I did too much reading this winter and I have considerable doubt about the setup of my rocker arms. I really could use some clarification before I continue my project... here is what I have done and what my concerns are.

Last year I started a supercharger project on my 2005 Corvette LS2. It turned into a heads/cam/supercharger project after it got way out of hand. My biggest concern throughout the project has been longevity since I now have (what I consider) so much money into this! The specs of the cam are 223/235@.050, with an advertised duration of 274/285, and a .625/.625 lift. I was concerned about the LS2 lifters, so I installed a set of Morel 5206 linked bar lifters. When I pulled the heads I was concerned about exhaust valves being too small for the supercharger, so I took the 243 heads had them lightly ported and had Manley Elite Series Racing valves on the exhaust side, and had the intake valves lapped. Before I put the car away for the winter I installed the heads, stock rocker arms with trunion upgrade, and buttoned it all up. The car has not been started.

I didn't do anything special other than a trunion upgrade. I didn't shim the rockers, nor did I check the wipe pattern on the valves. I began reading over the winter that although you can run the stock rockers to .650 lift after about .588 lift they tend cause the bronze valve guides to wear, and the valve tips to wear as well. I am short an arm and a leg due to what the machine shop charged me for the exhaust valves and I sure as hell don't what to have to pull these heads again to replace the guides. What are my options here? And if the general consensus is to stick with the stockers; how do I set these up PROPERLY? As I said before longevity is my main concern.

DG

 

In case you were interested I currently have part Lunati Part #73925K1 Double Valve Springs Installed on my cylinder heads.

Valve Spring Specs:

O.D. 1.306"
I.D. .676"
Max lift: .660"
Seat load: 153 lb/in at 1.810"
Open load: 400 at 1.150"
Rate: 379 lb/in
Coil bind: 1.100"

DG

 

id suggest factory rockers with the trunion upgrade. Stock rockers are good up to about .630 lift and youre under that so youre good there. The factory rockers should do everything you want, while being lighter than rollers, and costing a whole hell of a lot less.

 

I have seen many threads on this beating up valve guides, and valve stems. This just makes sence with no roller to prevent friction. Is amazing how many people will lose sleep over ebay headers, and headstuds, and not worry about the moving parts of the valvetrain. I would recommend using roller rockers. They may be a little heavier, but with less friction and worn parts.

 

if he had bronze va;ve guides with true aftermarket castings I'd say go with rollers as well but with factory heads I dont think he really needs it. His lift is under .630 and his valvetrain isnt all that heavy. if hes got the $1000 for some nice rollers then by all means have at it.

 

Stock GM heads come with powdered metal guides, unless your machine shop replaced your guides they should be powdered metal? Stock rockers do scrub the valve tip after .600" lift give or take.

The key to valve tip durability when using stock rockers is to run less than .630" lift, run less than 400 lbs open spring pressure, and use oil with the zinc additives, with the oil possibly being the most important in that list.

My Platinum springs work perfect with stock rockers and in the spintron testing that I was involved in worked best of all the springs we tested, even springs that had more open pressure. http://www.briantooleyracing.com/660...l-springs.html

I hope this helps!

 

My valve guides are stock.... didn't realize they were not bronze. Looks like I am just scrapping by with the springs rated at 400lbs and the cam at a .625 lift.

Assuming that my measurements have changed since stock (and they have), with the morel 5206 lifters, the and they aftermarket exhaust valves I am running a set of Lunati 7.325 pushrods. The only thing I did was torque these rockers down to 22ft/lbs and called it a day. Is their anything in particular I need to do to set these rockers up properly so I do not expedite the inevitable valve tip wear?

P.S going to be running Joe Gibbs LS30 motor oil

DG

 

Brian what oil and additive are you recommending these days? Chasing oil is a never ending adventure it seems

 

I was looking for a little more information about setting these rockers up "properly"

DG

 

If you're sticking with stock rockers then the position that GM has the stock rockers at is about as good as it gets. The last thing you want to do is shim stock rockers. Shimming them may show a decrease in swipe pattern, but it actually INCREASES the amount of scrubbing.

