Easiest way to adjust valve zero lash?

[Blown1993Z28]

I just finished installing some polished aluminum Valve Covers. While I had it opened I checked the play in the pushrods. Not only did 1/2 of the pushrods spin freely, there was about 1/16" of up and down play. I am assuming that play means my valves never open fully. I've read a couple different ways of setting the preload and am wondering which is the easiest. I got this from shbox.com

Method 1

If you have never had the crank hub off (or know for sure that it's orientation is correct), you can use the arrow that is on the balancer to tell you where you are. You don't have to spin the crank every 90º with this method.

When the arrow is at 12 o'clock you will be at either #1 or #6 TDC. You might have trouble identifying whether #1 or #6 is at TDC when the crank arrow is at 12 o'clock. Probably the easiest way is to look over the other valves or lifter positions. Compare them to the charts below, showing which can be adjusted. Any valve that can be adjusted should be UP (closed) and the lifter/pushrod should be down. Valves that are not to be adjusted will be in varying d ees of being open or DOWN (lifters/pushrods UP). I used to recommend looking at the valves on the #1 and #6 cylinders, but sometimes it can be difficult to tell by those cylinders only. After looking at the charts below and your valves or lifters/pushrods, you should have it figured out rather quickly.

Valvetrain Movement Reference Diagram

When at #1 TDC you can adjust the following valves:

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

Rotate the crank one revolution until the pointer is again at 12 o'clock. This will let you adjust the remainder of the valves. If you did #1 the previous time, you should be now at #6 TDC.

When at #6 TDC you can adjust the following valves:

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

I am assuming that you need at least a 1/2" breaker bar to spin the motor one revolution. There is also a lot of disagreement about how much preload to apply. 1/2 a turn seems to be the average.

Would getting some 1.6 RRs make this easier or harder?
Also is it normal for my valve train to be out of whack like this? (75,000 mi.)
Last, does this play in the pushrods mean my Valve Springs are worn out? I will propably get at least LT4 springs if I get the 1.6RRs.

[Badazz 97 T/A]

honestly use whatever way you feel more comfortable doing. i tried both ways you posted and i like doing it the first way personally. for whatever reason i always messed up doing it the second way.

but both methods will get the job done. There always gonna be some play in the rockers. there never going to be super tight unless there is pressure on the valve spring. the lifters bleed down when the engine isnt running. so take that into consideration.

adjusting valves is adjusting valves. Doesnt matter what type of rockers you have unless you have some solid rollers or whatever. If your using stock lifters and rockers do around 3/4 turn preload.

[Tony]

Zero lash is just that the rockers have no gap between them and the valve. On a hydrolic motor, you set to zero lash, then go 1/4 to 1/2 turn past. I have always went 1/4, but that is just me.

The ratio of the rockers that you use will not make it easier or harder. They are there only to open the valve a little more. You will need new pushrods and if you get NSA's, you will need to install guide plates.

If there was that much play, then something is getting worn out. If your oil pump is still working okay, you should still be able to spin the pushrods, but they should have no up and down movement by hand. There should be a constant preload on them from the lifter. The ones that you were feeling that was really tight, are you sure that the cam was not pushing the valve open?

Your valve springs have nothing to do with it. When they wear out, they usually break and if that happens, you are prolly looking at a new motor when that valve goes into the motor.

If you are wanting to get a bigger cam in the future, do your self a favor and just get the Comp 918 springs. That way you can run any cam you want and never have to worry about the springs again.

[Blown1993Z28]

Originally Posted by Tony

Zero lash is just that the rockers have no gap between them and the valve. On a hydrolic motor, you set to zero lash, then go 1/4 to 1/2 turn past. I have always went 1/4, but that is just me.

Originally Posted by Tony

The ratio of the rockers that you use will not make it easier or harder. They are there only to open the valve a little more. You will need new pushrods and if you get NSA's, you will need to install guide plates.

If there was that much play, then something is getting worn out. If your oil pump is still working okay, you should still be able to spin the pushrods, but they should have no up and down movement by hand. There should be a constant preload on them from the lifter. The ones that you were feeling that was really tight, are you sure that the cam was not pushing the valve open?

Your valve springs have nothing to do with it. When they wear out, they usually break and if that happens, you are prolly looking at a new motor when that valve goes into the motor.

