Question : Tightning rockerarms on 3600 3.1 '95 Lumina APV

[Texasguy]

Hello,

I am doing a valve job for the very first time in my life. My car is '95 Limina APV (van) with 3600 3.1L, 135K miles on it. I am not a mechanic but very handy.

I do a valve job because I had some bad knocking sound (and maybe some missing), all of the sudden, that seemed to rock the rear valve cover. A mechanic said that I might have some loose parts or bad lifters.

Lifters were indeed messed up, those that looked good were not springing any more, just totally stuck. Others were with top cover of the lifter flipped open and rods inside of the lifters inners. I was surprised the engine was running totally well before the sudden knocking developed. Rocker arms, in general were very loose, you could remove rods for some with bare hands (probably due to bad lifters).

I have changed everything that can be replaced with new parts, whatever the "valve job" exposes you to change. Seats, springs, lifters, rods, you name it. Everything is after-market but a correct size and all.

Finally, I am at the glorious finishing and assembly stage. Done a rope method to change the springs, it was a grand undertaking.

I have ran into a problem.

I have Chiltons manual and GM manual for my car. Chilton's says to tighten rockerarm 3/4 turn after the lash, GM manual says 1.5 turns... twice as much. I did 1 turn for now.

My problem that after I tighten proper exhaust and intake with cylinder #1 at tdc, then proper ones with cylinder #4 at tdc.. (with 1 turn after the lash) Everything seems to be ok. Then I crank the engine with the starter for a few turns, I look at the rocker arms. Some are a little loose, I can move them side to side just a little. However, even if I did 1.5 turns after the lash, I don't think I would cure it.

Is it OK for rocker arms to be a little loose at some random position of the engine? Or my tightening sucks?

I also think that lifters might get saturated with oil and make rods more stiff. I did give my lifters a bath in oil before the installation, probably by now most oil might have left the lifters while I was playing with the tightening.

I am pretty much ready to put the covers on but I am not looking to disassemble the whole thing again. It is a van and it has 100's of parts and connections on top of the engine. It would be dreadful to go back and correct something.

[95Grand-Am]

Side to side motion is not important a little is nornal. It sounds like your doing it right except you need to have the intake gaskets on first.

[tractorman]

Tex- I don't know if you're looking at the wrong manuals or what... but the tightening procedure that you're describing for the rocker arms sounds like the procedure for a small-block chevy V8 engine. Maybe some of the older 60-degree v6 engines use that procedure... but not yours. On your engine, the rockers are not adjustable- you simply tighten them down to spec. (don't remember exactly what the spec is. Somebody please correct me if I'm wrong, but I'm thinking it's about 22 ft-lbs.) Regardless, there is no 'adjustment', no tightening of 3/4 turn or 1 1/2 turn or anything like that: You just tighten down the pedestal and that's it.

But before you do that, I have to ask: Did you keep the pushrods in order? If so, then great... you're good to go. If not, then you'd better not tighten down the rockers or crank the engine until you're SURE that the pushrods are all back in the correct spot. The intake and exhaust pushrods are different lengths; if you get one swapped, valves will hit pistons... and you'll be pulling a head or two.

Good luck and Gawdspeed.

[WrathOfSocrus]

The Lumina APV came with an ironhead engine. One look at the pics supplied shows this . . . the tightening procedure is correct.

[geoffinbc]

Agreed. He has iron heads so preload needs to be set. 1 turn after zero lash is enough preload. One way to visually verify you have tightened all the rockers the same is to measure the exposed threads on the stud and verify they are all the same height. If you missed one you will quickly notice it.

[Texasguy]

Can someone make a clear description of when I reach zero lash? Seems like that there is no clear line between before the zero lash and after.. Could someone give me a tip?

Also, do I have to make sure that the lifters are saturated with oil before I do tightening? As I said, lifters act differently if they got oil in them, I am not sure if zero lash should be done on dry or fully lubed lifters.

[tractorman]

My bad. I assumed that all 1995 3100 engines were the same. Clearly that is not the case.

