Rocker arm PROBLEMS!!!

[vigman]

Andrew

A couple of things here.. ( and jumping in mid post)

1) Are the arms loose again? If so I would remove one rocker arm and look at the stud.

The studs are pressed in, so as the heads heat up the metal expands and so should the stud to keep the press..but SOMETIMES the damn things just get pulled up!

Look at the base of the stud.. you will see a line of oil staining from where the old stud sat in.

From the base of the stud boss ( casting )
1/2 inch+/-1/32 to the base of the threads on the stud to 1 3/8 to the tip of the stud.
327 head 461 casting..but should be same.

Now I do not want you to panic...however if the pushrods are NOT bent and the springs are NOT binding AND you did not put a WILD cam in there( and the clincher ) the studs do not show ANY signs of pulling up.

You need to inspect the base of the lifters and check the cam lobe for lift.

If your ground the cam FLAT ( lack of oil, improper break in ) that is another remote possibility.... you DO need to check this.

If the studs are pulling out!
3 ways to resolve this.

Stock heads removed from car

1) Drill in the heads for threaded studs.. DO NOT ATTEMPT DO DO THIS ON THE CAR.. you have to fly cut to get the proper relief for the COOL new studs with guide plates ( See my post Mystery 327 next gen) in the C-3 section. They also make straight studs where you pull the old ones out and just tap & thread the new ones in... but you have to use some NASTY thread lock to keep em there ( not to mention the water jacket that runs RIGHT UNDER the stud bosses)

If you only one or 2 offenders.

2) Pin the existing studs. You hammer down the old stud back into position and cross drill at the base of the casting.. and press in a cold roll pin. USE SAFETY WIRE when the repair is complete!

3) New heads.

Vig!

 

[vette-dude]

Following this thread and had one other thought. Your cam lobes may have gone flat. If this was a used cam ( or sometimes even a new one will do it) and new lifters you may have flatten the lobes on the cam. Does it backfire through carb or have a popping noise through carb/injection? I have this happen more than once to cams not hardened correctly and old cams with new lifters installed. Hope this isn't it but it does sound familiar. Did it happen within the first 2 hours after you got it driveable? Good luck

Randy

 

[andrewmckernon]

YOU HIT IT ON THE MONEY

Well, now that you metion it, when i first gor it running, it was very responsive, and then as the drive down the highway lengthened, response came very sluggishly. It did start popping and backfiring quit a bit when i reved it up. Is this because of flattened lobes on my cam? What would be the best avenue to fix it? and what type of cam should i replace it with, aftermarket or stock??

-andrew

 

[vigman]

Andrew

I need more history on the car...

And a description of what happened in what order.



Vig!

 

[andrewmckernon]

Rocker Arm Problem History

When i got the vette a few months ago, the distributor had been shifted 90 degrees to compensate for a reach problem in the tach cable. After running the engine a few times with little success, i discovered this and reconnected the spark plug cables in the correct order. The engine ran fine for quite a while.

After nearly 500 miles, I heard a harsh clicking noise under the hood, and took off the valve cover to investigate. A rocker arm was busted right in half, and that explained the recent backfiring, as the rocker arm that broke was an intake valve and there was always left over gas in the valve when i started it. I bought a new one, and put it on, tightened it, and went of with me business. The engine was still clicking, and so i took off the cover again and adjusted the rocker when it was hot. NO HELP.

The rocker arms have been coming loose ever since. I don't know if it's an upper engine problem or a lower. Could it be my cam, or are my studs on the head backing out causing the rocker arms to loosen? Any help?

-Andrew

 

[andrewmckernon]

NOT THREADEd

actually, i dont know. do the studs come push in stock? If so, i guess they wouldn't be threaded now would they....


-andrew

 

[vigman]

The stock ones are PRESSED IN

Not threaded!!!!!

IF you cracked a rocker.. 1 of 2 things

1) REALLY HOT & lack of oil

2) Somebody has been racing this engine.


You need to check the following before we can proceed.

Lift of the cam... roughly 1/2 of an inch at the rocker side ( on valve ).

Do you have the stock intake?

WHY was the distrib tweeked?

Is the cam stock?

Is the valvetrain stock?

Are the studs backing out of the head?

Are you keeping the engine UNDER 5 grand ( RPM )

Vig!

 

[andrewmckernon]

Vig: The scoop

THe distr. cap was rotated 90 degress to accomodate a short tach cable, which didnt affect the timing any. Everything is stock. From the intake to the cam. The studs are not backing out, primarily noted by looking for an oil line. And yes the engine has been kept under 5000 rpm. It's very taxing this rocker arm problem...

-andrew

 

[vette-dude]

I still think you have a bad cam. Was the cam replaced? If so, were new lifters installed and was the cam a new one ( not used)? Then was it broke in properly? If all your rockers arms are getting loose, then I think this is the problem. You might want to pull your oil filter and cut it in half. Check the pleats for shiny bits of metal ( use a magnet) and if it is excessive this will indicate something has gone south. If you continue to run the car ( if it will run at all) in this condition, you will soon be replacing the bearings. To fix, replace cam and lifters. You will have to flush the oil passages in the block after you remove the cam. (Not an easy thing to do.) If you are not mechanical, find a shop that knows what they are doing. Any debris left from the bad cam will go directly into the oiling system and will cause further damage. The filter will help get rid of some of it but plan on changing the oil after break in of the new cam. That's my $.02.