If you are wanting to get a bigger cam in the future, do your self a favor and just get the Comp 918 springs. That way you can run any cam you want and never have to worry about the springs again.

According to shbox.com, you can adjust 1/2 of the valves at a time. The really tight half were in various stages of valve lift while the other half had the play in them. I am assuming after turning the motor one full rotation all the previously tight ones would be loose as well and require adjustment. I've never turned a V8 by hand. I am guessing a 1/2" breaker bar on the crank pulley would be able to turn it with the spark plugs still in?

I've heard the 1.6 RRs are a great upgrade, but it's sounding like a lot of money and work for little HP gains. Here are the RRs I am looking at;
Proform Parts 66915 - Proform Extruded Aluminum Roller Rocker Arms - Overview - SummitRacing.com
Even if these are self aligning, adding the cost of new springs and new pushrods is scaring me away. There are a lot of different pushrod options. How do I tell what I need? I am leaning towards just adjusting my 1.5 stamped steel rockers and waiting until I get the heads ported to do the rest of the upgrades.

P.S. I am going to set my preload like I order my steaks, Medium. If the good range is 1/4 turn to 1/2 turn I will go 3/8 turn. While tuning RF electronics we usually had a minimum and maximum limit. I always aimed at the middle figuring I would have some cushion either way. Hopefully the 3/8 turn comes out the same, not too loose but not too tight. This sounds like a critical adjustment and I don't want to screw it up.

[Tony]

You will know if you have them too tight or too loose. Too tight and you will hear the motor bog down. If you leave it like this, you will loose power and wear things out really fast. If you have them too loose then they make a crap load of noise lol.

Yes, Robs site is correct, you can adjust 8 valves at #1TDC and the other 8 valves at #6 TDC. I can spin my motor over with a 12" ratchet, so you shouldnt have any problem with a breaker bar.

As for the cost scaring you away, You need to think about something. RR's will net you about 15hp. The 1.6:1 over the 1.5:1 will net you a little more. BUT!!! You are running boost!!! With the right cam, you will gain even more than that cause you have air being forced into the motor. So, you can logiclly gain about 35hp just by putting on 1.6:1 RR's with 4.5lbs of boost. According to your sig, you don't have headers.... If you put some LT's on your car, you will gain more than that. Your getting the air in quickly, but it's having to struggle to get it out.

So, IMO RR's are worth it!!! As for the pushrods, that is where the fun starts... You have to get your RR's then put some blue, black, whatever color on the valve stem and install the rocker with an adjustable pushrod. Get your preload set, and turn the motor over 2 full turns. Your wear pattern on the stem should be right in the middle of it. If it's off just a little, then you need to re-adjust the pushrod and do it all over again till you get it right. Once you get it right, then measure the pushrod and order that size.

[stantheman601]

I personally did it the per cylinder method. I tried the other ways but they jus never felt right to me. I had a friend help me out and we took turns rotating the engine. It may nt be the easiest way but it worked for me, and I felt confident that they were right.

[Tony]

I need to add an edit to my last post. I said with a cam you will net more, well duh lmao. With the right cam, you should push a crapload of power. But, just the RR's will net you more with that s/c than those of us with n/a motors. With a stock motor, the longer you can keep the valve open, and the bigger that you can open it, the better. I will bet that you can add 5-10% more HP increase with what you have over n/a.

[Blown1993Z28]

Originally Posted by Tony

You will know if you have them too tight or too loose. Too tight and you will hear the motor bog down. If you leave it like this, you will loose power and wear things out really fast. If you have them too loose then they make a crap load of noise lol.

Yes, Robs site is correct, you can adjust 8 valves at #1TDC and the other 8 valves at #6 TDC. I can spin my motor over with a 12" ratchet, so you shouldnt have any problem with a breaker bar.

As for the cost scaring you away, You need to think about something. RR's will net you about 15hp. The 1.6:1 over the 1.5:1 will net you a little more. BUT!!! You are running boost!!! With the right cam, you will gain even more than that cause you have air being forced into the motor. So, you can logiclly gain about 35hp just by putting on 1.6:1 RR's with 4.5lbs of boost. According to your sig, you don't have headers.... If you put some LT's on your car, you will gain more than that. Your getting the air in quickly, but it's having to struggle to get it out.

