Lost Lash Cap

[72bluNblu]

Ok, I did a quick search and didn't find everything I was looking for, so here goes.

I "lost" a lash cap on my 340. Was driving home and suddenly had a "tapping" valve train noise, exactly like a noisy (loose) rocker. Didn't lose power, didn't run rough, so I finished my drive home (I know, probably not the best idea). Less than 10 minutes.

Pulled the valve covers and found that #4 intake had lost its lash cap. I run Comp Cams .080" lash caps with my Harland Sharp roller rockers to correct my rocker geometry. I managed to find and retrieve the lash cap from the cam valley rayer:. Surprisingly enough, it was on the other side of the valley, between the lifters on #3. Nothing on the lash cap looks damaged, although you can see a slight wear pattern from the rocker on the lash cap.

Engine is a '68 340, I have a Lunati #60404 cam in it. It has Lunati hydraulic lifters, Smith Bros pushrods, Harland Sharp roller rockers, and the Comp .080" lash caps. The engine has 1,100 miles on it, 600 since the last oil change and rocker adjustment. I just did a quick check, but the rocker adjustment doesn't seem far off anywhere else. I haven't pulled the rockers yet, but nothing in the valvetrain looks broken or damaged. Obviously with the rockers still on I can't see everything.

This is the first time I've run lash caps on anything, so I've got some questions-

How common is having a lash cap come off? Is this something that happens from time to time, or is it usually a symptom of a bigger problem than just a loose valve adjustment? I know that its not unusual to need some occasional valve readjustment, especially on a new engine, but I keep thinking the worst. :violent1:

My plan is to pull the rockers, inspect everything for damage, replace the lash cap, button it back up and reset the valve adjustment. Is there anything else I should be doing, replacing, or checking before I get into this?

 

[72bluNblu]

Nevermind, I think I'm screwed. :banghead:

The rocker that lost the lash cap appears to have hit the spring retainer, its toast. Also, from the looks of the wear pattern on all the other lash caps, they were spinning. The lash cap on #4 intake (the one that got tossed) was not.

So now I have to figure out if I sucked a valve. The clearance from the rockers to the valves was tight, but it shouldn't have hit just from the lash cap coming off.

Sigh. :violent1:

 

[MOPARMITCH]

Ouch!!!

 

[mderoy340]

if your taking things apart you need to epoxy small coarse screens in the heads where the oil drains back. this should be done to any head running lash caps. you where lucky!

 

[72bluNblu]

if your taking things apart you need to epoxy small coarse screens in the heads where the oil drains back. this should be done to any head running lash caps. you where lucky!

So, is losing a lash cap like that common? I would think if something like epoxying screens in place is needed it must be a fairly frequent problem.


Anyway, regardless I'm out a rocker for sure. Roller pin is broken (but intact in the rocker), and the rocker made significant contact with the valve retainer. Also looks like it hit the lash cap at one point as well.

At the very least I need a new rocker. But in the last picture you can also see some marks on the lock. There's a mark on the valve from the cap as well, but it looks like it may have also been in contact with the lock. And of course you can see where the retainer was hitting the rocker.

Now I need to figure out what happened here. None of the other rockers have any indications of hitting anything. When I set up the valvetrain I didn't check the rocker pattern on every valve, I checked one cylinder and determined I needed the lash caps. But I didn't have any interference between the rocker and retainer on that cylinder when I checked it, but I was turning it over by hand. I also have a little stem height variation because the guy that did my heads knew I was going to be running adjustable rockers, so the stem heights weren't perfectly identical. Not enough to need different length pushrods, but not identical. I also measured the valve tips to make sure the lash caps would fit without hitting the locks, but there is a little variation on the lash caps and that was before I fired the engine.

So I guess I need to order another rocker, then remeasure everything to make sure I have enough valve stem for the lash cap and enough clearance to the new rocker.

Any other thoughts?

 

[72bluNblu]

I took a better look at the rockers themselves. I knew the roller pin was broken on the banged up rocker (#4 intake), but I kinda figured that was from after the lash cap left. Then it occurred to me that the pin breaking could have been the start of this whole mess. Then I noticed the side wear on the rocker on #4 intake, from the roller. So I took a closer look at the other rockers. #4 exhaust has a significant amount of side wear as well, and I found two others on the drivers bank. Closer inspection shows that all 4 of the rockers with noticeable side wear from the roller tip also have pin wear on the backside of the pin. Seems like something is flexing, causing the rollers and roller pins to eat up the rockers.

Also, I probably should have mentioned before that these are the old Harland Sharp design. The new Harland's are wider at both the shaft and the tip. I know they had some kind of issue with the older ones, but I thought that was just the adjusters. I changed the adjuster nuts to an ARP nut, the original 11/16" nuts that came with the Harlands were impossible to adjust on the car.

So, I'm beginning to think the rocker broke first, which caused the lash cap to go away. I just don't know why the rockers would be getting eaten up like that.

