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Discussion Starter · #1 ·
Just adjusted the valves on my 350. Started at cylinder #1 at TDC on the compression side. Adjusted that cylinder then moved crank 90 degrees then adjusted cylinder #8 then moved crank 90 degrees then next cylinder in firing order did this until all valves where adjusted. My question is when setting the lifter preload some of the rocker arm nuts
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would only tighten 1/2 a turn all the way and some would go 3/4 of a turn. Will this be an issue later on. Some guys on another site say 1/2 turn is ok. Also with type of rocker nuts I have they say have to adjust the sets screws. What should I do ? Picture us of one of the rocker arms and nuts.
 

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Are you saying that your nuts were bottomed out on the studs so that there was no way to tighten them further? If so, something is wrong. You should have lots of adjustment room there. From that camera angle those LOOK to be the type that uses a center set screw.
 

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I know the service manual says 1 turn after the rocker arm contacts the pushrod, but it's been common for years to set 'em about 1/2 turn to extend the rpm range a bit. I've done the 1/2 turn on many SBC's for many years without any issues. I've never seen or used that type of nut, but I've done the same specs on various billet and roller rockers, again without issues.

Bill
 

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Just adjusted the valves on my 350. Started at cylinder #1 at TDC on the compression side. Adjusted that cylinder then moved crank 90 degrees then adjusted cylinder #8 then moved crank 90 degrees then next cylinder in firing order did this until all valves where adjusted. My question is when setting the lifter preload some of the rocker arm nuts View attachment 139417 would only tighten 1/2 a turn all the way and some would go 3/4 of a turn. Will this be an issue later on. Some guys on another site say 1/2 turn is ok. Also with type of rocker nuts I have they say have to adjust the sets screws. What should I do ? Picture us of one of the rocker arms and nuts.
"would only tighten 1/2 a turn all the way and some would go 3/4 of a turn."
That makes no sense. Are you loosening the lock nut inside the adjusting nut and backing off the adjusting nut until you can spin the pushrod before you try to set the lash at 1/2 turn? There's nothing wrong with 1/2 turn but if you can only turn the adjusting nut 1/2 turn you are doing something wrong or you have some collapsed lifters.
 

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Loosen nut, back out center lock 1 turn, then tighten nut while spinning push rod with your fingers, when you feel resistance then go 1/2 to 3/4 turn from that point, tighten center lock. I use a clear distributor cap so I can do the valves in the firing order when both valves for each cylinder are closed. Hard to make a mistake with this method.
 

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as a check ; All nuts should end up at the same height, put a straight edge across the tops and look for any gap. Every cylinder should be the same, whether its piston weight, valve seat width, plug gap or rocker arm stud.
More than .020" - i would check the stud height without nuts on & same method. if a stud is pulled it'll show up this way.
When finding zero lash wiggle push rod sideways instead of up & down, just get close, you can feel it n the rocker. i've had alot of mechanics goto far and bottom the lifters out.
Add 1/2 turn. its done. i run the high volume oil pump, so for my engines i go with 1/4 turn, and thats still way more oil pumping thru pushrods than needed.
From GM service Manual;
#1 at TDC you can adjust exhaust 1,3,4,8 & intake 1,2,5,7

rotate 360 degrees #6 at TDC adjust exhaust 2,5,6,7 & intake 3,4,6,8

This applies to any chevy engine with standard firing order 18436572 , small or big block!
 

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That nut looks a bit fancy and without a picture from the top, it is hard to make a definitive determination if this is a locking type nut. If you can see an allen head screw inside the nut, you have a locking rocker nut. When setting valve lash with these type nuts, they require additional steps.

Basically, once you've determined the cylinder is at TDC, back off both the outer nut as well as the inner set screw; be sure the set screw is backed off sufficiently to not hamper tightening the outer nut. Next, tighten the outer nut until you are not able to spin the pushrod with your finger tips, then apply your additional 1/2 or 3/4 turn of the outer nut. Now, tighten the inner set screw. Repeat these steps for each rocker arm.
 

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When I changes my rockers and lifters my new roller rockers came with the same type of nut. I ended up having to order different size pushrods. Make sure the center lock is backed out (as stated previously). If it is and the nut is bottomed out, I recommend measuring for required pushrod legnth.
 

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Good luck.............
 

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I'm confused as to why you're using those nuts on stamped steel rockers. I've only used those locknuts on roller rockers. Find the stock style nuts to use on stock rockers...might fix your problem... and follow Proton's advise on the adjustment. That's the way I've always done it. It works and it saves A LOT of time.
 

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Discussion Starter · #11 ·
Went back and loosened the sets screws and readjusted all the valves and tighten the set screws when adjusting each individual valve. Set the preload at 1/2 turn. That type of nut and rocker arm is what the engine had on it when I bought it. Originally had a roller cam in it. This is a budget type rebuild. Any good suggestions for a good break on oil. Would Rotella T4 15w40 be good. Could it be used as the regular oil also. Some say yes others say no.

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Trainfan, what did you do with your rebuild? If you did not install new piston rings or bearings, etc., why are you going through a break-in? As for what oil to run in your motor, 10W40 is as good as any all around oil.
 

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Discussion Starter · #13 ·
Trainfan, what did you do with your rebuild? If you did not install new piston rings or bearings, etc., why are you going through a break-in? As for what oil to run in your motor, 10W40 is as good as any all around oil.
Has new bearings and piston rings.
 

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In that case, yes, it needs to be broken in. I have Torco break-in oil in my newly rebuilt 350. As far as Rotella, sorry, I have no idea what oil that is.
 
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