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Old 08-19-2011, 02:47 PM
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I need help adjusting valves in a small block chevy 350

I have tried to adjust valves using the multi adjusmentmethod but some rockers end up really lose is this normal

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Old 08-19-2011, 03:37 PM
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Originally Posted by Sjh1996
I have tried to adjust valves using the multi adjusmentmethod but some rockers end up really lose is this normal
Do a search here and you will find several threads with the information you need. You also will get better answers if you post engine questions in teh engine forum.
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Old 08-22-2011, 08:14 AM
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G'day Sjh1996.

I have looked in the engine tech section to see if you have posted in there, but could not find anything ?. So if you have posted in there, please forgive my answer here. You may already have an answer to your problem.

Your question is a bit vague so I will do my best to second guess.

I'm guessing that this motor is a V8, and a Chev SB and has a Hydraulic Cam and was/is a runner, not a brand new built motor that has never been started ?. If so we can proceed.

If the motor is brand new, never been started then you should seek out somebody who knows how to setup and "break in" a new motor. The first 20 minutes running are CRITICAL.

OK, so your motor needs a valve adjustment. Why ?. This could be because of wear issues, wrong oil, high mileage etc.etc.

Lets set your rockers. Note we will NOT be running the motor for the initial setup.

(1) Pull the rocker covers.

(2) Remove Sparkplugs.

(3) Rotate motor in normal direction to TDC (not backwards at anytime)
Whilst rotating motor observe the Rockers on number one (1). When you approach TDC check that both pushrods on number one (1)are level in the down position. This indicates that the lifters are on the base circle of the cam and both valves should be closed on compression stroke. If you have a helper they can place there finger over the sparkplug hole and check for air pressure pushing on the finger, indicating TDC.

If you are 180 degrees out, the pushrods on number one (1) will be "rockin" as mechanics call it. That is one pushrod will be up (valve open) the other down (valve closed). Number six (6) will be in TDC position. This situation is the classic 180 degrees out of time distributor issue that you may hear about.

(4) Adjust both valves at number one (1) to the Specified preload or valve lash if a mechanical lifter motor.

(5) Now check all the pushrods on each side of the motor and observe which are up (valve open) or down (valve closed). Grab the pushrod between your fingers, if you can rotate it, it's a fair bet that the pushrod is down or valve closed position.

Adjust all of the rockerarms on the pushrods that are down (valve closed) to the "specified preload" You can mark the pushrods if you like with a permanent marker pen or white paint marker so you can visually see where the pushrods are in the up and down movement.

(6)Rotate the motor a 1/4 turn. Repeat checking the pushrods as above and adjust the rockerarm preload/lash to the "specified preload"

(7) Repeat the process again until you have completed 2 turns of the crankshaft, coming back to TDC on number one (1).

(8) If unsure then repeat the exercise. No shame in being doubly sure. What you can do is a light preload on all valves first, say 1/4 turn from zero lash going through the above method. Then when you are happy all is right, do it again to the specified preload.

Generally preload on a Chevy SB is 3/4 of a turn on the rockerarm nut from contact of the rockerarm tip at the valve stem face.

This is a quick and "dirty" mechanics way to do it. Mark the Rockers if you like with chalk or marking pen so that you know you have set the preload on that valve.

If the motor gets tight or really stiff while turning over STOP. Check out why and fix it or relash the valve. It is real easy to bend pushrods. Also when pushrods are loose they can come out of the lifter and rocker arm, so keep your eyes peeled for problems and make sure they are located before preload.

The preload sequence instructions in manuals are there for a reason, so that you don't miss anything.

Now after you have set the preload and you are happy all is correct, give the rockers a good dose of oil and button it up. Now it's start time.

Turn it over and let the motor warm up, no big revs, keep rpm below 2000. Look for oil leaks and listen for any suspicious rattles, engine misfires. If any rockers/lifters start to tick during warm up or when hot then mark the approximate position on the rocker cover where the tick is coming from. Stop the motor. Pull the Rocker Covers and check those valves for loose Rocker retaining nuts or incorrect preload at that valve.

You can buy (or make yourself) special rocker covers which allow adjustment of the rockerarms with the motor running. These covers are cut away to allow access to the rocker arm nuts but still cover the oil hole on the rocker arm so as to deflect the oil and keep most of the oil back into the head. They sort of work, but you still get some oil splashing, usually onto the paintwork, chrome and headers.

If the problem with ticking or loose rockers appears again after resetting, then it might be time for new Rocker Arm nuts.

Hope this helps.............Barry.
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Old 08-22-2011, 12:52 PM
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Quote:
Originally Posted by Sjh1996
I have tried to adjust valves using the multi adjusmentmethod but some rockers end up really lose is this normal
solid or hydralic lifters?
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Old 08-22-2011, 10:33 PM
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depending on the cam you have, if it has alot of overlap, 106-110 lobe angle setting the piston to TDC then adjusting your valves is a bad idea because of the over lap in the cam imo. some vlaves may be tight, others may be real loose this way. you might be ale to get by with it on a stock cam with a high lobe angle cam like 114-116 range.. I like to use the E.O.I.C method.. Exhaust Open Intake Close method..
Start by taking all your plugs out, make the carbrator open at WOT, this allows the motor to breath and turn over easy.. You want to adjust each valve seperatly on each cylinder.. turn the motor over by hand untill the Exhaust valve starts to open, then adjust your intake valve.. the then rotate engine so that the intake valve is is closing but not all the way up, then adjust the Exhaust valve.. E.O.I.C this method I fine is the best most consistant way to adjust the valves..
hope this helps
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