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Old 08-21-2008, 10:38 AM
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Adjusting olds rockers .... HELP

Adjusting olds rockers

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I need to readjust the rockers on my sons 1970 olds cutlass with an 350 engine, he has roller rockers with an hydraulic cam he just had the motor rebuilt not too long ago and the rockers are getting a little noisy , the machincist said to use this procdure not to do it when the motor is running , just seems that you have to turn the motor over a thousand times to do this, is there another way? thanks for any info.

How to adjust valves on a chevy smallblock
There are a several methods for a valve adjustment on a chevy small block engine. Everyone seems to have a valve adjustment method they are most comfortable with and some of them will work well, but some are an inaccurate valve adjustment method. Even GM recommends doing the valve adjustment while the engine is running, which I won't teach you because it makes a tremendous mess.

You are going to learn how to do the valve adjustment, or more appropriately, adjust the lash or clearance between the rocker arms and the head of the valve stems using a method that will work for all 4 stroke internal combustion engines. The only difference between engine makes and models would be the details such as the number of turns after you have reached a zero lash, or in the case of solid lifters, the lash setting.

First consider that there is a relationship between the high position on each cam lobe for each cylinder respective of which stroke the cylinder happens to be in. We are going to adjust each valve at a time relative to the position of its peer valve ( or cam lobe ), either the intake or exhaust. This method insures the cam lobe for the valve you are adjusting is directly opposite the valve lifter and there is no measure of lift acting on the valve train components .

To do the valve adjustment you will need to crank the engine over in the same direction it would turn if it were running. If the engine is not in the vehicle you can turn the flywheel, or if it is in the vehicle you can use a remote starter button.

You will do the intake valve adjustment as the exhaust valve is just opening and you do the exhaust valve adjustment as the intake valve is almost closed. You might need to say that quite a few times to memorize it.

Here are step by step instructions:

Remove the valve cover.

Identify the number one cylinder. See the page on Firing Order on the menu to the right if you are not sure which cylinder is number one.

Turn the engine over until you see the number one cylinder exhaust valve rocker arm JUST START to move from the closed position to open. You may need to turn the motor over a couple of times to reach this point, but do not turn any further.

Locate the intake valve.

Loosen the rocker arm adjustment nut until you feel some obvious lash or clearance in the adjustment.

Using the thumb and index finger of one hand, grasp the intake push rod below the rocker arm, and rotate it back and forth (clock-wise and counter clock-wise successively to be sure there is no remaining pressure on the push rod from the rocker arm as you loosen the rocker arm adjusting nut.

Using the other hand, while continuously performing step 6, with a 5/8 socket and ratchet, tighten the rocker arm adjustment nut slowly until you feel a resistance of motion on the push rod.

This will be the zero lash adjustment point. For hydraulic lifters, tighten the rocker arm adjustment nut 1/4 - 1/2 of a turn. For solid lifters, back off the rocker arm adjustment nut until your feeler gauge just fits under the contact point between the valve stem and the rocker arm. Fine tune the adjustment by checking it with a feeler gauge just slightly thicker than the preferred clearance to be sure the clearance is not greater than it should be. If the larger feeler gauge will fit, it needs to be re-adjusted. A lash tolerance of 1-2 thousandths of an inch in the valve adjustment for solid lifters would be acceptable since it may be difficult for someone who is in-experienced to be more precise than that.

Turn the engine over until the intake valve opens and then is almost closed.

On the exhaust valve, repeat steps 5 through 8 for the exhaust valve adjustment.

Repeat this procedure for each cylinder. Be sure to do each cylinder sequentially, either following the firing order, following the cylinders numerically, or in the case of a V8 doing one side of the engine at a time. I prefer to do one side of the engine at a time.
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Will this method work on 1970 Olds 350?

Small Block Chevy Valve Adjustment Order

0 deg TDC, both number one valves shut.

both intake and exhaust on the number one cylinder are closed.

Adjust the #1 exhaust valve

Adjust the #1 intake valve

Adjust the #3 exhaust valve

Adjust the #5 intake valve

Adjust the #7 intake valve
Adjust the #2 intake valve
Adjust the #4 exhaust valve
Adjust the #8 exhaust valve
Now rotate the engine 360 degrees. The mark on the balancer should be back at the TDC mark. Keep in mind that this is not the TDC where #1 would be firing! It's where #6 would fire.

both the intake and exhaust of number 6 cylinder are closed.

Adjust the #3 intake valve
Adjust the #5 exhaust valve
Adjust the #7 exhaust valve
Adjust the #2 exhaust valve
Adjust the #4 intake valve
Adjust the #6 exhaust valve
Adjust the #6 intake valve
Adjust the #8 intake valve

again, hold the push rod between finger and thumb, twist the push rod, tighten the rocker arm nut, when you start to feel resistance, when the push rod gets hard to easily turn with your finger and thumb, that's when you give the rocker nut a 1/4 turn and STOP ! that valve is now adjusted, move to the next one and repeat, until you have done all 16 of em

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Old 08-21-2008, 10:47 AM
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If you post the type of cam, hydraulic, or solid, and what the lift is, it will be easier to say how to adjust the valves.
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Old 08-21-2008, 10:51 AM
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Quote:
Originally Posted by Denny
If you post the type of cam, hydraulic, or solid, and what the lift is, it will be easier to say how to adjust the valves.
HI i say it had a hydraulic cam
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Old 08-21-2008, 10:58 AM
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Quote:
Originally Posted by A/G WILLYS
HI i say it had a hydraulic cam
Ok, but you didn't mention the lift ? If it's under .500, you can adjust them much easier.
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Old 08-21-2008, 11:20 AM
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Quote:
Originally Posted by Denny
Ok, but you didn't mention the lift ? If it's under .500, you can adjust them much easier.
Do tell inquiring minds want to know.
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Old 08-21-2008, 11:36 AM
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Old 08-21-2008, 11:37 AM
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Quote:
Originally Posted by Denny
Ok, but you didn't mention the lift ? If it's under .500, you can adjust them much easier.
yes it is under .500
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Old 08-21-2008, 11:38 AM
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yes we have installed aftermarket adjustable rockers,
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Old 08-21-2008, 11:40 AM
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The above procedure is fine for OEM stock cams, but for anything else you would want to use the following:

A. Starting with #1 cylinder, turn the engine over until the exhaust pushrod just begins to move up.

B. At this point, stop and adjust the intake valve on the same cylinder.

1) Tighten the rocker until you can roll the pushrod between your thumb and forefinger with the slightest bit of resistance.

2) At this point tighten between an additional quarter to half of a turn.

C. You have now adjusted the #1 intake valve. You will now want to turn the engine over while watching the same intake pushrod that you just set, it will go full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. By following this procedure, you are assured that both of the lifters are at the base circle of the cam and that there is no additional pre-load applied to them from cam lift at this point.

D. You are now able to repeat this procedure on the remaining cylinders.

4.Re-install your valve covers and your valve adjustment procedure is finished


On edit: OOPS! You already posted that. Yes, use that procedure.
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Old 08-21-2008, 12:22 PM
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That is all well but, I use the point where there is zero lash at the rocker arm instead of the "twist the pushrod" method.
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