454 valve keeper fails, but valve not bent? - Page 2 - Chevelle Tech
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  #16  
Old Dec 11th, 12, 9:11 AM
jeff swisher jeff swisher is offline
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Default Re: 454 valve keeper fails, but valve not bent?

Sure glad you found it!!!
Now here is one issue but usually related to early mopar..
The mopar valve keepers will butt up on the ends and sometimes would pop out.
the fix was to grind some off the ends where they butt up and then it will fully engage the grooves in the valve.
Are yours butted up or is there some space between the 2 locks...space is good.

Now here is a pic of some stock type 7 degree next to the much fatter 10 degree locks.. these are the SBC locks.
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  #17  
Old Dec 11th, 12, 11:14 AM
CoolBlueGlow CoolBlueGlow is offline
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Keith
 
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Default Re: 454 valve keeper fails, but valve not bent?

Well, based on the pic you posted, it looks like i have 7 degree locks, After a little research I now understand 7 degree to be the "stock" locks.

I note that my current locks have lash cap recesses, but I am not running lash caps, which I presume to be fine on these stainless steel valves with stock GM long slot rockers. I have no idea why the head builder selected keepers with lash cap recesses. Perhaps that's all he had handy?

I did notice that the keeper that popped out had a definite wear pattern on the top shoulder of the keeper, so the rocker was obviously running on the keeper's shoulder - just that one keeper of the two on this valve. The other keeper on that valve has no such wear pattern.

I'm pulling the other rockers tonight and checking for wear there, to see if that same issue exists on the other keepers. If I find another one evidencing this issue, I'm going to swap all the retainers and keepers out for a non lash cap style 10 degree retainer/keeper setup.

Thanks for the picture and the clearance tip. It really helped!
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  #18  
Old Dec 11th, 12, 11:51 AM
jeff swisher jeff swisher is offline
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Default Re: 454 valve keeper fails, but valve not bent?

The reason the top of the keeper is worn is because it must go up to get out of the hole it was in..
On the way up the rocker rubbed and rubbed on it and made it look the way it does..
The rocker otherwise will never touch the keepers unless the guide plate breaks and the rocker runs off the side of the stem and pushed down on the retainer.

This will loosen the keeper and make work it's way up and pop out.

Could be that there was some binding in the guide plate or a stress fracture/riser on the plate and it finally broke and the rocker slid over and dislodged the keeper...

Just thinking here...
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  #19  
Old Dec 11th, 12, 3:47 PM
CoolBlueGlow CoolBlueGlow is offline
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Default Re: 454 valve keeper fails, but valve not bent?

Yeah, I found a mark on the guide plate that fractured, as if something struck it and caused it to fail. I presumed it was the keeper that came out and got lodged in there, but that's only a guess.

It was DEFINITELY the one that popped out first that had the wear pattern on the shoulder. I carefully labeled them separately the moment I removed the first keeper - before I even found the second one. No confusion there for sure.

Personally, I've never seen a guide plate fail like that, but I haven't raced in years, so I'm out of the game. Anyway, this one definitely failed...and I can't tell if that was first or last in the failure scheme.

Frankly, I'll just be glad to get the replacement parts in there and working and put this whole thing behind me. This is just a mild 454 for street fun and cruising. Seems like a lot of work to get a mild 454 going. I don't remember it being this hard back in the old days.

Dunno...maybe I'm losing my edge. :-)

Cheers,

Bryan
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  #20  
Old Dec 11th, 12, 4:47 PM
jeff swisher jeff swisher is offline
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Default Re: 454 valve keeper fails, but valve not bent?

I agree the old days were sometimes much better.
you had some great USA made stuff people that took pride in their craftmanship.
Now you have more of the people out to make a buck and this causes them to skimp a little here and there...Then we get to eat it..

