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Not shooting anyone. Just stating facts backed up by data. Quite a few builds on here run them without issue, but most are street builds. I’ll be the first to say that if my build were a dedicated track car living at 7k+ rpm, I would go with a Jesel Mohawk setup. But for a street build...which 99% of us on here are, the YT’s work great and live. My limiter is set at 7800 and I’ve been there a lot with no indication of valve float. Again, not arguing with you at all. I stated that the YT’s are indeed heavier, but at 11 grams, it’s easy to overcome.
I hate to burst your bubble but 11 grams is quite a bit heavier over the nose weight, and if you are running titanium intake valves as most of us do, that's definitely a no no
well I'm changing mine out as I'm going with Mast Black Label ls7 heads but LME and come with crower shaft mount 1.8rockers.
Good call. When i got my Mast Black Labels i was working with LME on the same setup but i didn't want to wait that long. I got mine much faster from Mast. I figured if i need to redo it down the road i can send them anywhere later to be reconfigured. The lead time either way was already brutal. Did you go the 305 or the 285 route?
Multiple posts on the Vette forum about all the issues over the years. Just do a search and you'll be quickly awarded with evidence to back it up. Most builders will not say a word because they don't have a dog in the fight. You will see they silently will use stock upgraded OE or Jesel and Crower.
Good call. When i got my Mast Black Labels i was working with LME on the same setup but i didn't want to wait that long. I got mine much faster from Mast. I figured if i need to redo it down the road i can send them anywhere later to be reconfigured. The lead time either way was already brutal. Did you go the 305 or the 285 route?
these are 290cc ports. Done for Madman racing on a blower car.i bought them from him and with 60cc chamber I needed for compression
Ok ok google search then. Sorry if sometimes they take you back there. You do have to remember that the LS7 heads are kinda from the Corvette platform lol!
these are 290cc ports. Done for Madman racing on a blower car.i bought them from him and with 60cc chamber I needed for compression
I wish i could have known Darren Morgan would take over Mast development back then. I couldn't even imagine the advancements that will come about with him on board. There's that lookin up a dead horses *** thing.....grrr
TSP rockers seem to have the same issue as well. My tuner installed a set on his personal LS7 vette. Power flatlined right after 6000rpms where it used to pull till over 6600rpm. Put the stock rockers back in and regained his high peak and hp.
TSP rockers seem to have the same issue as well. My tuner installed a set on his personal LS7 vette. Power flatlined right after 6000rpms where it used to pull till over 6600rpm. Put the stock rockers back in and regained his high peak and hp.
Damn i was waiting and expecting good things from those things
these are 290cc ports. Done for Madman racing on a blower car.i bought them from him and with 60cc chamber I needed for compression
They are some huge ports. Be interesting to see the results, i hope they work well for you.
Darth, on the rockers.. nascar use T&D steel for endurance racing.
Not to show off but rather to try help, these are my T&D's and if you can swing these i think they're about the best you can buy and the last set of rockers you would ever need to buy.
They are some huge ports. Be interesting to see the results, i hope they work well for you.
Darth, on the rockers.. nascar use T&D steel for endurance racing.
Not to show off but rather to try help, these are my T&D's and if you can swing these i think they're about the best you can buy and the last set of rockers you would ever need to buy.
Thanks. I hope it will be when i get it done. Unlike many of you guys in here, i need some more motivation to get off my *** and finish it after years of collecting parts, which is part of my reason for posting this also. This year was going to be the time i get it done, but this covid just threw another spanner in the works and has began affecting me now.
I would love to go straight to a bigger CI aluminum short block to go with these heads, but for now i have this stock stroke 6.0 LS2 to put them on, and i'm just going to turn it as high at the 0411 pcm will allow. I just haven't convinced myself yet to put a 4" stroke in it, i just think it's not needed for some reason especially as i have already bought a 5500+rpm 8" converter to go in the car.
A set of unicorn lentz nascar rods i bought arrived just recently and are in perfect shape, they are standard sbc rod journal size and width, whereas most of the lentz rods are honda journal size, so my next purchase now needs to be the correct pistons, measure for pushrods and then purchase a CID 4.0 intake. These heads are only 235cc intake ports and have titanium intake and exhaust valves, they are small bore LS7's from nascar 24hr daytona, i have no idea what the heads flow, i'm just going to run them and see what happens. An information PDF i have on the engines that ran these heads, it says that the intake valves are canted 5 degrees towards the center of the bores, so i don't know what that affect that will have.. hopefully piston/valve with off shelf pistons isn't a problem as i'm not running a huge cam. And being 12 degree heads they should have a lot of p.v clearance already.
