The turbo build on my 5.3 is coming along quite well (I'll have to start a build thread with pics sometime) but I have reached a point where if I am gonna to internal modifications nows the time.

My concern is the stock valve train. I know ideally I would buy a new cam(vette cam?) new pushrods and springs, but honestly I don't feel like spending the money/time/effort right now, maybe in the future

So my dilemma is valve float. I have heard stock springs will suffer from valve float on boosted engines, and the last thing I want is a junk engine from broken valve. With 3.0 rear gears and an auto trans the car spends most of the time between 1500-4000rpm, and the wastegate will be set at ~7psi to start.

So should I at least upgrade the springs? If yes will I need new pushrods/retainers/locks?

Any suggestions on springs/pushrods? I know summit sells GM LS6 replacement springs

Any help would be great

Thanks, Matt

 

You should be fine to 10 psi if not alittle more, I only changed out my springs and PR's because i was already in there swapping cam. Also stock length PR's will work on a Ls6 cam.

 

at 7 lbs i would say your alright..

but my 5.3 in my trans am would float the valves with 10 lbs... once the engine was boosted on a few times and warmed up real good.... they floated pretty much instantly at 4800-5000 wit 16#'s... but you have that (and shouldn't run 16#s on a stock 5.3 and 91 anyways... haha)

 

I've got Comp springs... They were there before the turbo, but either way I'd have done them for boost... Also running 6-7psi

 

I'd get them done, spending a few hundred now will save you from spending more later if you do get some valve floating...I'm running Comp springs

 

At your low rpm and low boost level you should be fine. On the other hand for the cost I'd just put some LS6 springs in there since you already have the engine out. That would help ensure no issue's under mild boost.

 

mine floated at 10psi. so i spent $50 and got some new ls6 yellow springs.

 

Theres a train of thought out there that on any boosted motor the incoming PSI will help lead to valve float earlier the a NA motor. So one would run higher spring pressures then what would be considered for a NA motor.

So I would look and see what others on the board have done, and even give comp cams a call. I ran Beehives on a 7500 rpm motor I built, and there quality is excellent. There also supposed to be lighter then normal springs, and also check into tool steel or titanium rings and keepers. They will help lighten up the load to keep spring pressures lower to help longevity of the cam, and lifters.

Also Large valves on a boosted motor give more surface area for the air to try to hold open the valves thus inducing valve float earlier.

 

Thanks for the replies guys, I think for right now I am gonna try and finish up the turbo build and work the bugs out of it, still have to upgrade injectors I figure.

I think I will change out the springs (maybe cam too) in the spring once I know the turbo stuff is operational

thanks again