Randy

 

[Mako]

Re: Vig: The scoop

The distr. cap was rotated 90 degress to accomodate a short tach cable, which didnt affect the timing any. Everything is stock. From the intake to the cam. The studs are not backing out, primarily noted by looking for an oil line. And yes the engine has been kept under 5000 rpm. It's very taxing this rocker arm problem...

-andrew

If you can afford to install roller rockers with poly locks, that will solve the problem permanently plus you can get a little more power out of the engine too.

I'd also inspect that one push rod, as it's likely bent.

Pull the rod and roll it on a piece of window or picture frame glass like you were inspecting a pool cue on a pool table. If it's warped, it'll be pretty obvious. Also look for scuff marks on the pushrod where it may be rubbing up against the head.

If the rod is bent, that may be part of the problem. You can also inspect the threads on the rocker arm stud - are they messed up? You may need to run a re-forming die down that one stud to freshen up the threads.

To inspect the cam lobe you either pull the intake or bum a degree wheel and dial indicator with a magnetic base and flex mounting and measure the lobe lift and compare it to others.

My understanding is the main problem is the rocker nut won't stay put. If that's wrong, let me know...

Thanks!
Allen

 

[andrewmckernon]

Poly Rocker Arms

How much do poly rocker arms cost, and typically how much hp do they add? Also, if i can't afford roller rocker arms, i wash thinking about investing in some nice new push rods, what type do you recommend, and how much would those cost. I've heard mixed things... can you help??

-andrew

 

[Rowdy1]

Re: Rocker Arm Problem History

When i got the vette a few months ago, the distributor had been shifted 90 degrees to compensate for a reach problem in the tach cable. After running the engine a few times with little success, i discovered this and reconnected the spark plug cables in the correct order. The engine ran fine for quite a while.

After nearly 500 miles, I heard a harsh clicking noise under the hood, and took off the valve cover to investigate. A rocker arm was busted right in half, and that explained the recent backfiring, as the rocker arm that broke was an intake valve and there was always left over gas in the valve when i started it. I bought a new one, and put it on, tightened it, and went of with me business. The engine was still clicking, and so i took off the cover again and adjusted the rocker when it was hot. NO HELP.

The rocker arms have been coming loose ever since. I don't know if it's an upper engine problem or a lower. Could it be my cam, or are my studs on the head backing out causing the rocker arms to loosen? Any help?

I'm thinking something was way wrong with the timing AFTER the moving of the distributor, wires etc. Moving the distributor 90 degrees, not marking #1, was the engine retimed after?

A decent set of roller rockers are about $150.00 and up, they claim as much as 10 to 15 HP, depends on who you listen to. I'd be checking everything out before I went that route, something sounds "fishy" as in overlooked.

-Andrew

 

[vigman]

Andrew

Here the way I would approach it!

1) Remove the oil filter and cut it open look for bit's of metal as suggested. If the cam went.. there going to be LOTS of metal in the filter.

2)Remove plugs, remove valve covers ( there should be a fair amount of oil in the top of the head)
.. do the adjustment procedure as noted ( in one of my earlier posts) but DO NOT ADJUST anything.. just move the valves to their proper order and see if they ALL are loose or certian ones are loose.

3) Check the pushrods as described. Do one at a time.. and put it back when you are done

4)Check for wear on the bottom of the rocker arm.

5) Are the nuts for the rockers factory? Or some after market thing.

6) Are the threads at the top of the stud cool?
Let me know

Vig!

 

[vigman]

Oh ah HAH

You DID get new nuts with the rockers..

So what kind of rockers do you currently have?

What do the nuts look like.. standard or trick?

Are they 1.6 to 1 rockers?

We need to know~

Vig!

 

[68Roadster]

Vig,
Do you think the original problem here with the distributor and the spark plug wires has contributed to this....I'm just trying to analyze the problem Andrew is having and it all begins after he swapped around the wires.

Would going back and checking the dist. at TDC and making sure the wires are on the cap in the correct firing order be prudent?? I know he said he drove 500 miles before anything happened but it doesn't make sense. Could he have jumped time?? (not in the Austin Powers way) Doesn't this bend valves? How can he check for that??

Andrew - when you got the car, was it running OK?? How long since the motor has been gone thru?? Do you need some help?? I'm an aircraft/powerplant mechanic by trade but with Vig guiding ya, should be able to figure this one out......

Cee

 

[vigman]

Well I dunno, I doubt it

The problem is simple, as long as the lifter was DOWN when the adjustment was made there shouldn't be a problem.

If he fired up with all the lifters totally mis adjusted he would be spitting out spare parts and rattling like Carmen Miranda maracas.

I would bet that he didnt crank down the extra 1/2 to 1 turn AFTER finding ZERO LASH

And as the engine heats up ( oil gets thinner) the valve opening got smaller cause the lifters wouldn't pump up all the way.

