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As some here know, I've been doing a lot of repairs on my LS7. Heads reworked by Tony Mamo, new cam, lifters, and running Yella Terra full roller rockers. I've run into an interference problem with them hitting the rocker pedestals! I have pics I'll post here. Basically, the pedestals are just a bit wider that the rocker openings. When bolted down, they bind and can't swing thru their arc. Really can't move at all. Tony says he hasn't experienced this before. Just wondering if anyone here has had this happen, and what resolution they came to. Pics have the interference area circled in blue.
NOTE!!!! The adjustable PR is on cylinder #1. Cylinder #3 has no "witness" gouging because I stopped after cylinder #1 had obvious problems. Interference isn't a lot, but it's enough!!.....
Just saying because i care, but you are throwing away more $$$ re-running those stock heads without a shaft system. Those roller rockers aren't going to do jack **** to make the guides last any long because the root problem is the pedestal on the head itself, not the rocker or the valvetrain geometry. At the very least, look at a Comp BSR shaft system which I think you can put some TS roller 1.8 rockets on them if you wanted full roller or just cut the BS all together and put a Jesel or TD shaft system on it and cut the pedestals off all together. Honestly, the roller rockers on a stock head is not even a bandaid fix. It may even exaggerate the problem as now you have a bunch more weight swinging around pulling on the pedestal. If Tony has so much faith in this setup, I would get a written mileage warranty on all the work with a $$ back guarantee...but that will never happen. Im just saying this because I know you want to bullet proof your setup, this isn't going to do that.
UPDATE!!!!! Let the arrows fly!!! The warning that some LS7 heads may need additional clearancing is, in fact, there. Yes, it's at the bottom of the page. Should it have been at the top of the page? Maybe. Should I have caught it? Definitely. Suck to be me? For sure, lol!!! See the attached pic. I still believe a bolt on should be a bolt on, but they do show the warning.....
One big problem is the heads are already torqued down on the block. It was one Helluva job to R&R the heads with the engine in the car. I'm not 50 years old anymore, and have no interest to R&R them a second time. These are supposed to be a bolt on setup. This should've never happened. There was absolutely nothing in the instructions about some LS7 heads may have a slight pedestal clearance issue, or I wouldve checked this on the bench. (YES THERE WAS-See pic above!!) This could've all been easily avoided by having .025" less material on each inside edge of each rocker body (making the "slot" .050" wider), and adding that .025" back on each outside edge of the rocker body, maintaining the strength. Nobody can blame me for being pissed at this development. But pointing fingers and crying about it won't help. Question is, what to do? I DO have a budget, which has been totally exceeded. So a Jesel/T&D setup is just not feasible. Do I return the rockers, and go with Texas Speed rollers, which look a lot like stock with a roller tip. Or a different brand? If I clearance the pedestals, how do you keep contaminants out of the engine? If I clearance the rockers with a slight chamfer, how slight? What distance of the arc should be clearanced? If I alter the rockers and one breaks, YT wouldn't cover it under warranty. How do you keep contaminants out of the rockers? Either way, if I keep the rockers, I'm looking at hand clearancing 32 surfaces, either both sides of 16 pedestals, or 16 rockers. Whatta mess......
I wouldn’t think clearancing .025 on the rocker would hurt anything.but when a man buys a part he wouldn’t think it needed to come with a grinder.
you might be able to use plastic on the heads and tape off the pedestals it worth a try.
sorry about your bad luck.the endless parade
Yeah, just whip out the Dremel and tape off the area around abd just touch it to clearance. Minimal material removal. I would send those YT's right on back and do the Comp BSR setup. JMO
I'm thinking about plastic garbage bags and having my shop vac somehow attached close by. Have to dig up the ear plugs for that one, lol. From what I'm seeing online, this is a problem very few LS7 heads have. Jeez, I'm starting to sound like G.M. P.R.!! To be clear, this is not entirely YTs fault. GMs inconsistencies on the LS7 heads seem endless. But one website, CNC Motorsports, stated that GM used 2 different foundries to cast these heads, and stated some interference issues have been found on occasion. They also stated that the boxes the YT's come in have special instructions addressing this issue. Mine did not, (YES, they DID! See pic above in post #4) and they came directly from Tony from YT in a never opened box......
