Valve spring installed height

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MomsDuster

MomsDuster

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Ok folks, I just picked up a set of Stealth heads from 440 source. My first go around with aluminum heads. I’m preparing to install my springs and they call for 1.90” +/- .020 installed height. After measuring one head I’m getting variances from 1.860”-1.878” Now by my calculations they all are tight and should be cut. So I’m thinking I’ll get the cutter/arbor and a pack of shims and do it myself. I’m not one to back down to a challenge and learn some new skills. Looking for some helpful input/advice as I move forward. Thanks
 
Spring range is 1.88-1.920.
So at worst, some are .020 shorter(1.860) than the “desired” height.
Depending on the spring rate, that difference in height may only amount to a few lbs of variation(if the spring is 400lbs/in, that .020 is 8lbs of force).

It’s not at all uncommon for a box of springs to have a 10lb or more variation between the 16 pieces.
Have them tested and then Mix n match……lower springs on shorter heights/stiffer springs on taller heights.

Then again……..is 1.88-1.92 really going to give you the “correct” spring force for what you’re doing?
 
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If you use + or - 050 keepers, which is one way you can go, check the measurement. I have found they often provide less than 050.
 
I would never cut spring pockets deeper to increase spring height. Never, ever, ever. EVER. NEVER. There are offset valve keepers and retainers to achieve that. There is usually water jackets REAL CLOSE under the spring pockets. Now, read my first sentence again. lol It's just not a good idea.
 
RustyRatRod said:
I would never cut spring pockets deeper to increase spring height. Never, ever, ever. EVER. NEVER. There are offset valve keepers and retainers to achieve that. There is usually water jackets REAL CLOSE under the spring pockets. Now, read my first sentence again. lol It's just not a good idea.
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I’m picking up something here Rob, are you saying Never?
:lol:
Message received!
 
MomsDuster said:
I’m picking up something here Rob, are you saying Never?
:lol:
Message received!
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I'll tell you what is acceptable though. Enlarging the spring pockets for a bigger diameter spring. I did that to one of my slant 6 heads, but again, I did not cut DOWN into the head at all.
 
RustyRatRod said:
I would never cut spring pockets deeper to increase spring height. Never, ever, ever. EVER. NEVER. There are offset valve keepers and retainers to achieve that. There is usually water jackets REAL CLOSE under the spring pockets. Now, read my first sentence again. lol It's just not a good idea.
Click to expand...
I agree for the most part. There are some applications where it makes sense to cut the seat. An example is the EQ magnum head. EDIT: ( I don’t know if this applies to the China EQ's) It has a very short installed spring height. Sometimes offset keepers/ retainers won't get you where you want to be. Luckily they have some room to cut.
Some heads are not safe to increase the diameter even at stock depth without hitting water. If increasing the diameter on some small block chevy heads you have to place a shim on the seat and cut the pocket to the top of the shim to stay out of the water. The seat gets thinner as you increase the diameter.
Ran into this yesterday on the dyno. The motor started blowing water vapor out the breathers on breakin. Had to shut it down. This is what I found in the picture.

IMG_20231118_125824.jpg
 
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65TerrorCuda said:
Is that repairable or total junk now?
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I don't know. Even if it could be welded, the cast iron cylinder head welding wizard around here has retired. And even if he was still welding and could weld it, it might not be cost effective. The builder and customer will have to work that out.
 
Yeah, cast iron is some really picky stuff when welding. That's gonna be a tough one.
 
Not the first time I’ve seen that exact situation.
You really gotta leave the shim in the pocket when cutting factory sbc heads for larger diameter springs.
 
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