Adjusting Lifter/Rocker - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums

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post #1 of 16 (permalink) Old 06-08-2016, 04:32 PM Thread Starter
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Adjusting Lifter/Rocker

Apparently Chippewa Valley Engine & Machine out of Eau Claire, WI did a very poor job building this LT1 that only has 9k and runs like dogshit. First of all, the lifters/valve lash is loose as all hell, judging from the clicking and clacking. Second, the valve stem seals aren't seated properly. 3rd, the spark plug gap was set at .060+. Its no wonder I had to change out an ignition coil. And tape isn't the proper way to plug a vacuum line. I hope they read this.

Anyhow, Comp Cams 304 cam, 1.52 Comp Cams roller rockers, and the matching package deal. I'm trying to figure out how to adjust the lifter preload and rocker arms to the proper position. I've only done valve lash and non-adjustable rockers before. I can't find any info on where/what position the lifters are supposed to sit when tightening the rocker arms to spec. How can I tell that the hydraulic lifters are in that mysterious default position that is no where mentioned? The only thing mentioned in the Comp Cams guide is to not pump the lifters up. Do lifters bleed down after xx amount of days or is it a manual procedure? Do they return to a neutral position from an internal spring in which directs me to where i need to set my tension on the lifter nut?

Last edited by markfothebeast; 06-08-2016 at 04:40 PM.
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post #2 of 16 (permalink) Old 06-08-2016, 07:05 PM
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4th Gen LT1 F-body Tech Articles

1989 jaguar xjs, '93 z/28 eng.& trans. asp pullies,csi,1.7 scorpions,26918 springs, transgo, yank ss3600, homemade shorties,dr. gas x, alvins tune 12.82@104 1.74 60' 3900#
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post #3 of 16 (permalink) Old 06-08-2016, 07:45 PM
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You can also adjust valves using the old red neck method.

You remove valve cover from one side of engine. Crank engine and let idle. loosen nut on 1st rocker arm until clatter is heard. Then tighten nut on rocker until clatter goes away. Tighten nut 1/4 to 1/2 turn more.

Go to next rocker. Do this until all rockers on that side of engine are done. Replace valve cover. Move to other side of engine and repeat process.

Clean up any oil splashed when done.
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post #4 of 16 (permalink) Old 06-08-2016, 08:27 PM Thread Starter
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I read that. The problem is that the alternator needs to be put back in again
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post #5 of 16 (permalink) Old 06-08-2016, 10:10 PM
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You can run it without the alternator. Just make sure you isolate the big red wire, so it does not short to ground.
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post #6 of 16 (permalink) Old 06-09-2016, 05:43 AM
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Having just gone through this myself, go with the 'car running' method. I set preload with the engine off and never could get them to quiet down. That being said, roller rockers will always make a bit of noise - even after they've been adjusted properly
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post #7 of 16 (permalink) Old 06-09-2016, 08:39 AM
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On stock 3/8-24 rocker studs with 1.5:1 rockers, turn the engine so the lifter for the rocker arm you are adjusting is on the base circle of the cam lobe, tighten the rocker nut until you have zero lash, then go 3/4 turn more. Done... Go to the next rocker and adjust it.

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post #8 of 16 (permalink) Old 06-29-2016, 01:03 PM Thread Starter
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I'd like to start over by doing the initial preload adjustment as if it were a new installation. For my own satisfaction and because I want to have a complete understanding of hydraulic lifter preload and fine tuning preload. Please bare with me, I have a lot of questions about lifters and lifter preload. I did read the Shbox website but have to go over it again.

Here's what I'd like to know about hydraulic lifters.
1. To set initial preload, is it required that the lifter is bled down?
2. Does a lifter naturally bleed down after xx amount of time?
3. If the lifter is bled down and the rocker arm/pushrod are loose, does the hydraulic lifter return to a neutral/centered position?
4. Is the ideal initial preload at this neutral position so that the lifter has adequate hydraulic adjustment to keep the tension on the pushrod from being too tight or too loose?
5. What causes the excessive clicking noise in the lifter? Is it extending to its mechanical limit?

Once I finally set the initial preload I understand that I adjust each rocker arm nut with the engine running until each lifter creates less noise. I am looking to get a feel for where the pushrod is sitting in the lifter since I am unable to see each one.



But before I set the preload - is there a method to push a valve stem seal into place without removing the spring? Cyl 1 exhaust valve stem seal was off. Not sure why but it could be that it was not installed properly. My cousin mentioned that the valve guide could be too long.
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post #9 of 16 (permalink) Old 06-29-2016, 02:02 PM
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1. To set initial preload, is it required that the lifter is bled down?
Source of contention since they will bleed down over time. Soak the lifters in oil for a few hours, stick them in, and have at it. Never failed for me...Do not set lash with dry lifters.
2. Does a lifter naturally bleed down after xx amount of time?
Yes
3. If the lifter is bled down and the rocker arm/pushrod are loose, does the hydraulic lifter return to a neutral/centered position?
If you remove spring pressure, the lifter plunger will return to an unloaded state. The point where the pushrod juuuuust touches the lifter is "zero lash".
4. Is the ideal initial preload at this neutral position so that the lifter has adequate hydraulic adjustment to keep the tension on the pushrod from being too tight or too loose?
Yes. You start from the unloaded position, and then create the preload.

Once I finally set the initial preload I understand that I adjust each rocker arm nut with the engine running until each lifter creates less noise.

NO. Set the preload cold, and then start the car and get the engine warm. Pop off the covers, start the car, and loosen each locknut until they start to click. Then slowly tighten them until the clicking stops - then go 1/2-3/4 more. Lock them down.

