Lost a lash cap on my 340, now what?

[72bluNblu]

If you're already inclined to get new pushrods I think a .060" preload might be better. IFIK that is the
standard anyway. I might be wrong. What say you Neil?

Depends on the lifters, but between .030" to .060" is common. I recall Neil suggesting .040"? Anyway, Harland recommended no more than a 1/2 turn preload, so .030" was how I set them.

I personally have never been a fan of lash caps, it may be worth your while to invest in another set of valves that fit your required length better also do away with the lash caps all together, eliminate them from any further equation.
[/quote

Me either. Although I shouldn't have to change the valves. The Harlands are designed for taller valves than stock, so going back to the Crane ductile rockers should also eliminate the need for the lash caps anyway. I'll still probably need new push rods.

[hemiken]

Me either. Although I shouldn't have to change the valves. The Harlands are designed for taller valves than stock, so going back to the Crane ductile rockers should also eliminate the need for the lash caps anyway. I'll still probably need new push rods.

Understandable, plus parts cost can get away on you. It would be good if the Harlands fit as original, but then again the advantage of a longer valve is a very desirable thing to have in my opinion

[brads70]

Just bolt these one and be done with it! 
http://www.j-performance.com/index.php?option=com_content&task=view&id=59

[72bluNblu]

Just bolt these one and be done with it! 
http://www.j-performance.com/index.php?option=com_content&task=view&id=59

Don't tempt me Brad!

The 308's on it now already flow 264 cfm @.500". 

But yeah, I would like the simplest fix, and hopefully that doesn't involve pulling the heads. I still need to do a leakdown on it, but its pouring rain so I haven't been able to get to it.

[cudabob496]

Going back and carefully inspecting ALL of the rockers for side and pin wear, I've found that most of them have it. A few don't, but a lot more have it than don't. If it were only one, I would be inclined to think I wiped a lobe, or collapsed a lifter, etc. But since its most of them to varying degrees, I'm thinking the pin just failed on the worst one. The broken pin allowed the extra space to kick out the lash cap, and here we are.

Or maybe I just want to think that because it means that the rest of my engine is fine, save for all of that damn aluminum circulating through it.

I'm more and more inclined to lose all the lash caps and install the set of Crane ductile iron 1.5's I have for the 318 I'm building. But I'll probably need new pushrods to do that.

I assume the valve train is getting adequate oil?

[73EStroker]

I run solid lifter cam, 273 rockers and lash caps in my 451. It's been to 7000 too many times no issues. Judging from what you say and the pictures it was either the rockers or are you sure the lash caps are not touching the locks. Does not look like a lot of valve stem sticking up there. All of my valve train was set up for everything I mentioned by the machinist. I praise your thinking for having adjustment though on the hyd lifters. I have been preaching that all along. You might get away with the pushrods with 273 318 rockers you have.
Keep us posted pls as this is an important post where others may learn something.

[72bluNblu]

I assume the valve train is getting adequate oil?

Yup, plenty of oil up top.

I run solid lifter cam, 273 rockers and lash caps in my 451. It's been to 7000 too many times no issues. Judging from what you say and the pictures it was either the rockers or are you sure the lash caps are not touching the locks. Does not look like a lot of valve stem sticking up there. All of my valve train was set up for everything I mentioned by the machinist. I praise your thinking for having adjustment though on the hyd lifters. I have been preaching that all along. You might get away with the pushrods with 273 318 rockers you have.
Keep us posted pls as this is an important post where others may learn something.

When I installed the lash caps I measured the valves and caps to make sure that nothing would touch. It was tight, but there was clearance and they didn't touch. Now that everything is disassembled, it looks like a couple of the caps may be touching the locks. #4 intake looks the worst, there's a wear pattern on the inside of the cap and the tip of the valve, but there's also a shiny spot on the lock and a little of the black finish on the cap skirt is gone as well, so there must have been a little contact there.