Glad you found the notice... Sucks that it was after the fact.
I am not a fan of doing it that way but it is what is at this point. If you feel comfortable that you can tape things up and seal it off enough then take your time and proceed slow and cautiously as possible.
Since the gaskets haven't had a heat cycle they are still malleable enough to be reused. My preference would be to pull the heads to work on them. But then again easier said then done from the other side of the Key board...
After all that's has transpired on your end, I fell bad. Always seems like 1 Step forward and 2 steps back. If I was closer, I would offer to help.
Thank you for the offer. It has been a bumpy road, for sure. I haven't even mentioned my torque wrench fiasco. The damn rubber grip moved slightly while torquing the heads. With ARP studs, you're supposed to torque in 3 steps; 25, 50, and 70lb./ft. When it moved it gave a wrong value!!! First head was OK. I caught it on the second head, and had to do the passenger side twice!!! Craftsman tools are NOT what they once were. This one is 15 years old, and only built 2 engines with it before this one. This damn car is starting to remind me of Christine! It may even end up killing me. But one thing it sure as Hell doesn't do is fix itself, I'll tell ya!!!
There is a guy with some nice stock LS7 ones for sale in marketplace. .. Sorry couldn't resist.. I have been eyeing them. I have some Harland Sharp adjustables but going to run a hydraulic so thinking about going with some stock ones... keep my life simpler!
Brings me back to the T&D LS7 Billet Steel roller rocker arms. Those are a true bolt on that's steel and equal to if not lighter than the stock rocker arms. You should be able to clearance those areas by shoving some oiled up shop towles around the work area and take it one at a time. I had to clearance the corners of my Brodix heads for the T&D rocker arms with the heads on and in a 4th Gen Fbody so this should be a breeze. Grinder needs to get to grinding..
Last edited by 01CamaroSSTx; 09-01-2024 at 07:05 PM.
Copying and pasting the same response I left on the Corvette forum a day or so ago....didnt realize it was on LS1Tech also or I would have posted this at the same time
And I agree with the post above.....Grinder needs to get grinding.....LOL
Unfortunately these are the occasional pitfalls of hotrodding when OEM and aftermarket parts are involved and the OEM changes casting vendors or machining processes mid product run
Read my post below though if you have the extra minute but the abridged version is I have sold a bunch of these (dozens of kits in the last 10 years)....and this is the first time a customer notified me of fitment issues.
As most of you know the bulk of my LS7 business deals with my aftermarket design castings (TFS in this case.....and AFR when it comes to my LS3 and cathedral products).
Those applications have a completely different style mounting set-up. ALL of the aftermarket castings come with with flat machined pads and the correct height pedestals provided with the Yella Terra kits (plug and play installation with zero drama).
That said as a distributor of YT products I have still sold dozens of the kits I shipped to Mike (meant for the OEM castings) and I have never had a customer get back to me with fitment issues.
I have an email in to the company who is located in Australia and can update this thread at some point with any feedback I get back from them.
If were me in an effort to get the build going faster I would probably clearance the pedestals of the head carefully (or the inner portion of the rocker) but I understand how most folks wouldn't want to do either.
There is no magic bullet cure.....we would need a set of rockers that are a touch wider between the lower straps of the rocker body that rides on the trunnion.
Mike if you can hit me back with the width of the rocker body making contact with the casting it would be helpful info to share with the YT Engineering team
As I posted in the CF, here are the measurements I have. My calipers read slightly (.002) large when measuring inside slots, diameters, etc. But the differences here are spot on. I was surprised to see the exhaust rocker opening was nearly .015" wider than the intake. Perhaps due to higher exhaust valve temps? .....
Have both heads clearanced for the YTs. Odd bank yesterday, even today. Wasn't really super hard to do, just time consuming. Main concern was/is aluminum powder contaminants into engine. Did everything I could from oiling the castings, covering everything with paper towels and oiling them, with shop vac running. I think I'm good. Have zero lash figured, and ordering PRs soon....
Brings me back to the T&D LS7 Billet Steel roller rocker arms. Those are a true bolt on that's steel and equal to if not lighter than the stock rocker arms. You should be able to clearance those areas by shoving some oiled up shop towles around the work area and take it one at a time. I had to clearance the corners of my Brodix heads for the T&D rocker arms with the heads on and in a 4th Gen Fbody so this should be a breeze. Grinder needs to get to grinding..