 

[moper]

I can't see the pistures on this PC - but - if all the parts are in right, the caps can't come out easilly. It sounds like what you say - there is an issue in the rockertrain. Are they HS shafts? What spring pressures do you run? What type of heads are we talking about?

 

[72bluNblu]

I can't see the pistures on this PC - but - if all the parts are in right, the caps can't come out easilly. It sounds like what you say - there is an issue in the rockertrain. Are they HS shafts? What spring pressures do you run? What type of heads are we talking about?

Yeah something is going on. The shafts are Harland Sharp, I bought the whole set up from Fishy68 like 6 years ago. But this is the first time they've actually been run.

I have Mopar 5249847 springs. They were suggested by the guy that did my heads, but I don't know what the spring pressures actually are (I know :violent1:. This was my first engine build). The springs are intended for Mopar cams with up to .535" of lift when installed at 1.7" which is where mine are at. It's a chrome silicon spring with a .207" diameter wire. It is a single spring with a damper. I know that Lunati lists dual springs for that cam, but the gentleman that built the heads had a ton more experience than me and said they'd be fine. Again, I know, not the best way to go about it.

The heads are 308's that were cut for 2.02/1.60 stainless valves and ported.

Not sure why you can't see the pictures, they're on photobucket. If you PM me I can email them to you as well, I was hoping you'd chime in on this one Moper. :thumbup:

Here's some pictures of the geometry before I added the lash caps, you can see the pattern was a little to the "outside" of the valve, which is why the caps came into the equation.

 

[KosmicKuda]

I can't see the pictures either. (not that I know much about valve caps anyway) But a childhood friend of mine that I only see a couple times a year had an issue with one of his HS rockers a few years ago. (514 C.I. Ford street car) Because they are local to us, he went directly to their office/factory. I don't know exactly what they did, but they took care of him. They are, or were, a small company and their old place was just a small cement block building without any visible clue about what was going on in there. They have since moved just a few miles east but I haven't seen the new digs.

Does it look like the shaft or roller overheated from lack of oil? And it would be interesting to know what exactly is causing the side scuffing. It sounds like you did your due diligence in setting up your valve train and you said they have revised their design. That tells me there possibly were issues with the earlier version like you have. You might check with them, offer to send pictures, parts, or whatever and ask for their analysis of what went wrong. Maybe they will offer to make things right with minimal expense to you

 

[72bluNblu]

I can't see the pictures either. (not that I know much about valve caps anyway) But a childhood friend of mine that I only see a couple times a year had an issue with one of his HS rockers a few years ago. (514 C.I. Ford street car) Because they are local to us, he went directly to their office/factory. I don't know exactly what they did, but they took care of him. They are, or were, a small company and their old place was just a small cement block building without any visible clue about what was going on in there. They have since moved just a few miles east but I haven't seen the new digs.

Does it look like the shaft or roller overheated from lack of oil? And it would be interesting to know what exactly is causing the side scuffing. It sounds like you did your due diligence in setting up your valve train and you said they have revised their design. That tells me there possibly were issues with the earlier version like you have. You might check with them, offer to send pictures, parts, or whatever and ask for their analysis of what went wrong. Maybe they will offer to make things right with minimal expense to you

I wish I knew what was going on with the pictures, they show up fine for me. I'll see if I can attach them as well, but they may be too big.

Nothing looks overheated to me, there's no visible wear on the rollers at all. The spring pressure is the only thing I wish I knew better, one of those things where I took the advice of someone without getting the information that I probably should have had. I'm not totally convinced that its the cause of this, but of course I can't rule it out because I just don't know.

I sent an email to Harland already with a bunch of pictures and as detailed an explanation as I could muster, but I haven't heard back yet. Fishy68 used them to set up his geometry, and then sold them to me un-run 6 years ago. So I would understand if Harland wasn't going to warranty everything.

Maybe this will work...

 

[72bluNblu]

And here's the pictures of the original pattern, before I added the lash caps....

 

[flyfish]

I can see the pics just fine....but I'm no help on why that lash cap decided to leave....I can tell you that with the lash cap gone, driving it for another 10 minutes didn't do the cam lobe any favors.

 

[flyfish]

Edit: I would check for a wiped lobe on the cam....that would definitely account for the lash cap flying off.

 

[72bluNblu]

I can see the pics just fine....but I'm no help on why that lash cap decided to leave....I can tell you that with the lash cap gone, driving it for another 10 minutes didn't do the cam lobe any favors.

Edit: I would check for a wiped lobe on the cam....that would definitely account for the lash cap flying off.

That was the first thought I had.

I went back and inspected ALL of the rockers for pin and side wear. As it turns out, almost all of the rocker bodies have some amount of wear at the backside of the pin and on the rocker at the side of the roller. Some are worse than others, and #4 intake was by far the worst. But only a few don't have any obvious visible wear.

I'm beginning to think that the roller pin let loose first, which allowed enough clearance for the lash cap to come off. Or maybe that's just wishful thinking since it puts the whole problem on the rockers and means my engine might not be toast. If it were just a wiped lobe, or a collapsed lifter, or bent valve etc, I wouldn't expect to see that pin and side wear on most of the other rockers. Valve float would still explain it, but I haven't noticed any, and I haven't spent any significant amount of time over 4,500 rpm, and its never been over 6k if its even been that high. Bad geometry would too, but I don't see that either.

