Rocker arm adjustment question/help needed...

[rrubel]

After replacing my rocker arms last fall (with roller-tips), I've come to realize I didn't tighten the valves properly (mostly by the sound/feel of the engine). So today I went to try and adjust them again.

So as I'm working my way around the firing order, I've got a chart I'm following from last time (starts out TDC: 8 exhaust, goes around past TDC: 5 exhaust, etc). Maybe I'm mis-remembering, but I thought I could adjust both valves that say to be adjusted at TDC (ie, 8 and 5 exhausts). However, though 8 stays fine, as I keep adjusting other valves #5 gets WAY loose again. Then another one does the same thing. As I look at them, I realize that TIGHT on some arms is nowhere near as tight as on other arms (the nut isn't screwed down anywhere near as much). The pushrods for almost half the valves I'm adjusting are UP, keeping the arms from seating as far down as they should be. Am I adjusting in the wrong order? Is my distributor rotor on 180 degrees off (It's the one that was on when I got the car)? Should I only adjust ONE valve per 45 degrees, rather than TWO?

I do know I have the shafts lined up right - I took a plastic bowl, cut off the rim, and made a template using the spark plug terminals on the distributor cap so I could make sure the rotor is lined up with each terminal properly (and when I came back around to the #1 wire, the TDC mark was about 2 degrees off, which is pretty close I think).

Any help is appreciated...
Thanks!
[RICHR]

 

[vigman]

Ya know I got dinged on this too!( rocker adjustment )

The one thing ya gots to remember.. is 4 rotations of the crank=1 rotation of the cam

So ya can get goofed up in the Correct initial line up of the cam. So lets review.

Firing order
1-8-4-3-6-5-7-2

( Stolen from GM book of wisdom )

Assuming a non running static adjustment

Adjust valves when lifter is on base circle of camshaft lobe ( the backside of the lobe ) as follows. And in a perfect world when your at #1 firing position on the crank.. and the cam's in the correct position.. the distrib's rotor will be pointing@ the #1 hole.


Crank engine to #1TDC firing position
( Piston UP both valves closed)..but if the valves for (#1 )are CLOSING as your coming up on the timing tab for TDC, you actually are in the #6 firing sequence. Rotate the crank 1 more turn.


So when your there #1 TDC
Exhaust 1-3-4-8
Intake 1-2-5-7

Now rotate ONE revolution and back to the TDC mark
Exhaust 2-5-6-7
Intake 3-4-6-8

As you adjust... you loosen the nut so you have just a pinch of play ( you dont feel the spring of the hydraulic lifter starting to load the pushrod ) take out the free play, and the BOOK states tighten 1 turn. some people say 3/4... other people state 1/2

So the threads are FINE and I believe 3/8 24 ( or 24 threads per inch ) so for a full rotation of the nut.. you've seated the push rod into ther lifter 1/24th of an inch... if you go half as much youve seated it 1/48 of an inch... So not a big deal here ( I go 3/4 of an inch)

My .02


Vig!

 

[rrubel]

Gah. I'm still confused...

"Crank engine to #1TDC firing position
( Piston UP both valves closed)..but if the valves for (#1 )are CLOSING as your coming up on the timing tab for TDC, you actually are in the #6 firing sequence. Rotate the crank 1 more turn."

Should this be TWO more turns? If I rotate one more turn, then the distributor would be facing the back rather than #1 cyl, right? Or not?

At #1 TDC, cyl 1's valves must both be CLOSED? Makes sense since it's firing.

Ok... back I go once more into the breech. Or under the hood.

Oh, this may be a no-brainer but is it safe to manually crank the engine backwards? Ie, if I missed the timing mark and need to come back to TDC?

Thanks much for the explanation. I'll get it yet!
[RICHR]

 

[evolution]

Geeze, I just went in order. Start at #1 TDC and hit both int/exh and go TDC around the firing order. Worked for me with a 1/4 turn after pushrod spin play was nixed.

 

[vigman]

Clarity

"Crank engine to #1TDC firing position
( Piston UP both valves closed)..but if the valves for (#1 )are CLOSING as your coming up on the timing tab for TDC, you actually are in the #6 firing sequence. Rotate the crank 1 more turn."

So as your coming up to #1 TDC.... the valves should be static during the final portion of the move ( say the last 30 degrees of motion while your coming up to TDC).. as opposed to JUST closing as you making the move.


Vig!

 

[rrubel]

Ok, I think I got it... your method is the "batch" method that others have mentioned, right? It seemed easier and when I was done I manually did a couple of rotations of the crank and everything seemed tight (very slight amount of play in the pushrods sometimes - I could barely turn using both hands the ones that were adjusted at that particular TDC). Put it back together, started it, sounds MUCH better than before. I have some clicking, but I still think it's injectors - any easy way to tell the difference? These have always been noisy, and got a wee bit louder when I raised the fuel pressure.

