Generation IV Internal Engine - LS2 TFS heads trunion ?

I have a 408 LS2 being built with TFS heads. I am running comp limited travel lifters, BTR 0.660 springs and I have the rockers with comp trunion upgrade to put on the heads. My cam is an LSL 239/243 112 0.624 lift.

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.

Any help appreciated!

I run .671 lift on stock LS7 rockers with truinion upgrade with no issues to 7400 rpm. Find an engine guy who knows something about LS motors

The stock rockers are harder on the bronze valve guides. If you like the stock rockers w/ trunnion upgrade and many of us do, have powdered metal valve guides installed in your heads.

The stock rockers are harder on the bronze valve guides. If you like the stock rockers w/ trunnion upgrade and many of us do, have powdered metal valve guides installed in your heads.

Yeah, I forgot to mention I have powdered metal guides

The two factors that limit the reliable use of the oem rockers (not including LS7 rockers, which are different) are open spring pressure and lift. The limits are about 400 pounds of open spring pressure and 0.600 lift. Exceeding either of those parameters introduces the risk of valve tip damage.

http://ls1tech.com/forums/15983303-post14.html

OK, so I read that thread, and I guess Tooley is pretty good...but why do we have stories of folks all over the place running stock rockers with and without trunion upgrade with cams over 0.600 lift, putting thousands upon thousands of miles with no issues. I had 50k miles on an LS2 and 20k on an LS1, stock rockers, no trunion upgrade, 7000rpm redline, 0.620ish lift. There are too many folks doing this to be blind luck.

I am not opposed spending money for safety, I'm just not sold on the idea that its necessary.

OK, so I read that thread, and I guess Tooley is pretty good...but why do we have stories of folks all over the place running stock rockers with and without trunion upgrade with cams over 0.600 lift, putting thousands upon thousands of miles with no issues. I had 50k miles on an LS2 and 20k on an LS1, stock rockers, no trunion upgrade, 7000rpm redline, 0.620ish lift. There are too many folks doing this to be blind luck.

I am not opposed spending money for safety, I'm just not sold on the idea that its necessary.

Obviously the failure rate is not 100%. I believe that open spring pressure contributes more to the issue than lift, particularly moderate lifts that are closer to 0.600 than to 0.650. In any event, folks should be aware of the risks when choosing components.


http://ls1tech.com/forums/generation-iii-internal-engine/1534309-car-running-extremely-rich-very-rough-idle.html
http://ls1tech.com/forums/generation-iii-internal-engine/1523434-broke-rocker.html

If you don't mind spending the money, then TD Machine has shaft mounted roller rockers made for Trick Flow heads. Part # 20047 Trickflow LS1

If you don't mind spending the money, then TD Machine has shaft mounted roller rockers made for Trick Flow heads. Part # 20047 Trickflow LS1

I got a good deal on Yella Terra's adjustable shaft mounts, so I went that route.

I agree that it has more to do with the open spring pressure, I am one of the few that had my valve tips and guides prematurely worn on stock heads running the comp 926 springs with a lsl 235/239 comp cam with only .621 lift on both intake and exhaust running stock rockers with Trunion upgrade.

Im running tsp 408 with ls3 heads and stock rockers with trunion kit making big power with no worries all day.

I got a good deal on Yella Terra's adjustable shaft mounts, so I went that route.

There are basically two ways to set up that valve train, or any other valve train using 15 degree rockers. The 12 degree rockers are a better design and will tolerate more lift.

PM guides, stock rockers, .630" lift or less, less than 400 lb open spring pressure and 5/16" pushrods.

Roller rockers, .650" lift or less, springs with higher open pressure (420-450lbs) to control the heavier roller rockers, and 3/8" pushrods to avoid the "pole vault" effect of 5/16" pushrods when using the higher open pressure springs.

I prefer the stock rocker route with less open spring pressure. Grind the production locating tabs off the rocker rails and DON'T shim them up.

You might consider my Max Pressure springs if you're staying with the roller rockers.