Probably why i always like to use old good factory parts when i can..
You will be up and runnin' before you know it.
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  #21  
Old Dec 11th, 12, 8:16 PM
Tom Mobley Tom Mobley is online now
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Default Re: 454 valve keeper fails, but valve not bent?

maybe the guideplate broke first, allowed the rocker to ride on the retainer, act like a valve spring compressor, lock pops out. This can happen with bent pushrods too. I'd bet this is what really happened.
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  #22  
Old Dec 12th, 12, 6:29 AM
dreis454 dreis454 is offline
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Default Re: 454 valve keeper fails, but valve not bent?

If it were mine is be replacing everything between the litter and spring.

Pushrod,retainer,keepers.guideplate & rocker stud.
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  #23  
Old Dec 15th, 12, 1:05 PM
CoolBlueGlow CoolBlueGlow is offline
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Default Re: 454 valve keeper fails, but valve not bent?

Update on the mystery valve keeper failure:

Did the cylinder pressure test. I am cautiously optimistic. The valves seem not bent. There is a small amount of airleak, I presume it is past the rings? Anyway, I compared the airleak noise of the suspect cylinder's pressure test to two other cylinders. Sound and minor amount of airflow seems identical in all three. Definitely zero air into the intake. No gas blowing back out of the carb, etc.

Found two bent pushrods on the cylinder in question. The exhaust pushrod was very slightly bent, but the intake pushrod was REALLY bent, up above the guide plate - almost like the valve was incorrectly lashed or something?

I am now questioning my valve lash procedure.

For initial startup I lashed the valves with engine running and rockers clattering, in the usual way. After the initial cam run-in, I relashed the valves following exactly the GM 1966 service manual's instructions for final valve lash on a flat tappet hydraulic cam in an engine that is at operating temperature

The camshaft is a typical "torquer style" hydraulic cam. Sorry, but I don't have the cam sheet (give me a break...it's been 10 years since I bought it, o.k?)

The specs that come to mind are something like .530ish lift and something like 260ish duration. I'm no cam guru, but that does not seem very radical, from my understanding. I bought what was advertised as a typical towing and torque 1500-5000 RPM usable range grind. Again, hydraulic flat tappet cam here.

So, presuming that I didn't screw up the lash order (I didn't, o.k? I was fanatically careful about that) does it seem possible that my valve lash was GROSSLY incorrect? I just don't get how the #2 INTAKE valve bent a pushrod, but not the valve?

I am at a loss. I used GM's recommendation for initial and final lash... paraphrasing my procedure from memory, it is the old:

1. At initial start up, with rocker nuts backed off, run engine with valve covers off. tighten rocker nuts until valve train noise just disappears; reinstall valve covers, then run engine for initial valve train wear-in seating
2. Operate engine for at least 15 minutes, until oil temperature is at operating temperature (VERY IMPORTANT says GM :-)
3. With engine temp stabilized for at least 15 minutes and with each cylinder's cam lobe at base circle in order <using the GM description for how to determine this>, remove rocker covers, loosen the rocker nut until one can spin the pushrod with fingertips.
4. Tighten the nut until the pushrod rotation just gets resistance. This is "ZERO LASH" for a hot engine after initial run in.
5. Then tighten 1 additional turn.


O.K. I cheated and only turned them 1/2 turn...

Thoughts?


Keith
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  #24  
Old Dec 15th, 12, 2:36 PM
Tom Mobley Tom Mobley is online now
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Default Re: 454 valve keeper fails, but valve not bent?

the GM method? the dealership flat-raters method that never heard of a performance cam? Probably the underlying problem. Likely that one was loose enough to let the rocker arm get cocked, it's all downhill from there.

Don't worry about hearing slight hissing from the crankcase, it's normal. Just a little ring leakage.

ever heard of the EO/IC method that gets it right the first time, every time? That works longer duration cams with long lash ramps? This has been discussed at length here hundreds of times. I personally have been hammering on this for 14 years.

Check ALL your pushrods by rolling them on a flat surface like a piece of glass. if more than a few are bent replace the set. Check ALL your guideplates by removing them from the engine and inspecting them closely, like with a magnifying glass in good light. if any are cracked or bent get new GM guideplates. Check all the rocker studs for signs of wear in the section where the rocker ball rides or bent. If more than a couple are worn, replace the set with ARP.

