First thing I would do is to determine if you really have bent push rods. If you do, the next thing to do is to determine why the push rod bent. If you have hardened aftermarket push rods and you do in fact have a bent push rod. There is a reason it would be bent.

They just "don't" bend on their own. A typical reason would be if the piston smacks the valve while its open, that in turn shoves the valve back up against the rocker arm and in turn it tries to shove the push rod back against the lifter and so on. Well obviously if the lifter is up and the cam lobe and the valve pushes back the weakest point is going to be the push rod so it bends. 99.9% of the time a push rod bends because of some mechanical interference, such as when a timing chain breaks and the engine continues to rotate a couple revs due to inertia, pistons come up and hit the open valves, bending valves and sometimes push rods.



I'm just saying that I have been using the LS7 lifters since 06 and have not had a single failure of any one of them that I have sold. **** happens and things break, especially in cars that are beat on. I don't care what kind of parts you use, things do break from time to time. I have seen $600 morels break, so even they are not fool proof. From what I have seen, the GM LS7 lifters have a proven track record for me. As I mentioned earlier I have several Z06 customers running their cars on the road course for 30 minutes at a time going as fast as they can, and to date have not had one failure other than the ones I mentioned and they weren't LS7 lifters.

Some have used the GM Cadillac race lifters, they fail as well. I know of two customers that replaced them with LS7 replacements. I used them in my engine and lost oil pressure on start up. Replaced the lifters with LS7 units and my oil pressure returned to normal. This happened in 07 after a head and cam swap in my personal Z06, tore my hair out trying to figure out where the oil pressure went.

On another note, if you think aftermarket rockers are the **** to use, don't count on it, I have three sets of yella terras on these track LS6 cars that has broke over the years. I tell the customers to stay away from them. Stock LS rockers are tough, I have never seen one break other than the 07 LS7 rockers spitting bearings out. Aside from four actual failures of these in LS7 engines only, those were the only GM rockers to have failed in my area that I know of.
If you want higher quality rockers step up to Crower or Jessel shaft rockers, however even those have broke. I don't even use trunnion kits, that was a hot seller when the issue with the LS7 rockers came about, I just replace them with new GM LS7 rockers. katech uses stock GM LS7 rockers in their track, and street attack engines all the time. If you were to buy a Katech track attack engine it would cost you $25K. Thats gotta tell you something if Katech is using GM rockers in their engines.

 

My pushrods cost less then 200$ if I remember correctly.. They were all custom due to the differnt lengths...you should be well under 1k if your rockers are good.... Just hope it all comes out ok and it just be a pushrod and it's not that bad... When mine were bent it fluterd really bad at about 5k..but drive normal and sounded normal when just driving it..k let me know.

 

I run the LS7 lifters on my 408 and also stock fuel rails and coil packs. Neither of those will gain you much if anything more than just looks.

 

Don't believe all the hype Dave. It's no biggie.

 

Just get it to Brandon's and pull it apart. Then you'll really know what you're dealing with. LS7 lifters all the way.

 

Hope everyone had a good 4th!

 

so if its not a bent pushrod, what else would it be?

Every once and a while when i coast in nuetral off the hwy and slow it has a hard time catching the idle and drops to like 300rpm and then shoots back up and idles normal.. if i turn the ac on while driving and not at a stop, the idle will surge when stopped from 300rpm to 1200rpm. never died but sometimes it worries me.. i was thinking it just needed a new tune.. with the present cam it has a 900rpm idle, not much lope but enough for me.. just some info i thought might help.

im ready to get this torn down and figure ish out

 

just got a text from last owner.. he said he doesnt even know what a solid cam is. the shop just told him they changed the cam and ported the heads after the rebuild.. should be a roller cam then right?

 

Yep on the cam and you might need a new tune if its doing that..but that could be a cam of worms if you know I'm saying..lol.. Just check it all out first man. Better to be safe then sorry.

 

So we got to ripping into the vette today. Looks like the rocker arms are mushrooming some of the valve stems. Not sure If it was caused by improper pushrod length or something to do with it having nitrous or what. We did however find out he has hardened push rods at stock length and stock heads and an ls6 intake. Overall though, I would say it was a good day of bs'ing and wrenching though.