A stock rocker rides on the valve tip just like a rocking chair rocks on the floor. It starts on the intake side of the valve tip and rocks all the way to the exhaust side.

Stock rockers are designed to work in a "half arc" meaning that if you visualize the motion of the rocker tip, it works in the first half of an arc. As lift increases past .600" lift the rocker tip starts arcing back towards the intake side of the valve. For roller rockers this is very desirable, it makes the contact patch more narrow. But for stock rockers it's a disaster because the rocker simply spends more of it's cycle dragging across the valve tip. So shimming up roller rockers makes sense. Shimming up stock rockers is one of the worst things you can do for durability.

Pushrod length on a bolt down LS head has zero effect on rocker geometry.

I hope this helps.

 

Push rod length... uffff Ive had that argument too many times. Some people just cant get it through their head that length of pr on a fixed base rocker only affects preload and has nothing to do with rocker geometry.

Aside from Jessel are there any aftermarket roller rockers actually worth running?

 

IMO stick with your stock rockera and add some LPE rocker stands for more rigidity. I'd also buy some ZDDPlus an add it to your oil (4oz) at every oil change, a 5 pack cost me $55 shipped. This way you can use any synthetic oil you want.

 

Well I guess i am done then. Just have to put all the hoses on and the radiator back in. Thanks for the tech support.

Brian, I have read many of your posts and have based most of the work I have done so far off of them. Its great that you were able to post in this thread. They only thing I can't seem to wrap my mind around is how the rocker movement on the valve tips just sounds so destructive, yet everyone continues to agree the stock rockers are the best. Doesn't make much sense.

I know I am beating a dead horse with this one, however I have one last question. In addition to your threads, I have been reading a lot of threads that vettenuts has posted. My last question; if shimming the rockers is bad because it creates more wear, then what is the point of even checking the wipe pattern if you shouldn't adjust it anyway. My previous questions were all based off the posts vettenuts has made in regard to checking wipe pattern and trying to get the stock rocker arms to have a centered wipe pattern. Well if you shouldn't shim them, then how do you achieve this?

Sorry for all the questions, but I am really interested in making sure I have all my bases covered. I am also the type of person who wants to understand everything I am doing and the reasons why. I do appreciate your patience and education on this subject.

I did not shim the stock rockers, just torqued then to 22ft/lbs

As I mentioned before I will be using Joe Gibbs LS30 motor oil so I shouldn't have to add ZDDP.

Thanks guys,

DG

 

On my latest build I did notice some VERY slight pitting starting on the valve tips again after about 12k miles of running using the castrol ow30 but the internals look SPOTLESS, literally like new so I will keep running that oil but me thinks I'll be using that additive on every oil change moving forward thanks for the pointers fellas. I should note I only did one oil change last season on those 12k miles. buzzed to 7500 on the regular too

As for rockers? I've seen SOOOO many threads/posts with failed aftermarket roller rockers I'd take advice from Tooley and a handful of others if there is an aftermarket rocker worth running but thats it. Plus Ive only seen a handful of issues with stockers and more importantly my experience with them has been great. I put on lots of miles too and they are not kind miles. ( stock trunions here )

I dont run donkey cams though which prevents the need for them and makes life a lot easier on the rest of the engine. I almost took the bait last time round and went BIG STICK but thankfully I was talked out of it by PatG

As for LPE stands? Hmmm.... milder cams I dont see the need, big cams put a hella lot of load on the little rocker arm bolt with those massive springs so adding beef there is WISE me thinks. LPE has a great rep too

Cams.... tricky business, rife with compromise at every angle, er degree

 

^ I should note when I say slight I mean SLIGHT. Two valves of 16 with single dimples in the center of the valve around 1/4 mm > in size. Slight, but there so additive goes in and I'll check this time next year again and see how they fare

 

