Pulled the heads today, I checked the preload and measured out to .08 which seems to be on the higher side. As I thought 2 of the lifters ended up failing.

The plunger was stuck on this one and the clip seemed to have came out of the grove somehow.




This is the one I could put my finger between the retainer and rocker arm:




The machine shop I deal with said I should switch over to some good racing oil like Torco 20-50, going to try reducing the preload as well. How much should I be shooting for? .03ish?

 

The preload is not the problem...The problem is the wrong lifter for the type of application. .080 is fine for a LS7, .030 is not nearly enough. If you wan to run a drop in lifter, then go with at least a Morel 5315 or Johnson 2110.

 

Spot on. LS7 lifters run great between 050 and 100 preload.

 

The thing with the internet is that one guy says it and a thousand others repeat what he said without actually having tried it in real life.

How many people have and have had your typical 0.080 wall 5/16 pushrods in their heads/cam lsx's turning 7200-7300 rpms and doing 11, 10 even 9 sec 1/4 miles.... LOTS and without issues

Along come chinese? or just inferior made lifters and all of a sudden it's the 5/16" pushrods fault so let's shove some broom sticks in there which im not doubting may be superior in bending fatigue but im a believer in everything having a bit of 'flex' with these LS engines results in everything working in harmony without breaking parts. Run mega strong pushrods then your stock rocker arms are more going to want to snap in half at 7000+ rpms.... so then get a set of T&D rockers better suited to your solid 3/8 pushrods and now spring rate could do with being a little heavier so we'll run some titanium valves instead.... until you reach Nascar specs and your wallet is empty... and you'll be lucky if you are any quicker or faster than the guy that stuck with the 'flexible' 5/16 pushrods because your fancy 'air pump' isn't pumping any more air than the next guys basic air pump... infact his heads could flow better and his camshaft profile is better and his combination works as a package even with weaker parts and he goes faster

The 'internet' said LOTS of **** these days because snake oil salesman are hungry and what better way to feed than to create new problems that don't really exist

I'll run a 3/8 pushrod in an 8000 rpm solid roller T&D rocker engine, of course I will. Are they needed in your typical hydraulic roller LS head/cam setup? I haven't seen a 'need' for them. If you think you will get down the track quicker or more reliably with a 3/8 pushrod then by all means do so. Everyone can build their car how they like