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Broken Rocker..now lifter collapsed..

9K views 40 replies 5 participants last post by  Docc 
#1 ·
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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#2 · (Edited)
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.
 
#3 ·
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...
 
#4 ·
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.
 
#5 ·
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..
 
#8 ·
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.
 
#10 · (Edited)
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
 
#11 ·
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.
 
#13 ·
Docc said:
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.

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.
 
#14 · (Edited)
ericnova72 said:
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..
 
#15 ·
Cobalt
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..
 
#16 ·
That GM lifter you have with the seperate hard foot on the bottom of it is a very desirable piece as far as that end of the lifter is concerned, they just put a clip in it that won't withstand valve float or running the lifter plunger preload too close to the top of its travel.

Practically every SBC since the beginning with hydro lifters has used this lifter style with the wire clip and failure isn't a big problem. The clip failure you have has been known in performance circles for many years and is just from the two reasons I gave before. If preload is right and valve float is avoided they will last forever practically. This is one of the preferred hydraulic lifters in some very good circle track engine shops and they run stuff pretty hard, if that tells you anything about the quality of this lifter.

Run with the correct preload they are fine and I would do exactly as Cobalt suggested above - fix them back to stock or find a better clip for them, either way, but keep them. They are a really good part.
 
#17 ·
OK..

Then that's what I'll do.

I'll number them so I know where they go. Find wire clips or better if available. Set then 1/4 no lash tight.
Replace the damaged one as it looks like the cup is a little mangled. Do the new cam break in with that one..oR

See if I can rebuild that lifter and set correctly..and keep rev reasonable..

I really can't say i have banged on this motor much..I do use it more like a road racer on our open roads...as that is what it was when I bought it 37 years ago.

I was a solid lifter/4spd type always..more comfortable setting solids than Hydraulics..
Even as a Jag tech with OHC..I feel comfortable with the precise setting. The "1/4 turn past zero lash" just seems odd to me..but I'll learn. I understand about what pre load is..just "feels" odd to me..
 
#18 · (Edited)
I've got to say I just love that body style Jag as a hotrod like you have. Beautiful styling and quite sharp looking when you get rid of the overabundance of chrome (IMO) that was common to the Fifties era cars. Would live to see more pic's of it.

One of those "someday" projects I'd like to do if I could find a reasonable priced body would be to do one with flared fenders and 8-9-10" wide low profile rubber on all four wheels. All I need is the good body, don't care a whit about the rest, I'll build it. :thumbup:

Your avatar pick is a lot of the look I like, just needs the road race flare treatment for me.
 
#19 · (Edited)
Eric

Mine was a C/M racer converted in 1957 to SBC. It raced until 1970. It was given to the anus of the universe who hated the car. I helped him leave "this POS **** hole" Tucson in 1973.
It was gutted interior..roll bar..aluminum bucket and very tired GMC 6..
It last raced with a 283..(301)..2x4bbls..

I brought it back to what it was in 1974..but with a 327..solid cam two fours..Warner T-10. It was white..



When I got it in 1973
 
#20 ·
Docc said:
OK..

Then that's what I'll do.

I'll number them so I know where they go. Find wire clips or better if available. Set then 1/4 no lash tight.
Replace the damaged one as it looks like the cup is a little mangled. Do the new cam break in with that one..oR See if I can rebuild that lifter and set correctly..and keep rev reasonable..
Reusing the body, at least, of the lifter w/the damaged cup will be the preferred way to go. Even if it means buying a replacement for that lifter and cannibalizing it for the cup.

Keep the plunger w/the individual lifters, they're carefully size-selected to have the correct tolerances when they're assembled. The cups, flapper valve, check balls, etc. are all "standard" and can be exchanged freely- it's just the plunger to lifter body that need be maintained together, just like the lifter itself to the lobe, except not as critical. The worst thing would be a 'tight' fit that- when up to operating temp- might stick and cause a tap, or a 'loose' fit that would bleed down excessively at idle, like a Rhodes lifter.
The "1/4 turn past zero lash" just seems odd to me..but I'll learn. I understand about what pre load is..just "feels" odd to me..
Actually, the recommended setting can vary between manufacturers as well as between the different types of hydraulic lifters. 1/4 turn below zero lash is a setting that will satisfy most if not all requirements w/o going too far and having them "pump up" excessively at higher RPM.

Sometimes, guys will zero lash hydraulics and leave it there. I prefer some preload, for obvious reasons- but for a correctly maintained engine and w/the internal c-clips, zero lashing is acceptable to most, more often in race settings as opposed to "weekend" rides.

I would do this- see what the recommendation is for the lifters you're now using AFA preload. If they call for something other than 1/4 turn, you can always try it that way, and see how it performs. If you feel the engine laying down at upper RPM, you might suspect the valve springs or that the lifters are pumping up.

Should be a FUN ride!
 
#24 ·
The radiator is a Griffin with electric fan. For summer here in AZ I add the flex to get some air flow in the compartment and force air out.

I was getting 60* higher under hood temps..mostly around the carb without the flex.
I tried without..but 4 months with flex in 110*+ is really the only thing that has kept fuel perc and some vapor issues away.

The electric fan cools well but doesn't introduce much air into the compartment...which is very small..with carb just under hood where there seems to be no air flow without flex.
I have been doing it this way since 1983..but I have seen pictures and reports of the fan coming apart.

I check mine often..but use it only 3 or 4 months a year.
 
#26 ·
Docc said:
Looks like at least four lifters are missing clips..pulling all this week..

Thanks for all the help guys..
The internal C-clip style clips should be fine to use as replacements for the wire clips- provided that the slot they fit into is a square sided slot, and not a rounded slot.

The clips should be available to you locally- I'd try places like a bearing supply house, or a place that sells just automotive and heavy equipment hardware (nuts, bolts, studs, etc.). The size is a 'standard' one and should be easily matched up correctly by taking a lifter body w/you to fit the clip to.

The ones I have are about 3/4" OD x 1/32" thick. Get extras in case one goes flying.

You will notice there's a 'sharp' side and a 'rounded' side to the clips. Install them w/the 'sharp' side UP, so they will less likely to pop out of position.

AFA replacements for the wire clips, I'd try the same places mentioned above. I'd also take along a good one to use for comparison.

Good luck.
 
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