 

dude, your the best! thank you for all your help so far brandon!

so im looing for some assembled heads but not too sure what im looking for. I want afr's but i cant afford them so they are out of the question..

the spark plug showed that they were running hot, gapped .062? I cant remember, gonna be looking into that later today when i get back from the river.

I have found a few sets of 241's, 243's and 799's.. but i dont know the difference between them and what I would need to change on them once i get them... will my bbk lt's bolt right up to them also? I will be putting the nitrous back on the car, maybe even going up to a 150 shot..

now if I pull the cam, how do i get the specs on it? should it be stamped somewhere on it? Then it seems that I will need to have custom length pushrods made (like tyler already said). will i also need different springs?

Soo, im looking into finding some heads that will come fully assembled fresh condition but if i need to switch springs then would i save money buying them bare?. I was looking at the comp cam gold roller rocker set just for fun, im not sure if i need to change rr's?
http://www.ebay.com/itm/Comp-Cams-Ul...-/380664385231

heres some of the heads i found quick on ebay, any of them look like a good deal or fit?

http://www.ebay.com/itm/111113970437...84.m1438.l2649

http://www.ebay.com/itm/290723245360...84.m1438.l2649

http://www.ebay.com/itm/271116803799...84.m1438.l2649

http://www.ebay.com/itm/heads-alm-ls-1-799-castings-new-same-as-243-Z-06-CORVETTE-/200938348372?pt=Motors_Car_Truck_Parts_Accessories&hash=item2ec8dbdf54&vxp=mtr

 

The plugs are tr55 and had a gap of .062". I meant to text that to you just so you could have it on hand but it looks like you remembered it. I would personally go with a 243 or 799. I am kinda glad we found your noise being a valvetrain issue and nothing with the rotating assembly.

 

yeah me too. I was getting pretty sick to my stomach till you noticed it.. Im just hoping that the pushrods caused it and theres nothing hidden once we get them off.. if i cant find any heads cheap and fast enough i might just buy new valves and springs and have some pushrods made and throw it all back together.

 

If he has excessive clearances that can cause the rockers to beat the valve stem tips up and cause the mushrooming. If the valves in the heads are aftermarket they could have soft tips that can also mushroom under the hardened rocker arm tips. The GM rockers are very hard. It would take a considerably amount of lash and quite a long time to beat the valve tips up to create a mushroom effect. Are all the valves beat up or just intake or just the exhaust? If its just one or the other I would suspect aftermarket el cheapo valves.

 

it was happening to both exhaust and intake but was more severe on the intake and driverside head. we we're thinking a few things, my aggressive cam needing different length pushrods and/or springs werent correct lift or both? im learning so sorry if im way off.. gonna try to get back over there in the next couple days to finish pulling heads and cam. i was told most companies stamp specs on back of cam.

 

Has anyone measured coil bind on this setup yet?

 

no, how do i do that and what am i looking for?

 

A VERY BASIC rundown is as follows;

Using a dial indicator on a mounting fixture....bolted to the head; Basically, you're wanting to measure the total travel of the valve (from closed, to open) to where the coils of the valve spring are compressed to their limit, then subtract ROUGHLY .060 (depending on max lift) as your target at full valve lift.

Again, this is a very GENERAL rundown....but if you're tighter than .050 at max lift, then it is something that needs to be more closely scrutinized.


Since your valves are mushrooming anyway, probably best to take the heads to a REPUTABLE machine shop...as they are obviously going to have to be gone through again. They can verify this measurement for you, and you can make a more educated assessment once you know for certain what the lobe lift/rocker ratio is.

 

thanks for the run down, im actually not planning on using the same heads, springs, rods or lifters so should i still check that or find the cam specs and get springs, valves and rods that are compatible for the cam? im looking for 243's or 799's right now, hopefully some fresh rebuilt and assembled.. once i get the cam out, i should be able to see the specs stamped on it, then i figured i would be able to just buy springs and rods that will work with it..

 

Being that this is such a screwed-up occurrence, I'd want to get to the bottom of the issue....just to make sure to avoid it next time. Nothing worse than having to go back....yet again...to get it right. Then again, you could just make damned sure (as you should anyway) that the entire valve train is set up correctly this time. Personally, I'm the curious type, so I like to KNOW what caused the issue to begin with.