Lost a lash cap on my 340, now what?

[HP_Cuda]

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.

 

Let me get something straight here, you used caps so you could get the correct lash setting versus getting the right length pushrods? As I have heard it the caps are meant for titanium valves, but I wouldn't go that direction. Imagine the whole setup at 6k rpm jumping all over the place unless you are spot on. This is why I agree with hemiken and just eliminating another variable. With all the wear on your harlands I would definitely have the harland guys take a look at them before reusing them.

[cudabob496]

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!

No, its a fact. On big block Mopars, rocker ratios other than 1.5 have caused valve train failures.
Fairly common knowledge.
So, I was suggesting that its possible the damage he is seeing could be due to a rocker ratio other than stock.

Yep, there are 5000 people in their 80's still smoking, and 50 million smokers that did not make it to their 80's.

[HP_Cuda]

Caps were the failure point.

Show me any literature that says its a common fact, otherwise its just your opinion.

[cudabob496]

Caps were the failure point.

Show me any literature that says its a common fact, otherwise its just your opinion.

Here's an example of one potential problem..

http://www.popularhotrodding.com/enginemasters/articles/hardcore/0511phr_ratio/

[cudabob496]

Here is another discussion from the web. Of course, its just his opinion.
(the rocker tip not centered can cause serious problems)

If considering a change to larger ratio rockers, you need to be aware of some potential problems. The most obvious are related to the additional lift - you need to make sure you have adequate piston to valve clearance, and that there is adequate clearance at full lift between the bottom of the valve spring retainer and the top of the valve guide. Another consideration is the springs themselves - there must be proper clearance between the coils at maximum lift to prevent coil bind, and the spring must be strong enough to prevent valve float. This is more of a concern with a higher ratio rocker arm because the valve acceleration and peak speeds are increased which will make the engine more prone to float the valves. The geometry of the valvetrain must be verified - the rocker arm tip must be centered over the valve stem at 50% of maximum lift (especially critical with roller-tip rockers).

[72cudamaan]

Here is another discussion from the web. Of course, its just his opinion.
(the rocker tip not centered can cause serious problems)

If considering a change to larger ratio rockers, you need to be aware of some potential problems. The most obvious are related to the additional lift - you need to make sure you have adequate piston to valve clearance, and that there is adequate clearance at full lift between the bottom of the valve spring retainer and the top of the valve guide. Another consideration is the springs themselves - there must be proper clearance between the coils at maximum lift to prevent coil bind, and the spring must be strong enough to prevent valve float. This is more of a concern with a higher ratio rocker arm because the valve acceleration and peak speeds are increased which will make the engine more prone to float the valves. The geometry of the valvetrain must be verified - the rocker arm tip must be centered over the valve stem at 50% of maximum lift (especially critical with roller-tip rockers).

These are all generalized points. Any valve train geometry needs to be set for it's maximum potential and any engine
is prone to the same complications with a higher than stock rocker ratio. Not just a big block Mopar.

[cudabob496]

These are all generalized points. Any valve train geometry needs to be set for it's maximum potential and any engine
is prone to the same complications with a higher than stock rocker ratio. Not just a big block Mopar.

I agree, every engine should be set up properly. But, at least in the past, it was a much more common
problem for big block Mopars to experience valve train failure when going to 1.6 ratio rockers.

[HP_Cuda]

These are all generalized points. Any valve train geometry needs to be set for it's maximum potential and any engine
is prone to the same complications with a higher than stock rocker ratio. Not just a big block Mopar.

 

Funny this is exactly what I said....

[72bluNblu]

Let me get something straight here, you used caps so you could get the correct lash setting versus getting the right length pushrods? As I have heard it the caps are meant for titanium valves, but I wouldn't go that direction. Imagine the whole setup at 6k rpm jumping all over the place unless you are spot on. This is why I agree with hemiken and just eliminating another variable. With all the wear on your harlands I would definitely have the harland guys take a look at them before reusing them.

No, I did not.

No length of pushrod will change the location of the top of the valve. Once the rocker is on the tip of the valve, that's it. You measure for the correct length pushrod to allow the correct range of adjustment on the rocker. Running a shorter or longer pushrod just changes the location of the adjuster (as long as you assume you're setting the same preload). Yes, running the lash caps does require shorter pushrods, but the pattern on the tip of the valve was why I ran the lash caps, not because I had short pushrods.