So, IMO RR's are worth it!!! As for the pushrods, that is where the fun starts... You have to get your RR's then put some blue, black, whatever color on the valve stem and install the rocker with an adjustable pushrod. Get your preload set, and turn the motor over 2 full turns. Your wear pattern on the stem should be right in the middle of it. If it's off just a little, then you need to re-adjust the pushrod and do it all over again till you get it right. Once you get it right, then measure the pushrod and order that size.

Thats exactly what I wanted to hear. The going rate for HP seems to be about $20 a HP. To me $400 for springs, pushrods, and RRs to net at least 20 HP makes it worth while. I can't really count the springs or pushrods because I will need them anyway when I rebuild my motor so its really closer to $10 a HP for the RRs. The pushrod measurement sounds involved but Hell, half of the fun is learning how.

P.S. I know I REALLY need some Pacesetter LTs. The only emissions legal ones are for 94 & 95 but the manufacturer said all I need to do is bend the EGR tube a little bit to fit the 93. I'm waiting until after I get my inspection sticker to mess with the exhaust (even though it should be emissions legal) Then I am replacing the entire exhaust (LTs, ORY or gutted cat, and Magnaflow CB) Not recently, but a few years back the Cops here in NYC were using a mirror on a stick to look at your catalytic converter. If you had an ORY they impounded your car and it costs a lot to get it back. I might actually just get a good high flow cat.

[Tony]

Well, you only have to do the adjustable pushrod on one valve (usually the #1 exhaust, it's the closest one to get to. All the others will be the same. You just have to remember this...

Stock rockers (stamped) are all about friction. There is a crap load of friction on the fulcrum as well as the tip. With a full RR, you will get rid of that friction and thus freeing up HP.

[Red Sleeper2]

Damn, I never thought bout over doing the valve adjustment and bogging down the motor. I went 3/4 turn and prob gonna go back and do just a half......

I have never herd of adjustable pushrods but they are prety self explanatory. To me pushrods are pushrods, I upgraded mine when I did my cam (see sig) just to freshin everything up. Not expensive and more insurance IMO.


This is a good thread... Learning a lot so far.

[Tony]

The adjustable push rod is only... ONLY to check length. So not start the car with it in there. But, it's the proper way to put RR's on or anytime you change something with the top of the motor.

[comhdw]

maybe i'm missing the obvious, but how do you messure 7.250? i've got mic's that go up to 7" (they will go to 7.400) calipers that go to 6", and what does it cost to have pushrods custom made? thanks

also, this has nothing to do with this thread but since i'm here, how do you upload pics to threads?

[95z28onjuice]

shoebox method of adjusting the valves is the easy way. when 1 is up do 8 when 6 is up do 8. as far as pre-load goes every builder will say something diffrent when it comes to this. but we have a method of doing it for diffrent set-ups that works great.

for race only 1/4 turn pre-load
street cars 1/4-1/2 depends on lifter age.

Blown if most of your rods were loose,and you have the stock rockers on the car, i would ook into whythere so loose if the car has less than 80k on it. the factory rockers are very hard to come loose,but yet you havea blower so this could be a reason.

Adjustable pushrods,like said before are for measureing what length rods you will need to run with you cam and head set-up. Note that in mose cases if the head stays on and the cam is under a .600 the lenghth needed on the car should be the factory length 7.200. but its always a good measure to have this tool when doing any valve train work because it can point out something that your eye might miss. like coil bind or the rocker not seated on the valve correctly. if the heads or gaskets on the heades are changed in anyway at all,you must check pushrod lenght

[Paulster2]

Originally Posted by comhdw

maybe i'm missing the obvious, but how do you messure 7.250? i've got mic's that go up to 7" (they will go to 7.400) calipers that go to 6", and what does it cost to have pushrods custom made? thanks

also, this has nothing to do with this thread but since i'm here, how do you upload pics to threads?

You purchase a push rod checker, which will range from 7-8" (I believe). Then when you get the length, most push rod manufactures (at least the good ones) make them to the length you need. You should be able to find what you are looking for on Jegs or Summit.

EDIT: They make them in all different sizes ... Check here.

[95z28onjuice]

Like paul and i have said you dont use a mic to measure pushrods.lol you use a pushrod lenght checker and it looks like a pushrod with a screw on it to adjust up and down.

As for picture, under additional there is a link box that says manage attachments, click on that and a box will pop up, next click browse and click the picture you want. i do 4 at a time with out any issues,sometimes more than 4 wont load and its a waste of 5mins.lol