Thanks again for your help.
[RICHR]

 

[vigman]

Ticking= injectors

You can use the following..

As the engines running ... get a mechanics steath o scope put it on the injector.. and unplug the injector as you are running to hear the diff.


Vig!

 

[JAKEJR]

Guy, guys, please. No complicated adjustment procedures are needed to do this job. Do it the way the Pros do it.

Ever go to a NHRA meet and watch the big boys adjust valve lash between rounds? Not a single guy resorts to that convoluted adjustment procedure found in the GM/Chilton manuals. Why? It's ssoooooooooooooo complicated and sooooooooooooo prone to error. Not to mention that when running some aftermarket cams, it plain won't work.

Even though when using a hydraulic cam we don't set "lash" but lifter preload instead, the procedure is the same.

You start at the front of the engine and work toward the back, one valve at a time, EIIEEIIE, simple, and there's little chance of misadjusting the wrong one.

The procedure; bump the engine and watch the #1 INTAKE. When the rocker goes past full lift and about 2/3rds or so toward closing; STOP Now adjust the #1 EXHAUST.

Now bump some more, this time watching the #1 EXHAUST. As soon as that rocker begins to open that valve, STOP. Now adjust #1 INTAKE.

Keep on going right down the line, one after the other. SIMPLE.

Yep, the tried and true method is to watch one to set the other.

I think you'll find that virtually all engine builders do it that way too. I've used it for more than 30 years with complete success.

Hope this helps. Jake

 

[vigman]

Well Jake thats another way to do it

But I think infering that GM are NOT pro's is somewhat misleading.

I ( personally ) like to quote information that is accurate.. and since I do not know the expertise of individual members.. I try to give the most fool proof advise possible, from the GM shop manuals.. then attempt to translate to more digestible terms.

Your procedure IS 100% correct.. but for a novice.. it MIGHT be mis understood.

The point of your procedure is while one lobe is UP the other has to be closed. ( but your doing a LOT more twisting of the crank to keep moving the cam into the correct position)

This also ASSUMES that all the rockers have some form of tension on em.

Now I do not disagree with your procedure.. but it does assume some mechanical knowledge.

"Ever go to a NHRA meet and watch the big boys adjust valve lash between rounds?"

Some of our members want to work on their cars to save money or garner expertise....but are green around the gills.



Just my .02


Vig!

 

[Tom Bryant]

I agree with Jakes method as you eliminate the possibilty of the heel of a lifter still being on the lower part of the lobe ramp on longer duration cams. I have also had success every time using Vigs method on stock replacement hydraulic cams.

I would not use the so called batch method on a solid lifter cam as you are dealing in thousands of an inch adjustments. On hydraulic cams you are preloading the lifter plunger somewhere in the center of it's travel and it isn't so criticle. An old rodders trick, said to afford more rpms, has been to tighten the rocker 1/4 turn after clearance is eliminated. I don't know if it actually works but we always thought it did.

Irreguardless of which method you use the idea is to have the lifter on the base circle of the cam before adjustment is made. Loosen the rocker nut until you can spin the pushrod freely between the thumb and forefinger. While moving the pushrod with your fingers tighten the rocker nut until you feel the clearance go away. The pushrod will stop moving easily. Then tighten the nut 1 turn to center the plunger in the lifter.

As long as you have each lifter in the proper position when adjustment is made no further adjustment will be necessary.

Tom

 

[rrubel]

One of the problems I have with the "old hot rodder's method" is that it requires a lot of eyeballing - where exactly is 2/3 towards closing? I find it hard enough to see when a valve is open or closed completely (well, ok, I can see full open or full closed - but somewhere in the middle?).

Vig's batch method seems easiest for the simple reason that TDC is TDC - line the mark up and as long as you're on #1 and not #6 then you KNOW everything is ready to be set. Moving 45 degrees and doing two at a time just imho increases the chance for error.

I think the true answer, though, is for me to get real full-roller arms that can be more easily adjusted while the engine is running (I have wrench clearance problems with this setup which is why I have to do static adjusting).

So - as long as I don't get overly loud clicking then I should be OK, right? Power delivery is much smoother (before the adjustment, there'd be an RPM after which power came on stronger - almost like VTEC) but it almost feels weaker to the butt dyno. I may also be smoking tires more since it's quite cold out, which would reduce acceleration...
[RICHR]

 

[vigman]

Actually the full rollers are almost IMPOSSIBLE to do running

With the CRANE locks .. you have an allen set screw on the top of the nut to lock the nut down to the rocker stud.. ( looks like an inverted top hat) and where the brim of the hat would be there's your flats for the nut.

So you now have 2 tools to deal with while the engine is running...


Do the procedure ( which ever one you choose ) and you will be good to go!


Vig!

