Rocker Adjustment Issues...

[SchnellGhostTy]

Ok so just putting the engine back together the second time since the rods were hitting the oil pan and I didn't seal the head studs... now when I was going by the book for the rocker arm adjustment/tightening and the first time we got them all done we turned the engine over after and by the time we came back to top dead they were all loose again. So we tighten them again and then the valves start opening. So it seems to either be loose or too tight?!

I'm thinking my lifters are bad?
or are my valve springs too soft?

Thanks guys, let me know what you think...

 

[Quickstop [UK]]

Re: Rocker Adjustment Issues...

What's in your build? Stock parts or a new build?

What method did you use to adjust them?

 

[SchnellGhostTy]

Re: Rocker Adjustment Issues...

Big valves, comp 412 cam. Both came with the truck. the heads I had reconditioned with the valves and springs(dual wound) with all new everything else. I did a full rebuild from there, je pistons, eagle rods ect. Was going out of the syty factory shop manual for pressed rocker rods adjustment/intall ie take up thrash plus 1 full turn

 

[Quickstop [UK]]

Re: Rocker Adjustment Issues...

Have you primed the engine? If the lifters are new in there then they won't be pumped up.

 

[SchnellGhostTy]

Re: Rocker Adjustment Issues...

Primed previously but not since the second time building it back up. I'm guessing I should I prime it again then tighten?

 

[johnboy89]

Re: Rocker Adjustment Issues...

Are the heads stock, not L35's are they???? If L35's ther're non-adjustable, just torque them down to something like 20ft/lbs.

 

[SchnellGhostTy]

Re: Rocker Adjustment Issues...

Stock heads to my knowledge and research. So they have threaded rocker rods?

 

[SchnellGhostTy]

Re: Rocker Adjustment Issues...

I was under the impression that the stock heads have pressed rocker rods and not threaded rods.

 

[Big Mike]

Re: Rocker Adjustment Issues...

You need to step back and read up on how to adjust your valvetrain before you bend or break something when and if it starts. Preload on your lifters depends on what lifters you have stock, comp 850, comp 875, etc.

 

[SchnellGhostTy]

Re: Rocker Adjustment Issues...

You need to step back and read up on how to adjust your valvetrain before you bend or break something when and if it starts. Preload on your lifters depends on what lifters you have stock, comp 850, comp 875, etc.

Stock lifters, like I said the heads are stock minus oversized valves and possibly springs bc I don't know what the previous owner did. Besides that "according to the book" its not working quite right. I have a factory manual in front of me and I can read haha

So let me reiterate I guess...

Should the lifters "leak down" and loose pressure since the engine has already been primed? Even though it seems that some have stayed and continue to seal then when all snugged up while others allow the valve to slightly open maybe a couple have just released pressure sooner than others? I have a feeling that the lifters maybe my problem being that I didn't replace them and litterally replaced everything else in the engine now.

 

[turbodig]

Re: Rocker Adjustment Issues...

Stock lifters, like I said the heads are stock minus oversized valves and possibly springs bc I don't know what the previous owner did. Besides that "according to the book" its not working quite right. I have a factory manual in front of me and I can read haha

So let me reiterate I guess...

Should the lifters "leak down" and loose pressure since the engine has already been primed? Even though it seems that some have stayed and continue to seal then when all snugged up while others allow the valve to slightly open maybe a couple have just released pressure sooner than others? I have a feeling that the lifters maybe my problem being that I didn't replace them and litterally replaced everything else in the engine now.

No.

Once pumped up and bled out, a lifter should stay "hard" for a couple days at least.

I had this problem recently.... most lifters were "stiff", but others kinda mushy on adjust, even after priming with a drill.

Turns out, I had 3, possibly 4 bad *brand-new* lifters. The lifters I replaced them with, had an entirely different casting. I had a persistent lifter "tick" that I couldn't adjust out. It was gone after lifter replacement.

I replaced the right side bank +1 left side lifter, and got the rocker silence I was looking for.

Do *not* automatically trust new rockers. If something doesn't feel right, it's because it isn't.

 

[SchnellGhostTy]

Re: Rocker Adjustment Issues...

Thanks, that is what I was leaning towards in my head. I will prime it again and see if I can duplicate the issues with the couple valves that were doing it as it is now and go from there.

No.

Once pumped up and bled out, a lifter should stay "hard" for a couple days at least.

I had this problem recently.... most lifters were "stiff", but others kinda mushy on adjust, even after priming with a drill.

Turns out, I had 3, possibly 4 bad *brand-new* lifters. The lifters I replaced them with, had an entirely different casting. I had a persistent lifter "tick" that I couldn't adjust out. It was gone after lifter replacement.

I replaced the right side bank +1 left side lifter, and got the rocker silence I was looking for.

Do *not* automatically trust new rockers. If something doesn't feel right, it's because it isn't.

 

[MoJo]

Re: Rocker Adjustment Issues...

Stock Sy/Ty heads have pressed in 3/8"-24 rocker studs that are adjustable and use 20 lb. prevailing torque rocker nuts to hold the preload setting. That is because when using a turbocharger, you don't have to wind the motor into the stratosphere and use bone crushing valve spring pressure to make good power.

Stock aftermarket replacement, GM and Comp Cams 850 hydraulic roller lifters have a preload range from .040" to .060" from zero preload with the roller lifter on the base circle of the camshaft.That is 1 to 1-1/2 turn from zero preload. Never hand pump the lifters full of oil before they are installed in the engine. You will be unable to adjust the preload if the lifters are full of oil. There is just enough lube in the lifters from the factory to prevent them from rusting until they are put into service. .

If you have .raised the valve spring pressure to accommodate a high lift camshaft, you should at least pin the stock pressed in studs or replace them with SB Chevrolet 3/8"-24 screw in studs. Production engine rebuilders pin pressed in rocker studs to prevent "come-backs" even with stock valve springs.

I used GM 12499225 roller lifter package of 16 for the Chevrolet LS-7 V8 engine in my 1991 S10 Blazer 4x4 TBI 4.3L V6 engine with a Comp Cams 09-412-8 camshaft. The GM 12499225 roller lifters set at .060" - .090" preload or 1-1/2 turn to 2-1/4 turns from zero preload. I set the prelaod at .080" or 2 turns. They are the same lifters as GM- 17122490 (AC Delco HL-124) except the GM 12499225 lifter package is half the cost.of the individual packaged GM-17122490 roller lifter.

I am using 1993 L35 CPI heads that came with net-lash screw in rocker studs. I used ARP-100-7201, 3/8-24 x 10mm -1.5 screw in studs that allow the full preload adjustment range. Be advised, not all L35 heads came with screw-in studs so check the rocker studs before you buy a pair.. No problems with my lifter prelaod adjustment doing it the way I described. The engine bay is quiet when idling hot or cold except for the worn out power steering pump. . .I M O
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