Technical Engine builders: Why is my new 322 breaking rockers?

Guys,
The fresh 322 in my Avatar is giving me some issue and I'm looking for some advice to help solve the problem.
I fired the engine and ran it through it's break-in 20-30 minutes without issues.
One week later warmed the engine up and after a cool down , and re-firing it broke an exhaust rocker on the driver side. It was audible, shut it down down right away. I replaced the rocker as I could not see anything really wrong.
After a couple hundred mile trip it broke two more rockers. This time intakes on the opposite bank. so something is definately screwed up. There was no audible noise when the intake rockers broke.

Here's a run-down on the motor
Brad Penn break in oil
Falcon rebuild kit (less cam / lifters)
322 Heads machined for 364 valves
New guides pressed in
New stock valve springs
Mild hydraulic re-ground cam (When Charlie Price sold regrinds) with new lifters
Adjustable pushrods.
'57 Buick 1.6 aluminum rocker arms (which, when they break show some voids).
Rocker tips were re-surfaced (Jigged on the ID bore). Not re-bushed
New Rocker shafts with no signs of wear or galling.
Umbrella style valve seals

I'll try to get some pic posted but the exhaust and one intake broke through shaft, the other intake broke more through the tip area

Any theories:
Guide clearance? Machinist says intake and exhaust guides "should have" plenty of clearance. Recommended is .0025 Ex and .0015 In. Is this typical of any early motor builds today (like sbc or sbf) or is this more clearance than a typical a typical motor build where a machinist might miss it on a Buick?

Could the two intakes have failed trying to overcome compression from a stuck exhaust valve?

If the valves were sticking valve wouldn't it be likely that It would hit the piston?

Upper cylinder lube? I did not run a lead additive/substitute. Could the valve seals prevent lube from getting to the guides? Is the new fuel not lubing my guides? I added some upper cylinder lube to the fuel but have not re-fired.

Researching the Buick forum:

Valve retainer to guide clearance. What is the liklihood that the valve retainer is hitting the guide?

Inner valve spring not in the pocket. Sounds like it's a snug fit, and the problem can be made worse if incorrect valve spring shims have too small of an ID causing the inner spring to hang up

Valve stem height should be =/- .050 from factory spec. If they machined the valve seat too deep it can change geometry enough where the spring retainer can actually contact the underside of the rocker. ( I need to inspect my rockers to see if there are signs of interferance in this condition.

Sounds like some Buick guides were non-concentric (for some reason) and new guides being concentric can cause problems. Anybody ever see this ?

I'm going to check oiling as well. Plenty of oil up top, and pressure is good.
Need to make sure the rocker shaft oiling holes are pointing down, check oiling to tips.

Anything else to check or look out for?

My friend Karl's 322 is running the same rockers, more agressive cam, same pushrod, valves. Only real difference is his guides are knurled.

 

Here are some pics when I picked the motor up.

 

Not familiar with nailhed Buicks but when I installed a .490 lift cam in my old Pontiac 370, I found an interference problem between the bottom of the retainers and the tops of the PC-style intake valve seals...exhausts were ok. I found out by assembling one cylinder with a light Isky valve spring and cycling the engine by hand. I was able to grind about 65 thou off the bottom of the retainers to give me almost 50 thousandths clearance....valve keepers don't stick down through the modified retainers and spring bind is not a problem with mine but you might check yours..

 

You would think something is hitting something. Mentioned retainer hitting top of valve guide or seal. mentioned spring bind. Big valves hitting piston top? Or cylinder wall? Not to many other things to run into.

 

Too heavy a spring, pushrods incorrect length?

 

In the first picture, the retainers look really close, if not touching, the rockers. May be just the picture. Any other variation in the valvetrain geometry could multiply the issue. I'd like to see what one of the broken rockers look like.

 

Yes, show us the rockers. I would take each rocker assembly off and look them over for any other contact marks, may catch them before they break. Curious, why the 1.6 ratio on the rockers, a recommendation from the cam grinder?

 

Coil bind maybe. If the rocker hits the retainer it usually just releases a keeper and drops a valve. Measure the space between the coils at temp and full lift.

 

It appears that you have adjustable pushrods. Some of which look as though they are adjusted way out. Maybe you should go back and rethink the settings. Could you have collapsed the lifters? Altered the geometry? I always use the soft spring method to look at how everything lines up before finial assembly. I'm not a big spender like Rocky. So I just use some springs that were between rockers on a 270 GMC.

