +150# range.
Safety Car
Joined: Sep 2002
Posts: 4,030
Likes: 6
From: Maryland
Ok--but how many miles, approximately? I am just curious as to how long springs last in a preformance application. A few years is not long.
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Melting Slicks
Joined: Apr 2001
Posts: 2,877
Likes: 7
Agreed - I ran these on my LS6 with a big .600 lift cam with no problems at all. The guy I sold it too is still running strong will over 10k miles. they are expensive but a nice valve spring
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
Well, I called Comp Cams and they said I could use the 26918 with some 0.060 shims. That would put my seat at 155# and open at just over 300# given a 0.536 lift.
Not ideal, but much better than what I had. And since I'm not going to pull the heads to machine the seats it may be my only option.
Not ideal, but much better than what I had. And since I'm not going to pull the heads to machine the seats it may be my only option.