What i still can't decide is if i should run over 13:1 CR and e85 only, or keep it under 12:1 cr and pump unleaded for convenience. The current cam i already have for this build is a comp hydraulic roller, LSL and LXL lobes, only a 243/250 .661 .652 108 lsa, and i think i willl keep it hydraulic roller for now so it won't be anything too spectacular. Maybe i will go to a bigger solid roller later on. Cam specs: ( i didn't choose this myself, i bought it off a guy with a n/a ls3 that was making over 500rwhp before he sold it to go turbo, but he had standard 1.7 rockers, mine are 1.8 ratio. I'm thinking i'll just run it and see what it can do then i can upgrade if i think it's not good enough)
It's been proven time and again that the Yellow Terra's are heavy over the nose and seem to just roll over up top. I know plenty of top name builders that will not touch them with a 10 foot pole. You just can't go wrong with the upgraded stockers to .660 lift.
Sounds to me they were not set up right. These can rev out quite high as long as the open pressures don't exceed the max capability of the rocker.
It also depends on how the valvetrain is set up too.
Power falling off is usually an indication of something not right in the valvetrain.
The stockers even with the trunions do not work as well as a roller tip.
I had these in my LS3 headed engine for nearly 10 years and never had an issue.
I sold them last year and are still going strong.
There is no way I would run a stock rocker with .660 lift.
It's just not wise.
Launch, that is a nice setup! I agree with you on the stroke. Keep it 3.622. I personally have always preferred to keep a motor over square. If you put a 4 in stroke in there you will make the same power but with 30-40 more torque. If you do stroke, sleeve it and punch it out to 4150 or so. My opinion. Honestly, I wish Chevy had not stuck with 4.4 bore spacing and had decided to go 4.5. Woulda made the block a half inch longer and wider. But think of the options and what that would have done for the platform.
Your heads sound like C5R heads. They were a really small ls7 style port but still flowed amaze *****. If the top ten fastest NA lost in the racing section is still valid, check out how many are C5R heads. Maybe that will be worth some motorvation?
It is just not in the cards to swap out the rockers. I am too close to getting it running. Plus the springs were chosen with the YT mass included in the equation. So, it is not as simple as swapping out rockers.
@Bortuous, Chevelle posted 11 grams heavier over the top vs stock. It might have been in this thread in the past few days. Not 100% sure. I would be curious to know the over-the-nose weights of some of the other rockers mentioned also. The info might be in the gen3 stickies. I will have to check.
A close friend of mine is a very respected builder. Been in the game for a VERY long time and has specialized in Vettes for over 40 years. Basically the guy putting together a 440 with stuff from Mamo. He sent all Mamo's parts to him to put it together because the shop was closer to him then Tony. When he seen the rockers in the box that he was supposed to use he just shook his head and said "way to heavy over the nose" instantly. He put it together anyway and the customer was disappointed with the power output comparable to most other builds of the same nature. Of course the first thing pointed to was the rockers in which they pulled them and "Whala" instant 25 hp at the wheels. I agree the right combo is key but shouldn't the parts been already spec'd? Just another "story" of evidence so take it for what its worth.
I was thinking back over this ...
Do you know if those who swapped were running the stock 8mm bolt or had upgraded to the 10mm bolt? Because a surprising amount of instability comes from the stiffness or lack there of in the rocker bolt. Also from undertorqued rocker bolts. The 8mm is 25 ftlbs. The 10 is 40. How many do not ask the question and set the 10mm at 25 ftlbs?
Do you know if those who swapped were running the stock 8mm bolt or had upgraded to the 10mm bolt? Because a surprising amount of instability comes from the stiffness or lack there of in the rocker bolt. Also from undertorqued rocker bolts. The 8mm is 25 ftlbs. The 10 is 40. How many do not ask the question and set the 10mm at 25 ftlbs?
Just some random thoughts.
It might be a reason.
However the majority of the time, issues arise because the valvetrain was not set up correctly. Incorrect matching of components etc...
The way Tony has set everything up etc, I would leave it as is. The combo will work very well. It's proven.
Your yella terras will be fine just as they were on Josh B's engine.
His setup was more aggressive than yours with a PAC 1209X spring and was revving out to 7800rpm or so.
He was running the same solid camshaft as me but a 264/276 112 LSA.
Tony has gone over this so many times and clarified everything to the best of his ability.