The Harlands are toast. At the very least, that set isn't going back on. I have heard NOTHING back from Harland Sharp, despite sending them a nice long email, with pictures, of the situation. I didn't even blame the rockers, because while I know the rockers failed, I'm still not sure why. I'm going to email them again, and call if I don't hear anything again. At this point I don't even care if they replace the rockers, but I would like to know if they've ever seen this before, and what they think caused it. Even if they blame me or my heads or whatever.

Caps were the failure point.

I don't think so. The cap can't come off unless there's clearance to do so. Even with .030" of preload, it shouldn't be possible. The cap coming off probably happened AFTER the roller tip pin broke, and allowed the extra clearance. Only other possibility is that the lifter leaked down, and on startup there wasn't enough pressure to keep the cap in place. But even if that happened, it does not explain the worn out rockers, just the lost cap.

Something else cause the wear on the rockers. Bad geometry (which I checked and ruled out), excessive spring pressures, or possibly insufficient spring pressures causing valve float or bounce.

[HP_Cuda]

"You measure for the correct length pushrod to allow the correct range of adjustment on the rocker."

So then I have to ask how far off were you when you didn't have the caps on?

[72bluNblu]

"You measure for the correct length pushrod to allow the correct range of adjustment on the rocker."

So then I have to ask how far off were you when you didn't have the caps on?

Not very. I've seen people run worse. The pictures I posted earlier show exactly were I was.

[72bluNblu]

Well, the heads are off and down at the machine shop.

After inspecting all of the rockers, I found that MOST of them had some amount of wear around the roller pin. Not sure why that's happening. I also did some more checking on my valve springs, as it was suggested on another forum that those valve springs were too light for my cam. As it turns out, they are. The mopar springs don't spec their pressures, but I found someone that actually checked them at the same installed height. Turns out they only sit at about 100 lbs seat pressure and 260 open, which is woefully short of the 120 lbs seat and 317 lb open Lunati calls for with the 60404. Guess that's what I get for not checking them myself. I hadn't experienced any valve float, but I'd been going pretty easy on the engine too.

So I pulled the heads. Cam and lifters look good, everything else looks good. My machinist (not the one that did the heads originally) is going to cut the heads for the Lunati double springs and check them out while he's got them apart.

Probably overkill, but without a clear indication of what caused the failure I'm fixing any and all of the possible issues. And I still haven't heard back from Harland after sending them a detailed email last week.

[cudabob496]

thanks for the update. Those are some weak springs! Sounds like you are doing all the right things!
Saw add for some springs which have a smaller diameter at the top, compared to the bottom. Maybe
something to consider.

[72bluNblu]

I thought about going with beehive springs, but they have to be singles too. The new Lunati springs are 1.44" in diameter instead of 1.5", and with the Crane ductile's it shouldn't matter anyway. Don't get me wrong, I'm sure I could find beehives that will do what I need, but at this point I'm just going to run the recommended Lunati springs. Just eliminate another variable. This is a street car, and the engine has already proven to be a brute in the Duster that it calls home. The Harlands were only on it because I got a heck of a deal on them from another member, and since it is a street car I'm going back to as simple as I can make it. Adjustable iron rockers, no lash caps, and the double springs listed right on the cam card. Not the fanciest rig, but hopefully nice and dependable. Since it will end up being my daily as soon as I get the bugs sorted out, that's the more important part.

[cudabob496]

I thought about going with beehive springs, but they have to be singles too. The new Lunati springs are 1.44" in diameter instead of 1.5", and with the Crane ductile's it shouldn't matter anyway. Don't get me wrong, I'm sure I could find beehives that will do what I need, but at this point I'm just going to run the recommended Lunati springs. Just eliminate another variable. This is a street car, and the engine has already proven to be a brute in the Duster that it calls home. The Harlands were only on it because I got a heck of a deal on them from another member, and since it is a street car I'm going back to as simple as I can make it. Adjustable iron rockers, no lash caps, and the double springs listed right on the cam card. Not the fanciest rig, but hopefully nice and dependable. Since it will end up being my daily as soon as I get the bugs sorted out, that's the more important part.

Yep, all that should do the trick!