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Old 04-30-2010, 01:18 AM
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Broken Rocker..now lifter collapsed..

Last Sunday out for a cruise. Motor running great..just about 2 miles from home. Up through gears (not jammin) everything fine. Come to stop sign..up through gears..everything great..motor strong as usual

In fourth gear..about 45MPH..loud BANG..knocking. I idle to stop about 500ft.



I was thinking rocker came off. Towed car home..pulled valve cover. #6 exhaust rocker is off..cracked and broken. Rocker is tight but since it's broken it's jammed against next valve.
I rotated by hand..removed rocker..and pushrod. Pushrod height was about like all others. Stud is fine..threads good.
Today I bought a new rocker and pushrod.

Turned motor till intake was compressed..tightened rocker until still very loose. Rotated motor and watched rocker move correctly.
Brought engine to compressed #6 intake and tightened exhaust again..feeling for up/down motion and spinning pushrod in hand.
Turned motor on starter with HEI disconnected..watched rocker moving open close just as it should.
Brought it back to Intake compressed..small tighten on exhaust..though to leave looser..start then final 1/2 turn if necessary.

Start engine..pop through carb, Pull cover..rocker completely off..pushrod just barely above head surface.

Could I have collapsed lifter ? Or..perhaps lifter was damaged when rocker broke ?

Motor is GM crate short block 350 Gen I
Cam is 24502476
Lifters 5232720
Camel Hump 186 2.02/1.60

Everything knew except..ROCKERS

When I was building this..i blew a couple disks in my neck and back pitching (baseball) the shop I was using helped me. They finished assembling engine.

I just went through all my parts receipts..all new except no ROCKERS.

They do not look like less then 10K miles.

Cam was broken in correctly (shop does many Hot Rods and exotics).

So..

I know it could be rounded cam. It could be rocker metal fatigue that bent rod and damaged lifter.
I am going to pull intake..hopefully it's a lifter that just collapsed or bleed down and not a cam round. The HEI may not come out without hood coming off..and a real chore to re-align.

Given that the rocker was moving correctly just before motor started..I am guess lifter. I don't think a cam can round in 2 minutes of idling..as it was showing correct lift when rotated on starter.

Am I naive..just hoping and not thinking this. ?

This car gets about 3000 miles a year. On the day it blew it still accelerated like always..quiet motor..very strong. Oil pressure 60lbs..25-40lbs at idle.

Any ideas...before I pull it.

Trying to think positive..two kids in college..and money is limited (duh)..

Old guy not real happy at the moment

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Old 04-30-2010, 01:43 AM
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What does the pushrod look like from that broken rocker??

It is far more likely that when the rocker broke it slightly bent the pushrod. They can get bowed almost 1/4" and still look like they are the same length if you don't pull it out of the motor and check for straightness. Then you replace the rocker and as soon as you fire the engine or shortly thereafter the compromised pushrod completely fails, breaking into pieces or bending considerably.

There is also the possibility that when the rocker broke the pop that happens blows the snap ring out of the lifter and when you start it back up the lifter spits its guts into the lifter valley. The pushrod being bent could also lead to it popping out of the lifter cup as soon as you fired it up.

Not much possibility that the cam to lifter interface is hurt but you will want to look at the bottom of the lifter . if it is just the lifter guts you can carefully reassemble it and it will be fine, but you might have to find a new snap ring for the top of it if it bent the original one or broke it.

Lifter plunger could possibly be collapsed, but that doesn't happan often and is more of a thing that happens to dirty lifters, they collapse down and can't pump back up because dirt has wedged between the plunger and the lifter body, locking it down.

Also examine the pushrod from the valve that the broken rocker wedged against, it is possible for that one to have gotten bent a little too from the interference.

Last edited by ericnova72; 04-30-2010 at 01:49 AM.
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Old 04-30-2010, 02:24 AM
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Pushrod has slight bends. Appears bent at top above guide plate and below near lifter..maybe just bowed along entire shaft.

