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Old 09-23-2009, 06:54 PM   #1
Todd.Brock
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Default Setting Rockers on a Chevy 350

Hey all,

I am helping my neighbor swap out the heads on his 75 corvette. He was only going to swap out the intake and carb. He missed a manifold bolt and pryed the intake out. It broke the head...
Fast forward to a used set of heads now on the car. Can anyone give me advice on how to set the rocker arm tension?? I have a few ideas and want to make sure this is only done once and done correctly. Thanks.
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Old 09-23-2009, 07:02 PM   #2
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Default Re: Setting Rockers on a Chevy 350

I did one a few months ago I Rotated the crankshaft 360º and set the exhaust valves on cylinders, 2, 5, 6, 7 and the intakes on, 3, 4, 6, 8 I tightened each one until each pushrod just got snug and that's it. Also I rotated just until the intake started to move and that's when you adjust the exhaust valve. After they were all adjusted I then turned them all an additional 1/4.

Last edited by djd99; 09-23-2009 at 07:05 PM.
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Old 09-23-2009, 07:11 PM   #3
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Default Re: Setting Rockers on a Chevy 350

The way I was shown is to leave them a little bit loose, fire the motor and tighten until it quiets down. There are little clips that go over where the oil hole is do you don't end up making a HUGE mess. It is still a bit messy though.
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Old 09-23-2009, 07:19 PM   #4
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Default Re: Setting Rockers on a Chevy 350

Adding to what nate379 said:

http://www.lislecorp.com/tool_detail.cfm?detail=570


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Old 09-23-2009, 07:33 PM   #5
Rusty Kustoms
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Default Re: Setting Rockers on a Chevy 350

There are a few ways to do this, the easy and common way is to put the rocker arms on and leave them a tad loose, start the engine and with the valve covers off slowly tighten the rocker nuts until the rockers quiet down.
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Old 09-23-2009, 07:44 PM   #6
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Default Re: Setting Rockers on a Chevy 350

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Originally Posted by djd99 View Post
I did one a few months ago I Rotated the crankshaft 360º and set the exhaust valves on cylinders, 2, 5, 6, 7 and the intakes on, 3, 4, 6, 8 I tightened each one until each pushrod just got snug and that's it. Also I rotated just until the intake started to move and that's when you adjust the exhaust valve. After they were all adjusted I then turned them all an additional 1/4.
sounds right except the 1/4 turn part IIRC it's 3/4 turn but it's been awhile and thats not the only thing i forgot
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Old 09-23-2009, 07:46 PM   #7
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Default Re: Setting Rockers on a Chevy 350

Pre setting them will assure they are not too tight or too loose to allow the engine to start.
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Old 09-23-2009, 08:11 PM   #8
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Default Re: Setting Rockers on a Chevy 350

I hate the running method as oil get all over. I think the non running method is the best.
First look at the exhaust bank on the right side
Have someone turn the crankshaft until you see the intake just begging to open
next tighten ther exhaust valve just until you feel friction
do this on all exhaust valves on the right bank and repeat this on the left bank
Then do the intake valve turn the motor 360 \until you see the exhaust valve open then stop and tighten the intake valve until you feel friction then repeat on left bank
Of course this is very easy with the spark plugs out.
When your all done I belive it's give all them 1/2 turn and you should be good to go.
No mess and as far as I'm concerned I'll never do it another way.
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Old 09-23-2009, 08:34 PM   #9
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Default Re: Setting Rockers on a Chevy 350

Basically, everyone has said roughly the same thing. If you rotate the engine a few times you will see when the valves are closed and which ones are open. The point about leaving them a little loose is mostly important if you have brand new lifters (I think all of us assume that you have hydraulic lifters). Leaving them a little loose allows compensation as the lifter fills completely with oil. Then, after you get them running you can tighten as necessary to take up the slack.
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Old 09-23-2009, 08:44 PM   #10
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Default Re: Setting Rockers on a Chevy 350

Just slap solid lifters in it and you will be a pro in no time flat....................lol
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Old 09-23-2009, 08:52 PM   #11
Todd.Brock
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Default Re: Setting Rockers on a Chevy 350

Thanks for all the help guys! I will give it a shot and let you know how it turned out.
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Old 09-24-2009, 12:46 AM   #12
Charles (in GA)
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Default Re: Setting Rockers on a Chevy 350

My 1972 Chevy factory manual gives the following info.

Crank engine until mark on torsional damper lines up with center of "O" mark on the timing tab and the engine is in number 1 firing position. This may be determined by placing fingers on the number 1 cylinder valve as the mark on the damper comes near the "O" mark on the front cover. If the valves are not moving, the engine is in the number 1 firing position. If the valves move as the mark comes up to the timing tab, the engine is in the number 6 firing position and crankshaft should be rotated one more revolution to reach the number 1 position.

Valve adjustment is made by backing off the adjusting nut (rocker arm stud nut) until there is play in the push rod and then tighten nut to just remove all push rod to rocker arm clearance. This may be determined by rotating push rod with fingers as the nut is tightened. When push rod does not readily move in relation to the rocker arm, the clearance has been eliminated. The adjusting nut should then be tightened an additional 1 turn to place the hydraulic lifter plunger in the center of its travel. No other adjustment is required.

