# lifter tapping broken rocker arm



## mike4387 (Sep 8, 2011)

so the car starts to tap really bad the other day so i pull the valve cover and this is what i find. i think the damage may be further, the engine still ticks even without the the rocker arms on that cyclindes taken off and also the pushrod for the intake side beside the broken arm is jammed and wont come out. A few other things to note car runs leans and wont go past 6200 rpms, so anybody know what happened and know the extinct of the damage, guess ill be pulling the head this weekend.

cams a custom comp cam, i believe lifters are stock


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## mike4387 (Sep 8, 2011)

Update I got the pushrod out of the hole and its bent it looks like an S. so just to refresh I got a bent pushrod on intake side of cyl 2 the rocker arm is fine. And iv got a broken rocker arm on exhaust side Of cyl 2 and the pushrod is fine. And no more tapping now the rockers and pushrods are removed. Ideas anyone what could of caused and is it possible the lifters gone? Also pressure tested the cyl and valves don't seem to be leaking
looking for some oem pushrods if anyone has any pm me thanks


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## Inprogress65 (May 18, 2012)

What kind of spring pressure are you running? Did you over rev it? The rocker debris could have potentially caused the bent pushrod if it managed to bind the intake valve/spring assembly. As to the rocker, thats a good one. Either something drove the pushrod through the rocker (valve float maybe?) or it may have been a material issue (porosity?) with the rocker to begin with. 

I have seen incorrect pushrod length put strange stresses on rocker cups as well? You may want to double check your geometry?

Just a few thoughts...


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## BearGFR (Aug 25, 2008)

Agree --- what were you doing/how were you driving it when it let go? How long have these rockers been in the motor? 

And did I understand you to say that the motor won't rev past 6250 NOW? With the damage? Are you outside your MIND???!!! You shouldn't even be running the engine until every last metal fragment from that broken rocker has been located, accounted for, and removed. Having broken metal fragments circulating around inside your engine is a "bad thing" and will likely do much more damage than just a broken rocker and bent pushrod.

I'd also be pretty concerned about the lifter and cam lobe on both valves, especially the one with the bent pushrod. All that force had to go somewhere.

Bear


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## Inprogress65 (May 18, 2012)

Good call Bear. At the very least you need to reconstruct the rocker from busted pieces (to account for all missing bits) and visually check the lifters and cam lobes. I'd also get a dial indicator on those two lobes. The easiest method would be to get a good pushrod and rocker on the two affected locations and measure valve lift at the retainer. Cam lobes will vary a good couple thousandths from one to the next but much more than say .008 and I'd start to be concerned. And if either has lost material don't bother tring to "bandaid" it and put it back together, the cams toast.


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## mike4387 (Sep 8, 2011)

ok thanks for the input guys, the rocker arms have been in the car since 07, and have around 5000 miles on em. I spoke with scorpion and they say it was the first version of that rocker arm and was prone to breaking very easily, so they suggest i pull all the old rocker arms and replace with the newer versions also upgrade the pushrods to some .80 hardened steel ones. They said that likely what happened was the exhaust rocker arm broke and once the cyclinder filled up with air it didnt have anywhere to go so the valve stayed closed and the cam pressed against the pushrod bending it. They said it no wonder it happened with me running a stroker motor, ls6 stage 3 head, the comp cam with .600 lift and a supercharger it put a ton of stress on the stock pushrods. will update once i get the parts replaced and see where i am at.. also going to check rod length to make sure the 7.4s are good.


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## svede1212 (Nov 1, 2005)

The newer Scorpions are supposedly better but I wouldn't run a low end aluminum rocker on my engine. Too many failures and you never see a steel rocker failure outside of the trunnion bearings. This could be a material defect or things like a lifter going or valve float that can make the end of the push rod lose contact with the cup on the rocker. That jack hammers it when it slams back into contact. What RPM this was at, spring pressure, retainer or valve weight all come into play


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## mike4387 (Sep 8, 2011)

car is set to redline at stock level, valves, springs, and retainers are all stock.