Check the tips of ALL the valves while you have ALL this stuff off.

Stop trying to minimize the problem and the amount of work involved in fixing it. Seems like this is your MO here. It's going to leave you doing the whole thing again. Sorry, don't mean to be harsh but this is the way it comes across. Bullet dodging is not a reliable engine building technique.

Here's the EO/IC deal. It's written as if adjusting the valves on an already built engine but you can get the idea pretty quick.

Back off all your rocker nuts at least two full turns. Turn the engine with balancer bolt or remote starter switch till #1 exhaust just starts to open. Judge this by eye, you can see it the pushrod move up. Turn the #1 intake nut down to zero lash, confirm by rattling the pushrod up and down and spinning untill the play goes out. This is not particularly critical given the range of adjustment allowed. Adjust the intake to 1/2 turn preload. Go to number 8, turn the engine 1/4 turn, see the #8 exhaust pushrod start to move up, adjust the #8 intake as on #1. Then turn the engine another 1/4 turn, see the #4 exhaust pushrod start to come up, adjust the #4 intake as before. Go thru the firing order 1-8-4-3-6-5-7-2. Back to #1, turn the engine till the #1 intake valve goes to full open and starts to close, it will take like a full turn of the engine. Adjust the #1 exhaust like all the others. Turn the engine 1/4 turn, see the #8 intake go to full open and start to close. Adjust the #8 exhaust as before. Give the engine 1/4 turn, see the #4 intake go full open and start to close. adjust the #4 exhaust as before. Go the rest of the way through the firing order as before. Sanity check: when done all the nuts should be about the same height, all the rocker nuts should be about the same amount of stud sticking out. If any are way off do that valve again. It may be that all the intakes are different than all the exhausts, either higher or lower.

Or, keep doing what you're doing now.
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  #25  
Old Dec 15th, 12, 7:45 PM
CoolBlueGlow CoolBlueGlow is offline
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Default Re: 454 valve keeper fails, but valve not bent?

O.K. last update, and all good. Valves not bent. Engine reassembled and running perfectly. Lifters quiet, looking and acting like they should.

Minimizing the problem. No offense taken here, Tom. Not one bit! I pretty much came to the same conclusion on my own. Fixing the obvious failures and replacing broken parts is not the same as discovering the root cause of the failure. Anyone can change parts - discovering the reason behind the failure is what matters. That's why I've kept asking questions and questioning my own approach.

So, anyway, I quit half-measuring the thing, broke down the entire valve train, checked all the keepers, pushrods, rockers, etc. found the two bent pushrods on #2 and started from scratch on the lash. I abandoned the 66 GM service manual method - and did the EO/IC thing.

Funny thing happened - Tom it turns out what you call "EO/IC" is exactly how I've lashed my BBC builds in the past - all without knowing what the method was called. I didn't do it this time because I've always felt sort of guilty and shade-tree by doing it my made-up way. So this time, by golly "I was going to follow the rules" because "I should be extra careful and listen to the experts from GM"! After all, "Surely the factory service manual approved method must be better than my intuition" right? Wrong. If I had done it the way I've done it instinctively in the past (what you call the EO/IC method) I'm betting this whole mess wouldn't have happened.

Oh well. Water under the bridge. So, as I said, I've double checked everything, EO/IC'd the valve lash, and all is now good. It was instantly obvious when I started the engine that all was well. Quiet valvetrain and smooth idle, just like a mild flat tappet hydraulic cam BBC should be.

Thanking God that I re-learned this lesson without having to pull the whole motor apart!

Thanks to everyone for your input and assistance.

Keith
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  #26  
Old Dec 16th, 12, 3:57 PM
Tom Mobley Tom Mobley is online now
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Default Re: 454 valve keeper fails, but valve not bent?

Didn't mean to offend, glad you're not PO'd at me. I wrote that quickly at work, didn't check it for like tone and attitude which I'm usually pretty good about.

Glad you got it sorted and didn't have a major disaster on your hands.
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