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Adjusting rocker arms. 350ci

 
starkiller
I love my Chevy Chevette!
Posts: 8
Joined: 11/11
Posted: 12/30/11 03:05 PM

Okay I rebuilt it, stuck it in, tried to set the rockers close to how it was before I took it apart. Now I've got it in, driven it a little, I'm trying to adjust the rockers. I've heard you warm the engine, remove valve covers & plugs, and turn the engine over until each piston is at TDC, then tighten the rockers until you can just barely turn the pushrods with your hand. Is this the best way? I was thinking I leave the plugs in it, warm it up and remove the valve covers, and keep bumping the engine over, tightening the rockers until none of them are excessively loose.  

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skyeking
I mow my lawn and find Chevys
Posts: 2738
Joined: 08/09
Posted: 12/30/11 03:47 PM

Hi there,
When the motor is mildly warm tighten to just firm
with no free play then wind spanner
off 1/2 turn or 180*. Never failed for me.
Stock hydraulic lifters even when noisy at cold will
compensate over 30/1000" wiyhout loss to performance,
better a fraction loose at idle than tight..
Good luck and all the best....Skyeking.  
skyeking

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starkiller
I love my Chevy Chevette!
Posts: 8
Joined: 11/11
Posted: 12/30/11 04:41 PM

Okay I just got done tightening them to the suggestion I found when searching this forum for rocker adjustment.

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roll the engine clockwise with a wrench until #1 is in the fire position, note the #1  rocker arm movement as you turn it to be sure it's the #1 mark on the balancer. if the rockers move when your bringing the timing mark up, it's on #6.   when you have #1 at TDC, you can adjust :

  exhaust #1, #3, #4 & #8

  intake #1, #2, #5 & #7

now rotate the engine one revolution until the timing mark is on TDC for #6, now adjust:

   exhaust #2, #5, #6 & #7

   intake #3, #4, #6 & #8

as you tighten the rocker nut, roll the pushrod with your fingers. at the first feel of drag, note nut position and tighten 3/4 of a turn more. this will give it the recomended preload for GM lifters. some lifter makers want a different preload, always follow their specs.  
_____________________________________________________________

I did this above, and the truck sounds worse than before. You say to back them off a half turn after the pushrod gets tight? It says tighten them another 3/4 turn after they begin getting tight, maybe I pop the valve covers AGAIN and back them all off a full turn.  

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BuzzLOL
I have an SS396 tatoo
Posts: 380
Joined: 12/10
Posted: 12/31/11 02:21 AM

.. It's usually hard to feel when the slack is out by twirling the pushrods... better to jiggle them up and down and when the last click is out of them, give them another 1/2 - 1 turn tighter... like 1 turn for stock engines... 1/2 turn for performance engines to limit the amount the lifter can overpump up at highest RPMs...  

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idrivejunk
I mow my lawn and find Chevys
Posts: 5119
Joined: 12/09
Posted: 12/31/11 07:33 AM

+1 Buzz. Wiggling up and down works better for me. Lock it at a half turn past zero lash.  
idrivejunk

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starkiller
I love my Chevy Chevette!
Posts: 8
Joined: 11/11
Posted: 01/01/12 01:47 PM

Can I do this while the engine is cold or should I warm it up first?  

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76Skylark
Big Block power for the win
Posts: 868
Joined: 12/11
Posted: 01/02/12 07:59 AM

it can be cold the Idea is to get the lifters full of oil,but a warm engine is better.I take my time and do 1 cylinder at a time.I also do it with the plugs out and use a piece of Straw to find TDC of each cylinder,when the engine is out you can use a lite to see the piston..the best but MESSY way is with the engine running.Lots of rags,we use a Valve cover with the top cut out.with Engine Idling back off a rocker till you hear it clatter...tighten till it just Stops making a loud clatter then turn 1/2 turn more.just start at one end and work to the other.It's a mess but you won't have to go back again after that.  

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Pontiacman2
Moderator
Posts: 8956
Joined: 09/08
Posted: 01/02/12 10:28 AM

+1 lark

I set mine at a 1/4-1/2 turn of pre load is all that is need I have seem problems with more then that.  
Pontiacman2
Pontiacman2

Professional Hi-performance engine builder

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frotosride
My first time was in a Chevy
Posts: 162
Joined: 02/10
Posted: 01/03/12 03:40 PM

Wink If you are positive that you tightened the rockers on the base circle and completly off the lobe ramp then you may be looking at a diffrent beast causing these unwanted noises. When you say sounds worse than befor do you mean the valvetrain is chattering or the exhaust notes are rough... if exhaust i would check and reck timing especially since you said you just rebuilt... just a thought.my 2sence(-)tax  
"Beat it like a red-headed FORD"

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
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Posted: 01/03/12 03:58 PM

Starkiller:

Yeah it sounds like you have some tight lifters! Confused
Thanks
Bob  

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starkiller
I love my Chevy Chevette!
Posts: 8
Joined: 11/11
Posted: 01/11/12 04:53 AM

It was rattling under the valve covers and popping out the exhaust a little. I tightened some of the rockers and it stopped rattling under the hood but the exhaust popping is in the exact same rhythm as before. So I believe I have 3 exhaust too tight.

My problem now, is if I loosen rockers after I warm the engine, does the lifter pop up, or does it stay compressed? If it stays compressed it means I'll have to go through loosening every rocker, run the engine and retightening them. If not, then I should be able to loosen them and have it right the first time. I am so annoyed with this thing, Help please.  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 01/11/12 11:46 AM

If you can see the lifter is colapsed you will have to remove the intake manifold and replace the lifters that are colapsed. Just hope you didn't damage the cam and/or lifter bores.

Did you use just a replacement rocker arm. (No roller rockers) Some of them are thicker then the oe type,and when you start the engine the rocker arm hits the valve cover. So if this is what happened and then you tightened down the rocker arm thinking that was the noise. You would eventually bottom the lifter and the engine would pop back through the carb or the exhaust.

Everyone that answered you(each in a different way but the out come is the same it will still get you there) gave you the correct way to adjust the rocker arms. Each time you spin that adjusting nut one turn in you are adjusting the lifter nearly .100 of an inch down. Then don't forget the internal parts of the hydraulic valve lifter.Those parts all come together causing (known as stack up tolerances).

If you haven't fixed your problem as of yet. I would suggest removing the intake manifold and check each and every lifter bore and cam lobe for any damage.Replace any all damaged lifters ie. any lifter that colapsed is now  junk it won't pump up correctly. It also could break because if it was colapsed it maybe fractured internally were the hydraulic pressure is at it's greatest.(DON'T REUSE THEM).
Thanks
Bob  

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skyeking
I mow my lawn and find Chevys
Posts: 2738
Joined: 08/09
Posted: 01/11/12 03:48 PM

Well said Lemonade dodger...  
skyeking

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starkiller
I love my Chevy Chevette!
Posts: 8
Joined: 11/11
Posted: 01/11/12 08:09 PM

I don't think I tightened them so excessively that the lifters are damaged. I meant that the lifter fill with oil when the engine is warmed up, and at that time the rocker arms would be at their tightest. But for ones I have too tight, when I loosen them, the lifter will not open up will it, expanding to how it should be when warm, so that I can tighten them correctly. Won't they just stay wherever they're at when I loosen the overtightened rockers and I have to run the engine some more before tightening them?  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 01/12/12 03:11 AM

Thank you Mr. Skyeking Grin  Cool
Bob  

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