Is the stock rocker with trunion upgrade adequate, or is their a real concern necessitating I run a full roller?

My engine guy says anything over .600 lift and 6000rpm needs full roller (he is a Ford guy). He also is concerned about spring pressures. Additionally he suggests that once preload is set with pushrod length if the valves need to be adjusted in a different spot it would be nearly impossible with the limited travel lifters. He says with aluminum block/heads preload changes a lot when it gets hot.

I have too much money in the setup as is, and really don't want to have to buy yet another set of rockers. The motor will be used for HPDE, autox, and some daily driving.

Anyone know the documented limits on rpm, lift and pressures these stock rockers with upgrade can withstand?

Any help appreciated!

 

The problem that occured that made TF state you need roller tip rockers with their heads was that the valve stem tips wore causing big damage. Rocker arms dont push straight down on the valve and roller tips reduce lateral pressure on the stems which occurs at all but one position in the range a rocker arm swings.

Using non-roller tip rockers will void the warranty on valve tip wear.

The difference in cost between yella-terra and trunion upgrades is about 300 bucks, it comes down to your comfort level in lying to get a repair when it fails. I would get the roller tip rockers because I wont/can't lie.

 

LOL, what does lying have to do with choosing a rocker arm. These aren't TFS bought from TFS, they are Advanced Induction's custom CNC TFS castings. They don't have a problem with me running stockers as long as I ran the PM guides, which I am doing.

My question is in reference to what the capabilities of trunion upgraded stock rockers...how much lift, rpm, seat pressure are they capable of running? Right now my understanding is low 0.600's lift (my cam is 0.624), and spring pressures less than 420lbs.

While I do plan to upgrade to T&D or Jesel in time, right now, I just want to get an understanding if I am safe to run the stockers.

Thanks

 

Your first post said nothing about advanced induction porting/build so anyone reading it may have assumed you simply had TF heads and TF's warranty. The question I was answering for you was this one that you asked:

As TF's use a different valve angle, I posted that I felt you should use the full roller on TF's head. Advanced induction having ported them and built them in my opinion doesnt change the fact that the valve angle is different than stock. Had you indicated in your first post that AI is ok with non-roller tips, I wouldnt have mentioned TFs warranty but I still wouldnt use a non-roller tip on a 13.5 degree head.

To answer your second question in the first post and the one above highlighted in red (what they can handle):

As a supporting tuner on this board for years, and having done countless head swaps with various rockers, I've used stock rockers on 800rwhp builds to 7100rpm with .614 lift on XFI lobes and 425lbs open pressure on springs so you should be fine with the trunion upgraded stock rockers if the heads/valves are ok with it...ie the modded rockers will handle it since the stock ones do. In fact, I've never personally had a stock rocker fail on any build. My car had the stock unmodded rockers for 959rwhp for three years, then I sold the car. I only revved to 6800-6900rpm though.

Now ignoring the fact these are TF castings, your ford engine guy is mistaken about the generalization with the stock rocker. Almost no one gets different rockers for head/cam swaps on this board. Just about every cam is over .600 lift with many as high as .646 lift using the bone stock rocker with as much as 450lbs open spring pressure. I have yet to see a dyno sheet of a cammed car stopped under 6600rpm with most going to 6800 with stock rockers. The reason to get the trunion replaced is to avoid the very rare event that the needle bearings get dumped. I've dyno'ed over 100 cars to 6800rpms with stock rockers. I'd bet most tuners who do this full time can say they've dyno over 1000 to that rpm with stock rockers.

I hope these are usefull data points.

Good luck with your build.

 

I agree totally, and am really having a time getting everything done. Such a decrepancy between LS and Ford / SBC etc is creating somewhat of a hardship between our thought processes...I am recommending things that we are all familiar with, and he disagrees and wants to go a different direction. Since I will be doing some road racing, running many laps at high rpm at a time, I got a good deal on some Yella Terra Adjustable shaftmounts, so I went that route and will offset the cost by selling my stock upgraded rockers. It sure wasn't my idea, but I'm trying to leave this build calling him a friend.

I have had 2 motors with stock rockers (not even upgraded) that were on cams with up to 0.620 lift, 1 an LS2 I put 50K miles on, the LS1 I put 20K miles on, both made over 500fwhp, and I never had issues with either otor in terms of rockers or valvetrain stability.

Im trying to put good parts in the build, so hopefully it all comes together well....if I can make 500rwhp I'll be happy.

 

In this application, I would use a full roller. The Yella Terra Rockers are good to around 400 lbs and that is it. I have seen them break in applications where the spring pressure was to high and the valve train was stressed. With the TFS Heads, the valve guide will wear with the stock rockers..... bronze versus powdered metal. The stock rockers can stab the valve and provides uneven wear on the valve and valve guide.

With that said, most aftermarket rockers are bigger and a tad heavier. The valve cover will need clearanced or use thicker valve cover gaskets.

 

These aren't the Yella Terra Ultralights, these are the Platinum Series Race Rocker, these are good to 1000lb open pressure and 0.750 lift, they very close to the Jesel or T&D, but without the true adjustability they offer.

 

The top of the TF head where the valve cover seals is .200 taller than a 243 stock casting, I run the larger UL non adjustable YT rollers with a stock valve cover gasket without clearance issues.

Good luck with your build.