 

[JAKEJR]

Actually, as with most things, there is more one way to do it. It's really boils down to one way being easier or more familar than the others, to the user.

Over the 30 or more years I've been screwing on these suckas, I've tried all the methods mentioned in this thread. Even the engine running procedure with oil deflecting clips. One guy even recommended putting a dial indicator on each retainer - think about what a nightmare that would be!

As I said, though, there's more than one way to skin a cat. So choose your weapon and have at it, I say.

GM's Shop manual - the phone book sized one that I bought for my 86, has lots and lots of proceudres which most guys who work on these engines on a regular basis have found to be too time consuming and, in some cases, unnecessary. Work-arounds have been found for many of the procedures and in a lot of cases the results are better using them.

Why does GM recommend such complicated procedures? Who knows; may be warranty concerns, come-backs or upping the $ rate for GM mechanics doing the work, whatever.

In any event, if the JEG's, etc. felt it was the way to do it, you can be sure they wouldn't have jeapordized their Pro Stock Championship quest by deviating from the GM recommended way.

Here's another one: Where in the GM Service manual does it give the procedure to degree in a camshaft? I haven't found it. I only find the "line up the dots" tip. So when that topic comes up, opinions vary across the board as well.

Some say, "Naw, not needed", others say, : "Well, only if your cam exceeds (fill in the blank) specs", others - like me - degree in everyone no matter what. Then we have the varying opinions of which degreeing procedure to use - Lobe Centerline method, degree @ .050, straight edge across the lifters, etc. Fooling around with these big hunks of metal is as much an art as a science.


Another point to remember, too, is that when adjusting preload on an aggressive aftermarket cam, one that has fast ramps or a reduced base circle, the GM method doesn't give consistent results.

As another pointed out, the crucial factor is ensuring the lifter is on the base circle of the lobe and that the preload amount is pretty forgiving. I've run everything from 1/4 turn to as far as 1-1/4 turns of preload.

And, no, 2/3rd closed isn't critical on most camshafts - those that are streetable. All you've got to do is estimate it; not rocket science here. If you study the valve cycles, you'll see that. It's not spinning the pushrod between your thumb and index finger until you feel "slight" resistance.

As you move up to longer duration cams though, your cam will have more over-lap, meaning both intake and exhaust valves will be open at the same time, so getting 2/3rd to 3/4ths or so becomes more important.

To me, if someone is a first-timer, using GM's recommended procedure is probably the most complicated and prone to error method to choose. Moving from one side of the engine to the other while at the same time being sure to select the correct rocker is way more complicated that just going down the line.

One more tip: if the engine has been run before, back off on each adjusting nut/poly lock completely for a minute or so to allow the plunger to fully rise to it's highest position in the lifter. Then slowly begin tightening the nut/lock and use the up and down method to determine when all the slack is taken up. At that point, establish your preload.

But to each his own I say.

If you want to read about a real horror story, let me tell you about this over $23,000.00 434 SB I've been building for ALMOST THREE YEARS NOW! Talk about problems!!!!!!!!!!!

Jake

 

[Bob Yates]

I'm not saying I'm right but I was a Chevy GM tech and I always adjusted mine while running... when the slap goes away turn a full turn down. On a lot of the small blocks the cam bore is not centered . This is why I did what I did . Is it right or wrong I can only say all of my engines run good for me.I all so did my roller rockers this way and they did fine. It's best to do what you understand........Bob

 

[vigman]

I agree with Bob's statement

" It's best to do what you understand"

Trying a new procedure if you DO NOT understand it can be a mess ( but work ) and at worst ruin your engine!

The adjustment procedure while running is a tried & true method.

The adjustment I gave is the way GM does it @ the factoy.


Both work

You choose.

Vig!

 

[rrubel]

Well, I wound up following the batch method and it seemed the easiest of any. I'd love to do the running one, but as I said there isn't enough clearance within the arms to put the sockets in. I've only driven the car once (rain/snow around here) since I did the work, but it sounds OK.
[RICHR]

 

[vigman]

Not to do the Nayh-Nayh dance

( or anything like that)

I THINK you chose wisely



Vig!:booty

 

[Bob Yates]

Hey ... glad you found something that worked for you. That's a good feeling...keep vett'in......Bob

 

[Tom Bryant]

You will be able to test it out in no time. Spring is coming. I know because I've seen the first signs already. Michigan has put out a couple hundred construction barrels at I-69 and I-94, and the Meier Store has the lawn furniture and spring cloths out.:cool

Also saw a NASCAR transporter heading south on I-69 a few days ago.

Tom

 

[rrubel]

Ah, but 'Punk' Phil has seen his shadow...

My goal is to have everything running right by the Caravan in June, but I have a lot of other projects to complete before then (10th anniversary is coming up - LOTS of plans).

Need to find a new liner for my solid roof now.

[RICHR]