But again a wild guess at this point..


The distrib position.. really is just a pointer and if the wires on the cap were out of FACTORY order.. and then moved to the correct firing order it's no big deal.

The problem started when he changed rocker(s) and ALL the rockers are loose..
is what I'm reading here.

" The engine ran fine for quite a while."

"A rocker arm was busted right in half"

"as the rocker arm that broke was an intake valve "

" I bought a new one(SINGULAR), and put it on, tightened it, and went of with me business. The engine was still clicking, and so i took off the cover again and adjusted the rocker when it was hot. NO HELP."

"The rocker arms ( PLURAL) have been coming loose ever since."

"I thought I had adjusted my rocker arms correctly. I thought I had found absolute zero"

So new questions
1) Did you just buy the ONE rocker or a whole set?

2) Did you adjust 1 rocker.. or ALL OF THEM!

3) The absolute ZERO comment.... you found the point of "O" play.. then how far did you tighten the rocker?

I find this confusing.. Andrew we need to start from square #1 and adjust the valves correctly...then measure the lift.. to see if the cam flattened out, or valves were kissing pistons etc.etc


Vig!

 

[Jack]

Re: Poly Rocker Arms

How much do poly rocker arms cost, and typically how much hp do they add? Also, if i can't afford roller rocker arms, i wash thinking about investing in some nice new push rods, what type do you recommend, and how much would those cost. I've heard mixed things... can you help??

-andrew

Speed-Pro/Federal Mogul pushrod set pn RPK5000R ... under $25/set of 16 ... hardened, can be used with guide plates, stock length ... very good quality pushrods. Available at local parts stores or mail order.
JACK:gap

 

[andrewmckernon]

From Square one Vig...

The distributor cap was turned 90 degrees. The top dead center of valve one was marked with a groove in the top of the cap, and i've been working off that ever since.

I then bought one singular rocker arm when i discovered it broken. I replaced it and it's nut and washer and started it up. After about ten minutes of running the engine, it was loose again, as well as numerous others. The left side of the engine was the only side causing problems. I didn't bother to change the right side rockers, but did change all eight on the other side. Can this cause problems? I checked for wear on rocker arms and nothing seemed to be the problem.

I have since tightened the rocker arms in order of TDC and started the engine. The clicking is still there, and I can only presume it is a rocker arm coming loose again....

Everything is stock mind you. I have not yet taken off the oil filter to see if the cam has shreaded. How would i cut through the filter? Is it a lot simpler than i expect?

Hope we can figure this out...

68Roadster, I'd like some help. That'd be great. Tell me when a good time is, when the weather gets a little dryer and a little warmer...

-andrew

 

[vigman]

Re posted for clarity!

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!

 

[vigman]

And your post

NOT SHOUTING..JUST USING CAPS FOR CLARITY!

"The distributor cap was turned 90 degrees. The top dead center of valve one was marked with a groove in the top of the cap, and i've been working off that ever since."

BZZTTTT WRONGO... it's the CRANK & Cam you need to be concerned with.. the distrib is OK IF it is UN disturbed... but I always use the crank/cam position, AND WHO MADE THE MARK???? THE FACTORY DOESN'T!

"I then bought one singular rocker arm when i discovered it broken. I replaced it and it's nut and washer and started it up."

Was the valve being pushed down while you removed things?... and as you were tightening the new one into position.. did you check the position of the cam by rotating the engine?

NOTE HERE.. TAKE THE PLUGS OUT WHILE YOUR TWISTING THE CRANK.. IT WILL TAKE THE STRAIN OFF THE CENTER BOLT ON THE HARMONIC BALANCER AS YOUR TWISTING. #1 NEWBIE MISTAKE,, I SNAPPED THE BOLT OFF THE CRANK!!!!!

After about ten minutes of running the engine, it was loose again, as well as numerous others.

AND YOU TWISTED NO OTHER ROCKER ADJUSTMENTS...RIGHT?

The left side of the engine was the only side causing problems. I didn't bother to change the right side rockers, but did change all eight on the other side.

AH HAH... SO YOU DID..I'LL BET YOU JUST MIS ADJUSTED THEM... START BACK TO SQUARE#1

Can this cause problems? I checked for wear on rocker arms and nothing seemed to be the problem.

WELL YEAH.. I'LL BET YOU WERE RUNNING ON 4 CYLINDERS!

I have since tightened the rocker arms in order of TDC and started the engine. The clicking is still there, and I can only presume it is a rocker arm coming loose again....

AGAIN... BACK TO SQUARE 1.. AND ONCE YOU DO GET EVERYTHING SET..YOU HAVE TO MEASURE THE LIFT OF EACH ROCKER

Everything is stock mind you. I have not yet taken off the oil filter to see if the cam has shreaded. How would i cut through the filter? Is it a lot simpler than i expect?

HACKSAW...PIPE CUTTER...DIE GRINDER..TINSNIPS DOESN'T HAVE TO BE PRETTY..JUST GET IN THERE!

AND ANSWER THE FOLLOWING
WHAT RATIO ROCKERS DID YOU GET? STOCK? WJERE DID YOU BUY THEM FROM?

Vig!