I'm inclined to swap the Harland's for a set of Crane ductile rockers I have, re-check the geometry with the new rockers and go from there.

 

[bobscuda67]

I lost a cap on my car last year by over revving it. I didn't hurt anything, just put the cap back on. My caps don't rotate, there on the valve pretty tight.
I don't think you're supposed to glue them on the valve stem. If adjusted properly they shouldn't just come off.

 

[604B1duster]

Are the caps riding on the valves or the locks ?

 

[72bluNblu]

I lost a cap on my car last year by over revving it. I didn't hurt anything, just put the cap back on. My caps don't rotate, there on the valve pretty tight.
I don't think you're supposed to glue them on the valve stem. If adjusted properly they shouldn't just come off.

The lash caps kind of snapped on, although once on they rotated freely. I didn't glue anything down, I think the epoxy was in reference to holding in screens to keep the caps from going into the cam valley.

But I'm under the impression that they shouldn't come off at all, with bad adjustment or valve float being the only reasons that wouldn't involve broken parts.

Since I found wear on many of the other rockers, I'm suspecting the rocker as the problem. I think my plan going forward is to set up a set of Crane 1.5 ductile rockers, remeasure for the push rods, check the new geometry and go from there. The ductile shouldn't need the lash caps either, the Harlands are designed for taller valves.

Are the caps riding on the valves or the locks ?

They weren't when I installed them, I measured everything to make sure they wouldn't. But, at least on #4 intake it looks like the cap may have been lightly contacting the lock. You can see the circle where it was riding on the tip of the valve also though. But the insides of the other lash caps and tops of the other valve tips have a more significant wear pattern.

 

[bobscuda67]

Are the caps riding on the valves or the locks ?

Mine snap on really tight and there is clearance between them and the valve keeper. I cut them down by hand and checked the gap on each one just to be sure. Dropping a valve would ruin your day.

 

[72bluNblu]

Mine snap on really tight and there is clearance between them and the valve keeper. I cut them down by hand and checked the gap on each one just to be sure. Dropping a valve would ruin your day.

Yeah I hear that. If the lash caps go back on, and they may not if I change the rockers, then they'll get cut down to eliminate any doubts.

 

[moper]

I'm thinking it may be something else - not the rockers. If the majority of the rockers show the effects of side-loading on the roller tip - that's a symptom of a problem. the rocker is the point of failure - but it's not the reason for the failure.
Were the heads professionally done or something else?

 

[teringer]

another thing to check is to make sure all the valves guides are in line ,a little off will change your rocker contact point on the tip ,maybe why some of the springs rubbed the rockers, and others didn"t I have seen the stands cast off a little and the stock rockers work ok because of the larger contact point .1 or 2 guides could be off a little and the rest straight if guides were replaced

 

[femtnmax]

72blu - Ive been watching what your going thru, as I was considering running lash caps on a hydraulic cam.
Some folks say to only use lash caps on solid lifter cams because if a "weak" lifter bleeds down overnite, then when the engine is started the lash cap can come off before oil pressure forces the lifter piston to the top of its travel. I did an experiment on the 432 I'm building now....I bled a lifter down by hand and with the lifter piston at the bottom of its travel there was more than enough clearance to remove the lash cap.
I have had new out of the box name brand hyd lifters that bled down so fast you almost could not find 'zero' lash to set the lifter preload. The point I'm trying to make is a "weak" lifter could be part of your engine problem.
After your experience I am not going to run lash caps on a hyd cam.

I can see all your photos...looking at your rocker arm contact on the valve stems....yes the contact pattern starts near the valve stem centerline and travels toward the exhaust side of the stem....but Smokey Yunick in his book "Power Secrets" would say the contact pattern is fine without the lashcaps. He said the pattern does not have to be perfectly centered, and the pattern is acceptable as long as the pattern stays .02 inch away from the edge of the valve stem...which yours does without the lash caps.

The wear on the rocker arm bodies looks as you suggest...the roller tip shaft is flexing.
For my 432 I bought a set of the Crane iron rocker arms that you mentioned...the ratio came out more than the spec and they are said to be "bullet proof".

 

[Cudafever]

Is the spring to weak and lofting or bouncing, cause undo stress on the valve train?

You do have a cam with a vary fast ramp..................

 

[moper]

Is the spring to weak and lofting or bouncing, cause undo stress on the valve train?

You do have a cam with a vary fast ramp..................

^^ This.
You have the wrong springs for that camshaft. You do not use lift to determine if the springs are strong enough. You use the cam manufacturers requirements for installed height and spring rate, and match up what you want to use to those specifications. The MP springs are way light for a VooDoo type lobe, even a short one. Your head guy should have known that. Given the geometry issues and this, I'd have a better shop look at them. There's probably other stuff amiss there.

 

[IQ52]

Why do they make locks with a lash cap recess?