 

Interesting, I'm watching!

 

Check with Nailhead Russ at Centerville Auto in Calif, he knows everything about Nailhead Buicks. I used the umbrella seals on a GMC I built that never had valve seals (like Nailheads) and ended up breaking push rods so, as mentioned before, that could be the problem.

 

Turn valve to max lift then pry down on valve to see if there is more movement available.

 

On my 322 the top of the valve guide and the valve spring retainer had very little clearance, My machinest had to cut the guides for clearance with a mild cam. The valve springs where binding also and we had to use performance springs for a 318 chrysler if I remember right. I ran the later high lift rockers also

 

The first one to break. Copied from his build thread.

 

Valvetrain disassembly is in order. There are gonna be witness marks for sure that will telltale interference. I would not think it would be to hard to find whats hitting from the looks of that rocker. Unless as posted before the pushrods are adjusted to deep into the lifters.

 

When the cam is at full lift, how is the angle on the rocker arm/push rod at the push rod pocket?

From the pics, it looks like the push rod angle might be a bit extreme when the rocker is up.

High ratio rockers would move the pushrod cup closer to the shaft, but make the angle more extreme.
At some point, you're trying to push the rocker cup away from the shaft instead of turning the rocker.

Are the shaft supports at stock height?

 

A valid point, but I think it was mentioned that the tip broke on one occasion. I could be wrong [have been many times] but I'm going with interference somewhere.

 

Agreed, It looks pretty obvious something is binding up.

I don't have any experience with these motors, but if the pushrod is set too long (as previously mentioned by a couple of posters) it's going to throw the geometry off. This could be compounded with high lift rockers, taller shaft mounts, and milled heads.

I would recommend close inspection of valve train, coil bind, rocker angle, push rod length, and checking piston clearance. (Lots of really good postings already for double checking)

If that fails to turn up anything, perhaps it's a bad casting on the rocker arms?

 

That really looks like that rocker went as far as it could go. Something hit something and it couldn't go any farther. The pushrod kept pushing and it broke.

 

My vote is on coil bind.

 

Hi Road

In your first posted engine pic look at the front spring on the right side, the retainer is not seated down on the top of the spring and looks to be up on the inside and hitting the rocker arm

I would not run the engine anymore till you find out why the retainers are not seated in the springs

Maybe your springs are a bit too small for the retainers and do not have enough travel for the 1.6 rocker as well then you get coil bind

You need at least .050 minimum of spring travel when the rocker is at full lift not to get coil bind problems

Like the others were saying your whole cam & valve train needs a good looking at by an engine guy, that has done that kind of checking and knows what to look for

 

times two

 

Also, it appears that all the lock nuts on your pushrods, are not locked down. This will allow the pushrod to change length as it runs. Which might be a problem.

 

They might not have set the lash yet, and BTW can you show the bottom side of the broken rockers as the end view does not show much

The under side is what we need to see as that is where the tell tale marks will be

 

Spring bind? Retainer contacting umbrella seal? I am going to suggest spring bind if you added much lift to the cam shaft.

Another thing to think about is how tight you have the valves adjusted. Too much preload on the lifters and too much lift will be your downfall. I got a 322 in the garage right now all stock and it is loose as a goose when the valve is closed. Granted it is too loose for my taste and it is a 55 year old mill but it is also an indication that Buick didn't intend for them to run tight.

 

Id like to see a pic like the first one with the valves adjusted and a front valve at full lift. Sounds like coil bind to me, I'd check those inners too.

 

Now that i blowed the picture up I see what D.N.D. is speaking of about the retainer not being seated. Not good for whatever reason. Good catch.

 

A lot of good information and ideas. I'm on vacation right now, and will be back this weekend to post some pics and updates.

 

Hi Motor

After yrs of building engines your eye's just get trained to spot thing's that don't look quite rite, and its amazing how the engine will let you know if something is wrong by feeling & looking at all the stuff when putting one together

Just have to be heads up and using your head all the time, just like spotting that tilted spring retainer since it is setting there looking back at ya saying hello here I am

 

Your right. I should have seen that when I noticed the retainer extreamly close to the rocker. Hell, some days I can't keep my socks up.