I'll check better tomorrow.
I replaced the pushrod when I replaced the rocker,

Rebuilding the lifter could save me from a cam replace then as it is worn in to that cam lobe,,but replacing the lifter might eat the lobe as the surfaces won't mate as well ?

Eric much thanks for the reply..mostly I've heard "Cam dead"
It just seemed the pushrod dropped too quickly to be rounded cam lobe..and much more like you say lifter coming apart from side load from bent pushrod,,

Excellent idea about the adjacent pushrod..I'll check tomorrow. I'll tear down this weekend I hope.

I might even be able to sleep...
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Old 04-30-2010, 02:58 AM
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Cam you are using isn't anywhere near as aggressive rate of lift compared to later designs like Comp Cams Extreme Energy line or similar that people have so much trouble with going flat. GM's stuff is much gentler as GM takes long life much more serious and don't want to have warrantee claims.

If it looks good on the face but you do have to replace it I would only be like 10% worried that it might fail. If you have to go this route I would use a genuine GM lifter and use a zinc concentrate break-in additive and/or High zinc specific break-in oil like Gibbs break in or similar and run the engine just like you were breaking in a new cam - 20 minutes varying rpm between 2200 rpm and 3000ish rpm.

If the lifter spilled it's guts and broke some of the inner pieces but the body is ok you could also buy a new identical lifter(hopefully they haven't changed suppliers) and remove and swap the inner workings into your original body. I have heard of this being done just fine. you will just possibly need a dial caliper or a mic to verify the sizes of the plungers.

I can't see a cam lobe going flat in that short a time either, it does take a little time for that to happen and it doesn't happen without warning, the engine runs bad and makes noise as it wears away and rocker adjustment gets sloppy.

Hopefully you will have an easy path to repair this.
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Old 04-30-2010, 06:14 PM
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Eric

Came home a little early from work. Couple hours of wrenching..and all disassembled.

YES..!! Lifter guts laying in galley. Lifter looks excellent..no scuffing..lifter face looks perfect.
Snap rings..all broken. I recovered all 8 pieces (4 rings split). Matched them so I think I got all the metal.
Shut that motor off as soon as I heard that bang..

I think I can just replace the lifter..as it is GM Performance part..but worst case I'll rebuild this one.

Now..changing all pushrods..new rockers..and time for that dual plane manifold..

Going to spend some time cleaning out the engine..and use a magnet on the oil when I drop it. I don't think there should be a problem..but cut the filter apart to check there too..
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Old 04-30-2010, 08:16 PM
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Here's to hoping all goes well, sounds like it wasn't as bad as feared. Good luck with it.

I was going to suggest replacing all the rockers too, they would all be suspect to me now.
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Old 04-30-2010, 08:50 PM
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I may go with 1:6 rockers..but this is a 2300lb car..with 205/70 tires max fit..so there is a diminishing return on torque and HP..

Last edited by Docc; 04-30-2010 at 08:56 PM.
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Old 04-30-2010, 09:43 PM
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Yeah, I really don't like the lifters with the little wire clips for anything performance as they are easily broken when run with the lifter preload set to much to the light/low preload side, if the plunger is allowed to smack the clip it breaks rather easily, or if you have a valvetrain failure like you did the same thing happens when the preload is suddenly removed.

Not the end of the world however, you just need to be sure you are well into the preload when you reset the valvetrain, at least 1/2 to 3/4 turn preload, don't try to run them shallow on preload so to eliminate he chance of the plunger contacting the clip.

Just a side note, the better lifters have a full round tru-arc snap ring in them to prevent this problem, might be worth your investigating the possibility of a local industrial supplier getting you a correct thickness and diameter true snap ring to match the diameter of the wire clip, if one is even easily available, I have never personally checked for them. Don't sweat this idea too hard though, proper preload will alleviate this need.

Looks like you will be able to just reassemble things and be good. Be aware that the 1.6 rocker is made by making the pushrod cup closer to the stud, often requiring you to modify the original pushrod slot in the head to be longer if you are still running the heads with this slot intact. If you are running studs and guideplates these holes will have been drilled out bigger and should have plenty of room. The 1.6 rocker will probably add a little pep but don't expect a big change from them.
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Old 04-30-2010, 10:17 PM
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Quote:
Originally Posted by Docc
Be REAL sure that what you're seeing above in your photo is the actual entire clip- and not remenants of broken clips that still may be (just barely) holding other lifters together.

