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New Springs on Stealth Heads and Lifter Preload?

eagleone1983

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Engine is a 383, I have the Comp Cams XE275HL which has .525" of lift. Engine has been in the car running great since 2012. I could've sworn when I bought the heads that I looked over everything that needed to be done in order to run with my combo. I changed out the locks and keepers to 10 degrees, maybe 440source changed their spring recommendation but here I am wondering if I should now change my springs.

Never thought about them before but I dug into my motor in the last week because of a noisy valve train and had a lot of rocker arm movement side to side so I corrected that issue and as I started inspecting things that's where I noticed the springs were still the stock Stealth ones.

I'm not an engine builder nor am I any expert. Since it's been running this long without issue should I just not worry about it? I've never noticed valve float before when driving though I also would have no idea what it sounds like but I'm sure it would be noticeable.

Second question, after watching numerous videos on setting lifter preload I've noticed most of them have noticeable up and down movement in the pushrod before they tighten up the rocker arm adjustment. My pushrods do not have any up and down movement at base lobe with the rocker adjustments fully in (most loose setting). I'm thinking my engine builder used a pushrod that gave me 0 preload when everything was bolted down but now that makes things difficult to really know if that is the case without taking off the intake manifold. Is there anyway to verify any of this without taking off the manifold?
 
The springs are likely OK, but the only way to tell is to check all the spring pressures. If going this far to check spring pressures, the cost of new springs is not much considering the labor involved.
If you have adjustable rockers and have lifter preload with the adjuster all the way up, then the pushrods are too long.
 
The springs are likely OK, but the only way to tell is to check all the spring pressures.
If you have adjustable rockers and have lifter preload with the adjuster all the way up, then the pushrods are too long.

That's what I was afraid of. This will be the third time I've had to buy pushrods. The first engine builder put 8.5" on it. Then I took it to another place and they put 8.45" on it. I guess it's time I just learn to measure for length myself.
 
You can run the XE275HL with stock style rockers and pushrods if you choose. I have run them both ways
 
That's what I was afraid of. This will be the third time I've had to buy pushrods. The first engine builder put 8.5" on it. Then I took it to another place and they put 8.45" on it. I guess it's time I just learn to measure for length myself.

What rocker arms are you using?
Also, thank you for your service.
 
Comp Cams sells a couple different type of hydraulic lifters. One type is built to rev a little higher (500-1000 rpm) and requires adjustable rockers. This type of lifter is not to have any pre-load, just zero lash. The regular Comp Cams hydraulic lifters can be installed with factory rockers. You should check to see which type of lifter your motor has. Only reason I posted was I saw you have adjustable rockers thought you might have the hi rev Comp Cams lifters.
 
The lifters I have are the ones Comp recommended for the cam, p/n 822-16. I don't see anything on the website about preload and don't have the original install instructions but I'm fairly certain they called for preload
 
Comp's changed their recommended preload over the years but the last set of standard 822-16s I used called for .020-.050 preload and some guys have run to .100 and beyond with the only noticeable effect being less noise. There's enough travel in the plunger that as long as you're not too near the top or bottom, it's not super critical like valve lash on a solid is. I used to set mine to be right about .040 and to have no more than one full adjuster thread exposed underneath the rocker arm.
 
The on-line instructions for the rocker arms don't state the adjuster range of the rocker adjuster.
An adjustable pushrod is the right way to check preload, but you need to know the correct number of turns for the rocker adjuster first.
I think many say 2-turns down, or 2 threads showing under the rocker arm, is where many adjusters should be set when you have the correct pre-load on the lifter.
With the 2 turn / thread setting, I try to get 0.040" lifter preload.

With your setup, sounds like standard offset rocker arms, but if using the higher offset intake rocker arms (like 0.700" + offset), the intake pushrod really needs to be slightly longer than the exhaust.
 
IFRC the seat height is further down in the lifter on the Comp anti pump-up lifters, can’t remember exactly, but something in the neighborhood of .030”. This could effect your required pushrod length.

I don’t see any problem running the stock Stealth springs with that cam...the stock Stealth springs are 130#s at the seat, 330#s at ~.510” lift. As long as you don’t coil bind, I think you’ll run out of cam before you float the valves with that cam. In fact, you proved it, thanks for the data point.

Sidebar: I see you’re likely stationed at HAFB. I was stationed there 3 times, loved everyone of them.
 
My pushrods do not have any up and down movement at base lobe with the rocker adjustments fully in (most loose setting).

So you are saying that if you back the adjuster all the way out, the pushrod is pinned against the rocker arm?
 
,....I think you’ll run out of cam before you float the valves with that cam.

With that cam in a 383, I think he'll have the lifter go south well before that cam reacheds the end of it's usable operating range.
 
You mean pump up and hold the valve off the seat, or exit the lifter bore?

Not exit the lifter bore.

Could pump up, but usually the lifter plunger in todays lifters are overwhelmed buy fast lobe rates and spring pressures and begins collapsing as rpm goes up. This will be more noticable in the smaller cu.in. higher rpm motor like the 383.
 
The “correct” position for the adjuster screw on that rocker is one turn down from all the way seated(as high as it will go)...... within +/- one turn.
If you are down more than one turn, the pushrod doesn’t get oiled.

The “number of threads showing” method does not apply here.

So, with the adjuster set to one turn from seated, you’d like the lifter preload to be where you want it.
The thread pitch on the adjuster is 20/in, so .050” per turn.
If you backed the adjust off all the way, and you just barely had free play at the pushrods...... then they are the right length.
Run the adjuster down roughly one turn, and you’ll have about .050” preload.

If you don’t have any free play with the adjuster backed all the way off, you might still be okay, but you’d want to get a checking tool to see just how much longer than “ideal” your pushrods are.
 
So it sounds like I can adjust the lifter preload by turns as opposed to having to go through each one while it sits on the cam base since I'm going by turns and not so much feel? They were all equal before I pulled the rockers so im not worried about any one of the lifters being off.

I did #1 and #3 rockers rotating on base before I adjusted and only did one full turn as that is what felt right and measured out to what would be close assuming I'm at 0 preload when the shaft is bolted down.

I've guess I've got no reason to question the pushrod size since the shop that did it is Mopar oriented and he races quite a bit and wins so I'm sure he knows what hes doing.
 
So you are saying that if you back the adjuster all the way out, the pushrod is pinned against the rocker arm?

Yes, no up down movement but I can freely spin it between my fingers with very little resistance felt.
 
What PRHeads said. As I mentioned, I don't know much about those rocker arms. Sounds like they have a cup end on the adjuster so the pushrods are ball/ball? and not ball/cup pushrods?
 
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