HOLE IN ROCKER ARM COVER

[56pan]

Hi Guys. I put about 50 miles on my newly rebuilt engine. Then I noticed a small dimple in my rear rocker arm cover, exhaust side (from the inside). After a short while the chrome started to chip off. Then, a crack appeared and oil was seeping out. The '56 was running good but I knew something was wrong. I pulled the head off and removed the cover. I found the rocker arm is hitting the cover. Just slightly. What doI do about this? I never had this problem before. I have the cork valve cover gaskets. Maybe use thicker gasket?? I have solid lifters and pushrods and aftermarket covers. Thanks. Bill

[Cotten]

Bill!

Your problem is not unusual at all.

How high of a lift is your cam?

Since your aftermarket tin is already blemished, the eventual wave in the flange that extra fat and spongy gaskets can form probably won't bother you (until they leak), but a more effective measure may be to merely grind upon the weld button that is hitting the cover.

Although very early models used a 'welch plug', later models sealed a drilled gallery in the arm with filler rod. Dress it slowly to avoid opening it up, of course. A dab of silver solder will fix it if you do.

I have a set where the filler rod was inserted into the gallery so far that they actually block the feed to the pushrod! Yet no harm resulted; The design is one of the toughest in automotive history, and a cornerstone of the Pan's legendary durability.

....Cotten

[56pan]

Thanks for the reply Cotten. I don't know exactly the lift on my cam but my engine builder told me it was a little more than stock. I had this engine rebuilt about 8 years ago and it's been sitting since or I would take it back to him. Warranty long gone. So, I'll do this myself. Good idea to grind a little bit of material away. I don't think it will be much. How will I know when I have removed enough? And you think I should stay with the (thin) cork valve cover gaskets? Any suggestions for head gaskets? Thanks a lot.
Bill

[Cotten]

Bill!

I would not judge your builder harshly, as I assure you it can happen to the best of us!
A return to a stock cam may be the easiest and most sensible solution in the long run. (Check out the Knowledge Base for discussions on solid lifters: You may be wise to replace the tappet rollers while you are in there, if they are not fresh ones already.)

The best way to measure clearance would be to trial fit the cover with a glob of modelling clay at the problem areas. A rule of thumb is .060" clearance just about anywhere there can be a 'collision'.

You will find discussions about cover gaskets in the Knowledge Base I'm certain. Grinding covers flat first, even brand new ones, is a matter of course.
I endorse thin gaskets, just like the Factory.

....Cotten
PS: I'll bet you find your valve adjustment is a tad looser now that they have made some clearance!

[VT]

(blue) Teflon head gaskets are great for Pans. The cylinders already have the fire ring at the top (knuckles cylinders don't, so they get the steel-crimped fire ringed gaskets). You might want to use the thick gaskets, since they're more absorbent of Pan cover bottom irregularities.
15 in. lbs. is the torque spec for the (12) D-ring screws.

[mbskeam]

grind the weld off, it wont take much, you can use clay to see how much clearance you have, some rockers have more weld than others.

mbskeam

[56pan]

When you say to use clay just how do I go abut it? I realize I have to put the clay on the cover but do I need to remove the valve so I can push up the rocker arm and how do I know how far the pushrod will lift the rocker arm? There's probably a simple answer but ?????? Please bear with me and I'll eventually get it. Thanks guys.
Bill

[Guest]

Isn't this what happens when the valve seats are sunk in? May need an oversized valve and a valve job.

[Cotten]

Guest!

When one end of the rocker arm goes up, the other goes down.
So when valve stem protrusion raises the arm on the 'left' side, it lowers it on the right, or pushrod side.
This is why some high lift cams must have the valves sunk.
A lot of heads were boogered by cutting the spring deck down (a Manley misformula) before alternative collars were produced.

Since cover interference is most common above the pushrods, I assumed that is where Bill meant.

Bill!
Is it?

The clay thing is always a matter of observation and patience.
I suggest globbing it upon the rocker arm first, as sticking it upon the cover may be difficult.
After making an impression by forcing the arm upward with a pushrod, the thickness of the clay can be observed by slicing through it with a blade.

Let us know how it goes... I've never done it!

...Cotten

[Panacea]

I can see where 56pan would have a problem with the clay method, the head would have to be re-assembled with the pushrods then turn the motor over so the correct "lift" is applied by the cam. Not really a "workbench" deal. I suppose a couple head bolts would hold it down well enough to test it out. The actual clearance is already evident in the dented cover. Must have been a hell of a racket! Mike

[Cotten]

Mike!

Since the upward travel of the pushrod end is governed by the valve stem on the other, just forcing it into the clay until the other end bottoms out should give a reading. (If the cover doesn't stop it first!)
It shouldn't take a full assembly, just turning the head upside down on the bench should do.

They never seem to make noise even when the spring collars are eating their way into the covers!

...Cotten

[56pan]

Thanks guys. It is the pushrod side by the way. I filed the weld point on the rocker arm and I think that will do it. It was sticking up pretty far. I'll let you know how it goes once I get my new parts and get them installed.
Bill

[56pan]

Well, I finally got everything together and fired it up. No problems. The new Paugho rocker arm covers were about 1/2" taller than the ones I had on before. I rubbed them on emery cloth until they were flat. It's a good thing I read about this in this forum because those covers were really out. Thanks everyone for your help.
Bill

[VT]

unevenpn01gh3.jpg

I found my OE cover on '50-54 heads (right) to be shorter than a Kick-Start (vendor) cover on a set of '58-62 heads. The K.S covers (which had 12 perfectly matching screw holes) is about 3/16" higher than the OE cover. The bubble on the level is an indication.

unevenpn02la3.jpg

The bubble is level now. The reason it looks a quarter bubble up is because the table is sitting on a concrete slab that has a 1/4" per foot drop and had to be compensated for.

[Guest]

the difference is the heads themselfs. the pans are the same.