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## Inprogress65 (May 18, 2012)

It sounds like your on the right track now but I think you might want to add a few more things to your to do list. If you do in fact have a big Comp cam running on all stock valve train you might want to check you spring pressure and more importantly, your clearance to coil bind. You obviously have "enough" clearance as you have 5000 miles on this combo but you might be right on the ragged edge which may be part of your problem. I understand that you're still reving to stock redline but that cam likely has a much more aggressive ramp and may require more spring pressure to keep everything under control.


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## mike4387 (Sep 8, 2011)

Inprogress65 said:


> It sounds like your on the right track now but I think you might want to add a few more things to your to do list. If you do in fact have a big Comp cam running on all stock valve train you might want to check you spring pressure and more importantly, your clearance to coil bind. You obviously have "enough" clearance as you have 5000 miles on this combo but you might be right on the ragged edge which may be part of your problem. I understand that you're still reving to stock redline but that cam likely has a much more aggressive ramp and may require more spring pressure to keep everything under control.


thats what im beggining to consider, i just had it dynoed about a month ago and that might of weakend the everything a little. The bottom half of the motor is good, its forged ls series stroker eagle 4.0 crank, forged diamond racing aluminum pistons, eagle rods, arp rod bolts, and clevite main and rod bearings. should be okay on that end, i think ill start getting together some hardened steel push rods, and a stronger spring and titanium retainer combo. maybe upgraded valves and lifters as well. I got the replacement rocker arm in today and push rods should be here thurs, ima try to drain the oil and find all the rocker arm pieces, then check the lifter and reassemble to see how it runs wish me luck.


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## Inprogress65 (May 18, 2012)

Good luck, hope everything goes well. 

As far as the pushrods, hardened for sure. Additionally check your length and make sure its right before you order a new set. By that I mean watch the roller as it travels across the valve tip. It should start off-center to one edge while on the base circle (valve closed, no lift), move thru the center as you reach half lift, and run off the opposite side of center by the same amount as you reach peak lift. 

As for springs, I would get in touch with Comp and see what spring they recomend for your cam. 

Now titanium retainers on the other hand may not be worth the money to be quite honest. You're most likely going to stay with the same beehive style spring you're currently running. The concept there is by reducing the diameter of the spring at the top (the portion that sees most of the movement) you accomplish two things; one, your spring mass is reduced where it needs to be and two, you're retainer is now half the size (and weight) as a similar standard spring would need. At that point the difference in weight between the Ti part and the steel is quite small and if you're only reving to the stock redline you could probably save the money. That's just my opinion I'm sure some of the other guys have a few words on the subject as well.


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## Inprogress65 (May 18, 2012)

Then again, Titanium anything is always good for bragging rights!


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## Inprogress65 (May 18, 2012)

Here's a link to Comps website and a decent write up on checking pushrod geometry. Keep in mind that you don't necessarily need to buy the pushrod length checking tool should you find yourself out of spec You can build the tool using one of your old pushrods. Your geometry may be correct as it is using the stock pushrod, but it's such a simple check that it can't hurt. 

COMP Cams® - Pushrods


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## mike4387 (Sep 8, 2011)

Inprogress65 said:


> Here's a link to Comps website and a decent write up on checking pushrod geometry. Keep in mind that you don't necessarily need to buy the pushrod length checking tool should you find yourself out of spec You can build the tool using one of your old pushrods. Your geometry may be correct as it is using the stock pushrod, but it's such a simple check that it can't hurt.
> 
> COMP Cams® - Pushrods




ok thanks a ton man! glad i got good feedback on what to do and where to go, ill get a hold of comp and see what the suggest for springs and go from there on that, also will check pushrod length just to make sure that all is well there, hopefully i didnt damage anything further than the rocker arm and pushrod and ill be able to swap out the new stuff without getting into the head.


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## Beeroni (Oct 4, 2021)

I see this is an old post but wondering how did this job turn out? I recently got some knocking coming from my top end..😅 suspecting a broken valve spring,rocker and or push rod. Taking it in soon to find out.


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