Tex- zero lash is all about feel... it's gonna be hard to get the right technique across via keyboard. But basically you tighten the adjusting nut while GENTLY wiggling the rocker arm. That way you can feel when you've taken the lash out. That's how I do it anyway... some people turn the pushrods- I don't care for that method myself, but everybody has a different 'feel'. The goal when going to "zero lash" is to tighten down the valve train until the parts just touch; no free-play at all, but also not collapsing the lifter at all. Anyway, once you get them to zero lash (at TDC compression stroke), then go another 3/4 to 1 1/2 turn (depending on who you ask. If in doubt, I don't see anything wrong with splitting the difference at 1 full turn).

A lot of people soak the lifters in oil before installation. It's probably a good idea, though not strictly necessary. You DO need to lube the bore and the outside of the lifter with some clean oil so it'll move nicely in the bore (this is particularly important on flat-tappet engines, so that the cam & lifters can break in properly). As far as the lifters acting differently with oil in them vs. without- yes, they will be harder to compress when they have oil in them. But when you're getting the rockers to zero lash, you should NOT be compressing the lifter at all. You will only compress the lifter with that additional 3/4 to 1 1/2 turn (depending on who you ask, apparently).

Now, this may be obvious to you... and I don't mean to condescend. But I've SEEN people overlook this step- so bear with me: You have to put each cylinder at TDC compresson (so that both valves are fully closed) and adjust each cylinder separately, turning the engine to the next cylinder each time. You can't just adjust the rockers without turning the engine over.

Here's a tip so that you'll KNOW that you've adjusted all the rockers: Go buy a little bottle of white-out. When you adjust each rocker, mark the adjusting nut with the white-out. That way you can't miss one. I do this all the time on diesel engines.

Keep in mind that these are just general instructions for this style of valvetrain. I've never worked on the older-style 3.1 engine, just hundreds of 'other' engines (including some of the newer 3100's). So somebody please correct me if I'm wrong. You know... like last time.

[SappySE107]

He doesn't have a 3100. It is a TBI iron head 3.1. I don't know what a 3600 is though but maybe it has something to do with minivans.

Zero lash is the point that the pushrod is just starting to press down on the plunger inside the lifter. The ideal spot for pre-load is to bleed the lifter down so there is no oil and the plunger is fully compressed. Count the turns from just starting to press on the plunger, to fully compressed and then back off half way. You don't have to be exact, hence the range you are seeing in the books.

DO NOT SOAK THE LIFTERS! You want them to be empty so that they can pump up with oil through normal operation and will not be solid on initial start up.

[Texasguy]

Thank you all. I guess I have to go lighter on tightening than I was doing. That is a very important step and I must do it right. I am doing this van after coming from work and in Texas heat I lose pounds by sweating them out. Darn, it just takes so much time.

BTW, the "3600" was a misguided typo.

May I ask another question, installing gasket on the intake manifold. I have the gasket, the special spray, and a special paste (aka liquid gasket).

How much should I soak the gasket with that spray? Any tips on what order of spraying and laying the gasket I should follow? The manuals seem to be a little on the dry side when it talks about proper gasket application. I am aware that the bolts should be tightened with a torque wrench in a special order.

How long should it dry before crossing the fingers and cracking the engine? Since I didn't change the camshaft but did change the lifters, should I let the engine race for 20 mins or not?

What do I do with the extra parts that might be left over?

[geoffinbc]

I never put anything on the gaskets. If there is abit of corrosion around the water passages then use a little RTV Silicone around that area. Torque the manifold in several passes and obviously you need to use a torque wrench.

You will need to break in the cam again with the new lifters so follow the standard break in procedure and use a break in additive.

[Texasguy]

Do I need to use any thread-lockers for the bolts to put the intake manifold back?

Do I need to use the 'silicone gasket cream' for the bolts as well?

[geoffinbc]

No you don't have to use anything special for the iron head engines. I just used a little lube on the threads.