The Harland's are done, so moving forward I think I want to un-complicate my build as much as I can. I'll set up the Crane ductile rockers, and with any luck the geometry will work out without the caps. I'll just have to see if the pushrods are close enough to work. If not I'll measure for new ones. If I can get out of this with just the set of Crane's I already had and new pushrods I'll be pretty happy, it could have been a lot worse.

[cudabob496]

Yup, plenty of oil up top.

When I installed the lash caps I measured the valves and caps to make sure that nothing would touch. It was tight, but there was clearance and they didn't touch. Now that everything is disassembled, it looks like a couple of the caps may be touching the locks. #4 intake looks the worst, there's a wear pattern on the inside of the cap and the tip of the valve, but there's also a shiny spot on the lock and a little of the black finish on the cap skirt is gone as well, so there must have been a little contact there.

The Harland's are done, so moving forward I think I want to un-complicate my build as much as I can. I'll set up the Crane ductile rockers, and with any luck the geometry will work out without the caps. I'll just have to see if the pushrods are close enough to work. If not I'll measure for new ones. If I can get out of this with just the set of Crane's I already had and new pushrods I'll be pretty happy, it could have been a lot worse.

maybe the clearances change for the worse when the temp is hot?

[Chryco Psycho]

Sounds to me like the valve seats are slightly sunken so to match up the valve heights they trimmed the top of the valve stem so now the lash caps are touching which is what I saw in the pix , this is critical if non adjustable rockers are used but not so much with adjustable rockers

[72bluNblu]

Sounds to me like the valve seats are slightly sunken so to match up the valve heights they trimmed the top of the valve stem so now the lash caps are touching which is what I saw in the pix , this is critical if non adjustable rockers are used but not so much with adjustable rockers

Valve stems weren't trimmed. The valve heights are close, but not perfect. The gentleman that did the heads knew I was running adjustable rockers so the valve height variation was left alone.

There are a couple of valves were the caps look like they have contacted the locks, but they don't all match up with the worn rockers. I think that's mostly variation in the lash caps, when I installed them I did a bunch of measuring because some of the caps would clear the locks, but others wouldn't, even on the same valve. I didn'tnoon shave any of the caps down, but there were more than a couple that I couldn't use because the skirts were too tall.

I'm confused by all of this. I have a bunch of worn rockers. I have a few caps that we're touching the locks, but those caps were still touching the tops of the valve stems. And I have more worn out rockers than caps that were on the locks. But I also had decent geometry, and great oiling. And I still need to do a leak down.

I really just wish I knew what caused all this so I could fix it, but so far I have like 3 or 4 different issues, any of which could have caused the problem. Ugh.

[cudabob496]

so there's nothing about the older style Harlan rockers that could be contributing to the problem?

[cudabob496]

hmmm, bad bearings?

http://ls1tech.com/forums/generation-iii-internal-engine/1080744-problems-harland-sharp-stock-rockers-pics-inside.html

5/16 bolt weak link?

http://highperformanceolds.com/phpbb2/viewtopic.php?f=3&t=3900

[cudabob496]

hmmm:

http://www.forabodiesonly.com/mopar/showthread.php?t=39225

[72bluNblu]

so there's nothing about the older style Harlan rockers that could be contributing to the problem?

Oh there is, I'm really beginning to suspect that the rockers themselves are a big part of the problem, if not the whole problem. I just wish I had a "smoking gun" instead of half a dozen issues that may or may not have contributed.

I just don't want to smoke another set of rockers, or worse.

But I think I'm just going to end up going with crane ductiles, which should let me ditch the lash caps too. And then I'll just have to keep an eye on things to make sure.

[HP_Cuda]

Nice generalization there Bob

Smoking causes cancer but yet you see folks living into their 80's while smoking.

It's all in the setup!

on big blocks, rocker ratios other than 1.5, have been know to cause valve train geometry problems.