With engine in number 1 firing position as determined above, the following valves many be adjusted.

Exhaust - 1,3,4,8
Intake - 1,2,5,7

Crank the engine one revolution until the pointer "O" mark and torsional damper mark are again in alignment. This is the number 6 firing position. With the engine in this position the following valve may be adjusted.

Exhaust - 2,5,6,7
Intake - 3,4,6,8


The mechanical tappet setting is easy, use a socket and feeler gauge and a set of oil deflector clips, and run the engine (hot) and set the clearance. Intake .024" and Exhaust .030".

Charles
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Old 09-24-2009, 12:56 AM   #13
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Default Re: Setting Rockers on a Chevy 350

I have NEVER set the valves on a sbc with the engine running, just me. I usually use aftermarket roller rockers, no turn after zero lash, for most aftermarket arms.

Use the already explained non-running procedure, once there is no up and down play in the push rod, roll the push rod between your fingers, you will notice when you do the 1/2 to 3/4 turn after zero lash, the push rod will be lightly snug, and turnable with a little pressure. Perfect! No need to go back,after it runs, once you get the hang of it. Err on the slightly loose side, too tight will slightly push the valve off its seat, just enough to cause trouble. good luck

If you are adjusting the rockers with new lifters, I pump the lifters up first, or be carefull not to press the tappet to the bottom of the lifter body if dry, this will result in a too tight adjustment, once the hydraulic lifter operates.
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Old 09-24-2009, 12:56 AM   #14
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Default Re: Setting Rockers on a Chevy 350

I set them with the engine running, I have a valve cover i plasma cut the centers out of so it stops the oil from spraying everywhere.
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Old 09-24-2009, 07:54 AM   #15
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Default Re: Setting Rockers on a Chevy 350

Quote:
Originally Posted by J.A.F.E. View Post
Adding to what nate379 said:

http://www.lislecorp.com/tool_detail.cfm?detail=570


Image hotlinked from above Lisle page.
These are pieces of junk IMHO. The stamped steel ones work A LOT better. Try to find them if you can.

I agree with Jared, get an old valve cover and cut out the center works alot better; everything stays lubed.
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Old 09-24-2009, 08:22 AM   #16
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Default Re: Setting Rockers on a Chevy 350

use valve overlap method
1 8 4 3 6 5 7 2

1843
6572

to ensure you are at tdc for #1, watch the companion cyl valves for overlap which would be cyl 6..........when ex is just about closed and intake begins to open you know you are on tdc # 1 ........then watch #5 and set 8, 7/4, 2/3, 1/6, 8/5, etc.....works for all even number cylinder engs..........3 and 5 , weel on your own...........i usually do half a turn to 5/8..........no more than 3/4...........on my own i usually try to rest the valves after a monthe or so..........
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Old 09-24-2009, 01:53 PM   #17
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Default Re: Setting Rockers on a Chevy 350

Plenty of good answers here so I'll jsut supply an anticdote about adjusting lifters:

Back in high school (before intelligence set in), i was helping a buddy put a 283 SBC in a '84 camaro. The old 283 enginer manual his stepdad had told me to tighten the rockers until no play in the pushrods. I did so.

Fast forward 2 weeks later when we cranked it up for the first time, it just backfired and popped. After fiddling with the ignition and starter for 6 hours, we pulled a spark plug to check compression and it read 20 psi while cranking!! We knew then that the overtightened rockers kept the valves open all the time- no compression could build at all. Loosened them up and 20 min later we were doing burnouts in the street. Stupid kids...
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Old 09-24-2009, 11:30 PM   #18
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Default Re: Setting Rockers on a Chevy 350

You already have the answer, but here is my contribution.

First get an old valve cover and cut the top along intake manifold long side a both ends. Turn this flap to be straight up. Now you have a open top valve cover that will keep oil splash inside the valve cover.

Second, i like to set mine with engine running. with engine idling, loosen until it clacks, then tighten until zero lash quiet, and go additional 1/2 turn. Because this way you are sure that all of the lifters are set equally. The engine will run noticeably smoother when all the valves are set equal.

For new cam or head swap or occasion where you need to se them initially, the rotate until they get tight and then 1/2 turn method works. But I still reset them hot with engine running once it is all running.

BTW, on my Pontiac, I use poly locks and adjust the valves "Chevy style" instead of just tighten the nut until it bottoms out as in the factory design.
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Old 09-28-2009, 11:05 AM   #19
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Default Re: Setting Rockers on a Chevy 350

I was watching one of the old episodes of classic car restoration on TV and seen him set valve a different way than I have every done it. after getting the valve in the correct postion on the cam lobe he took a Tee handle I believe and tightened down adjustment nut unit the valve spring started to compress which meant the lifter was fully compressed then he slowly loosened the nut while watching the valve spring when it stopped uncompressing he then lossened another 1/2 to 3/4 turn to put lifter in the middle of it travel.

Havent tried it yet but will next time to me it looks like it takes the "feel" out of it. JMO
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