Last edited by AtlantaDan; 06-29-2016 at 02:09 PM.
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post #10 of 16 (permalink) Old 06-29-2016, 02:06 PM
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you want to set preload from zero lash, which is the lifter fully returned to its extended position (with the lifter touching the retaining clip). so basically, everything is JUST barely touching when the valve is closed.

loosening the entire valvetrain right off and waiting will allow the lifters to return (unless they are completely collapsed or stuck or whatever)

with engine running, this is the point where the clacking just stops.

with engine not running, this is the point you feel a tiny bit of resistance when spinning the pushrod (or with polylocks, you can spin a nice oiled up polylock by hand and feel as soon as it hits zero lash...)

the trick is, once you've placed any load on the lifter, it'll 'bleed down' and kinda act like its at zero lash again, until you release that pressure and wait till it can return.

hope that makes sense

once you're at zero lash, you add preload (3/4 turn or whatever). to recheck preload, you'd need to loosen everything off again. or, alternatively, start the engine, loosen it what you thought the preload was (3/4 turn?), and see if you get clacking just past that point.
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post #11 of 16 (permalink) Old 06-30-2016, 01:08 AM
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I remember the valve lash procedure for cold lashing (aka not running, assembling, on stand, etc) standard small blocks with the 18436572 firing order, never had an issue like this, once you get good at knowing how much preload you should feel on the pushrod you can count on it working everytime.


Bring the engine to top dead center(TDC) for cylinder #1 on compression stroke. Both of the timming marks should be at the 12:00 position or, the timming mark at 0 degrees], and the lifters for #1 should both be at the bottom of thier travel in the lifter bores.

Now the engine is in the #1 firing position.


Adjust the intake valves on cyl #s 1,2,5,and 7
Adjust the exhaust valves on cyl #s 1,3,4,and 8

Then rotate the engine 360 degrees so the timing marks are at 12:00 again, or the timming mark is back at zero degrees.

now the engine is in the #6 firing position.

Adjust the Intake valves on cyl #s 3,4,6, and 8
Adjust the exhaust valves on cyl #s 2,5,6, and 7.

This procedure only works on small blocks with a conventional firing order of 18436572.
it's as simple as that, if you don't know how to adjust valves by the pushrod feel x degree turn method let me know.

Last edited by 99Pewterz286Rag; 06-30-2016 at 01:11 AM.
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post #12 of 16 (permalink) Old 06-30-2016, 11:30 AM
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^^^ I have always done it this way. #1 cyl at TDC both I & E are closed. If one is open you are not at #1 but likely at #6 (if both of those are closed.

for zero lash tighten the poly lock with your fingers until there is no more up/down movement and then go 3/4 turn.

Op, a Haynes or factory Service Manual will help in spelling out how to do this
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post #13 of 16 (permalink) Old 06-30-2016, 06:25 PM
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The factory procedure is pretty safe with the small cams that came from the factory, but as the duration starts to increase with aftermarket camshafts, the number of degrees of base circle diminishes. I have seen guys run into trouble with the factory procedure of doing half of the rockers at #1 firing stroke, and then turning the crank one full turn to the #6 firing position and adjusting the rest. You can easily have a lifter that is not on the base circle (whereas it would have been with a factory camshaft, with factory duration) when you adjust it. No bueno...

I have always used the method of putting each cylinder at overlap, one at a time, and then adjusting the one OPPOSITE it in the firing order. You can write out the firing order on a piece of paper in two rows as a reference if it helps.

Such as:
1 8 4 3
6 5 7 2

When #1 is at overlap, adjust #6. When #8 is at overlap, adjust #5. With #4 at overlap, adjust #7...and so on. I have never had any trouble using this method. With the circle track cams we used, with durations in the mid to high 260 degree range at .050", any other method would be to invite disaster.

And, yes, I recommend 3/4 turn past zero lash (see steveo's post on how to identify zero lash) with 1.5:1 rockers on stock 3/8-24 rocker studs. Other rocker/stud setups will usually require a slightly different number of turns past zero lash. There is a little math involved...

Also, do beware of a 4/7 swap cam with the above procedure. Why you would have a 4/7 swap in an LT1, I don't know, but many race cams in other types of SBC engines are swapped.

One other quick note: in over 28 years of working on SBC's (12 years of which were at a large Chevrolet dealership), I have NEVER had to run an engine with the valve covers off to successfully set up a set of rockers. It makes a colossal mess, and is simply unnecessary, in my opinion.

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Last edited by Dynamic396; 06-30-2016 at 06:42 PM.
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post #14 of 16 (permalink) Old 06-30-2016, 07:02 PM
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yeah I understand what you are saying about larger cams vs stock. I run fairly small cams compared to most and not had any problems doing it following factory procedure with the cam I have now (218/224 with a duration of 268 intake & 276 exhaust).

I completely understand the method you describe and will try that when I swap springs again although after 30k miles, no problems for me so far
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post #15 of 16 (permalink) Old 07-01-2016, 12:46 PM Thread Starter
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I still haven't had time to adjust my preload due to house remodeling. I've rotated the engine a couple times to get a feel for the rocker arm on a particular valve to see where the least amount of tension is applied to the valve spring. I assume this is the position in which the cam has the least amount of lift and is refered to as the "base circle"?

I have a slightly larger than stock cam plus the 1.52 Magnum rockers. Being new to adjusting preload is making me put more thought into how everything is timed.

Would it be much simpler to eyeball the camshaft centerline by watching the rocker arm lift to the highest point and rotate the crankshaft 360 degrees to find the "base circle?

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