The oil out on the market now "meets or exceeds OEM specifications." What they don't tell you is that it meets or exceeds OEM specifications for brand new vehicles. I am going to ball park 2009 and newer, in most cases. I always thought "meet or exceeds OEM specs" meant this is the latest and greatest and far exceeds the "quality" of the previous part (in this case oil). However that is not the case when it comes to oil. Specifications on oil are not related to quality of the product in relation to how it runs in the vehicle. Specifications of oil seem to cater more to government EPA standards. Sure the oil Mobil 1 and most the other generic brands are creating oils that last far longer, don't break down as quickly, and remain stable at high temperatures and pressures; and I do appreciate that. However even in the newer vehicles, the oils lack anti-wear additives, mainly zinc which do not help longevity of the vehicles engine. Thus in our cars, LS1, LS2, and LS3 it is better to run a higher zinc, older oil. I am currently running mobile 1 high mileage in most of my vehicles. I forget the ppm of zinc but it is more than the newest dexos oils which have barely 800ppm if I remember correctly. High mileage oil is intended for older vehicles that require more PPM. Unfortunately there are also undisclosed supposed-ed "seal conditioners" they include in their higher mileage oils, and I have not been able to find out exactly what they are. In addition, keep in mind to many PPM of Zinc is just as bad as too little. To little will cause what you are seeing on your valve tips, and too much will cause bearing wear. If i remember correctly (don't quote me), and ideal level for our vehicle is between 1400-1800ppm of zinc. Keep this in mind before you go crazy dumping in ZDDP. I am going to try using a boutique oil such as Joe Gibbs, or Amsoil which is supposed to cater more towards the needs of our vehicles and less towards government standards nobody cares about anyway. And they are considered high zinc oils.

That's my $0.02, hope it helps,

Now back to my question......................................

DG

 

If they are new heads or milled heads then sure yeah check everything it cant hurt. So long as the swipe doesnt go off the edge of the valve stem tip I say your as good as its going to get without going to Jessel etc. If the heads havent ever been off and your just installing the trunions then its a waste of time to check swipe pattern. Theres not much you can do about it anyways unless as mentioned messing with the stands/shims.

On install put a dab of decent non fiber grease on the valve stem tips and on the rocker tip and a dab of red locktite under the rocker arm bolt heads ( clean em with brake clean first ) then install them. If your heads have been ported into the threads of the rocker arm bolts coat them with Locktite #2br

Thats still a pretty big cam imo so Id run it this summer and check it over the winter by pulling the valve covers and a few rocker arms and checking things out for safety.

Hope this is of some help. Thanks for the oil advice.

 

Thanks for the advice. I think this is my only option. Run it for like 15-20K miles and then pull the valve covers and check it all out. I know I checked the wipe pattern and it was "ok" (very wide but mostly centered), however I can't remember if that was done before or after the trunion upgrade. I really don't want to pull this apart yet again and have to install checker springs after I got everything back together, ESPECIALLY if there is nothing I can do to change the position of the rocker arms anyway!

Just for reference... The stock 243 heads where pulled, and they were milled and ported. New exhaust valves were installed (Manley Elite series race valves). and a complete valve job was done. New Morel linked bar lifters were installed, new push rods, new springs, retainers, locks, basically new everything... so yea the geometry is nowhere near stock.

DG

 

None of that should impact rocker arm geometry in terms of wipe pattern thats fixed to the head, the checking is to make sure they are as they should be. I think you'll be okay for the season or more but I would check it after this season or if any noises crop up

 

I know, I just figured I would post some details so you can see I how far I went with this.

Like i said, the wipe pattern was OK (before/after?) the trunion upgrade. Either way seems as though there is nothing I can do about it anyway, so why recheck it.

In my posts above I was just interested in the differences in opinion on the importance of wipe pattern as I have seen a couple of other active forum members who advocate checking the pattern and then shimming. After Brian's post though i see why this is a poor idea.

DG

If you have a minute take a look at my thread on CF... you can access it through the link in my signature. It outlines everything I have done.

DG