These don't fit worth a f%#@, just saying. Pedestals needed clearancing all over, and also needed grinding on the valve cover rail. They perform awesome though! Luckily I was building the engine fresh on the engine stand and not in the car.
Some also claim the roller tip bearing wears out extremely fast, but I'm gambling with it and will wait to see what happens.
Could you weigh an intake and exhaust rocker arm for us? Would like to know the overall weight and the weight over the valve.
You have to weigh them removed from the trunnion to do this properly as the bulk of their weight is the trunnion (which is fixed non rotational mass)
The rocker bodies are definitely lighter than OEM rockers (with their trunnion removed also) and getting a proper nose weight you have to have the centerline of the trunnion relative to how high it sits on the head etc. to get right. Not as simple to measure as the rocker weight
Bottom line Google any Mamo build in the last 20 years....most of you know my stuff always performs and most of you paying attention also know I only use YT Ultralite rockers on all my builds whether they are LS1, LS3 or LS7....I have close to a thousand sets out in the field starting from 2004 (recently inquired to get the total)
If you pay attention to all the details (valve weight, cam lobe intensity, seat and open pressure) these things work flawlessly and don't sideload the valves and the valve guides like the OEM rockers do.
You extend the service life of the head dramatically with this simple and reasonably cost effective upgrade
The fact Mike's rockers didnt clear the castings was a bummer but as I previously mentioned I have never had a customer reach back out to me with fitment issues with this particular part number (Mike hasn't been my luckiest customer that's for sure!)
Looking forward to him finally getting his build running....we are getting close!!
These don't fit worth a f%#@, just saying. Pedestals needed clearancing all over, and also needed grinding on the valve cover rail. They perform awesome though! Luckily I was building the engine fresh on the engine stand and not in the car.
Some also claim the roller tip bearing wears out extremely fast, but I'm gambling with it and will wait to see what happens.
Please elaborate on which rocker you're saying doesn't fit worth a...... , T&D, or YT? If it's the T&D, IDK about them. If its the YTs, they may not fit a very small, minute % of LS7 heads, but even on mine, there wasnt a lot of work involved. I did the first 4 pedestals with a file. Some guys may think this weakens the pedestals. I disagree. Were talking maybe .030" per side, in an area approximately 1/2" wide, and then on maybe a 5° angle, with most of the .030", if it's even that, removed higher on the pedestal, than lower. Even where it is clearanced, pedestal is still thicker than the factory machined thickness on each side of the pedestals. The only pedestals I have personally seen that failed were at the very bottom of the pedestal, where it meets the rest of the casting. Yes-It sucks that the heads were mounted, but that's on me for overlooking the clear warning. From what I've read here and other online forums, my heads are the rare exception. If I had to do any of this all over again, I wouldn't change a thing....EXCEPT checking fitment first, which I almost always do, but didn't this time. AFA I'm concerned, you can't go wrong with Tony. He's been the most understanding and communicative business owner I've ever experienced.....
Please elaborate on which rocker you're saying doesn't fit worth a...... , T&D, or YT? If it's the T&D, IDK about them. If its the YTs, they may not fit a very small % of LS7 heads, but even on mine, there wasnt a lot of work involved. I did the first 4 pedestals with a file. It sucks that heads were mounted, but thats on me for overlooking the clear warning. From what I've read here and other online forums, my heads are the rare exception. If I had to do any of this all over again, I wouldn't change a thing....EXCEPT checking fitment first, which I almost always do, but didnt this time. AFA I'm concerned, you can't go wrong with Tony. He's been the most understanding and communicative business owner I've ever experienced.....
08-31-2024, 07:36 PM
YT rocker Interference with LS7 head pedestals.. 
See the attached pic. I still believe a bolt on should be a bolt on, but they do show the warning.....
To be clear, this is not entirely YTs fault. GMs inconsistencies on the LS7 heads seem endless. But one website, CNC Motorsports, stated that GM used 2 different foundries to cast these heads, and stated some interference issues have been found on occasion. They also stated that the boxes the YT's come in have special instructions addressing this issue. Mine did not, (YES, they DID! See pic above in post #4) and they came directly from Tony from YT in a never opened box......