Shown below are some clips normally found in lifters, including the internal C-clip style used in better solid and hydraulic lifters.

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Old 04-30-2010, 10:19 PM
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Should there be four in just one lifter ?

I just checked..it appears several lifter have no clips.. I look better tomorrow..but unless one lifter has four clips..these have to go.

Thanks for the heads up..

All the clips I found just happened to be around the collapsed lifter..

I am completely cleaning out the galley tomorrow..and pulling a few lifter to see what's left in them.

I think these need to go.

Any ideas on these..
Howards Cams 91112 - Howards Cams Max Effort Hydraulic Lifters

$80 at Summit for 16

Last edited by Docc; 04-30-2010 at 11:23 PM.
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Old 04-30-2010, 11:16 PM
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One clip per lifter, I missed that you had 4 shown, some other lifters have battered the clip out. Rocker adjustment/lifter preload was set too close to the loose side or the valvetrain has been run into valve float.

How good are the valvesprings and were they matched to the needs of the cam when they were new??

The Howards Lifter is quality stuff, I have used Howards many times and they have a very good reputation. I don't know where you found the ones you showed in the picture, but www.competitionproducts.com has real good prices on Howards, they share the building with them and I have dealt with them many times. One of my go-to sources for parts.
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Old 04-30-2010, 11:22 PM
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These are what I have now..
$22 each at Summit
gm performance lifters 5232720
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Old 04-30-2010, 11:26 PM
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Quote:
Originally Posted by Docc
Should there be four in just one lifter ?
There is one clip, per lifter.

The broken clips shown could actually represent as many as 8 individual clips from 8 lifters.

Quote:
Thanks for the heads up..

All the clips I found just happened to be around the collapsed lifter..

I am completely cleaning out the galley tomorrow..and pulling a few lifter to see what's left in them.

I think these need to go.

Any ideas on these..
Howards Cams 91112 - Howards Cams Max Effort Hydraulic Lifters
Those look to have the good internal c-clips, but if you replace the 'old' lifters w/new lifters on the already run cam, you know the risks.

Before I would replace the old lifters, I would seriously consider keeping them in perfect order and replacing the clips- as long as the bottoms look good- then adjust the valves w/o any lash at start up, as in 1/4 turn below zero lash, so the clips don't get battered by the excessive clearance.

Good luck.
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Old 04-30-2010, 11:39 PM
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Quote:
Originally Posted by ericnova72
Rocker adjustment/lifter preload was set too close to the loose side or the valvetrain has been run into valve float.

How good are the valvesprings and were they matched to the needs of the cam when they were new??

Probably both..

Heads were done at a very respected circle track/drag/hot rod machine shop here. Highly recommended by race folks.
He did know the cam choice.

I blew out my back (EDIT: EX-baseball..57yr old..pitching coach..getting competitve with college players ) after getting most of the engine assembled..but some folks really helped me out..setting up the heads/valves...dropping the motor in while I left handed stuff..
When I screwed up my neck/back..I lost use of my right arm for more than four months. Did 8 months in therapy..finishing the Jag was part of that therapy..
I hadn't built a motor in 15+ years..so I am re learning stuff..and learning a lot of new things done differently now.

I'll never complain about the work that these folks helped me with..I could not have done it and they way it worked out..probably saved the project.

So I have some stuff to correct..that's what this is all about anyway..

Last edited by Docc; 04-30-2010 at 11:44 PM.
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Old 04-30-2010, 11:49 PM
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Given the relatively mild GM grind cam..would you think there is too much risk in going with the Howards..doing the complete break in..

Or can the GM lifters be fitted with circlips..?

I really don't like those wire clips..but if best..I'll rebuild them.

Really appreciate all the help form both of you.

Like I said..I was away for awhile..

Kids eat money..
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