qwikz28

iTrader: (12)

Hello guys-

I was trying to measure the necessary pushrod length in my car this weekend and am more confused than when I started. Using the Comp pushrod length checker, I started at 8 full turns and moved up half turn waiting for the rocker to not be able to move. At zero lash, I came up with 10.5 turns when the rocker was unable to move, which equates to 7.325". Now, considering preload on my LS7 lifters, how long pushrod should I purchase? Am I correct in saying 7.400 with .08" preload? What is the margin for error with these things?

Thanks

Jacob

salemetro

iTrader: (5)

Considering your measurements....7.4 will get you .075 preload. Some say to run .050 (7.375), while others say .020(7.345). In my experience with these lifters, I don't know what to say. Except....read this :

https://ls1tech.com/forums/generatio...lve-train.html

My own person tribulations with these lifters. Take it all with a grain of salt.....then hope for the best.

Hope this helps.

-James-

baxsom

iTrader: (6)

interested in this one as well because i have read over and over again on this and corvetteforum.com to run .080 on the LS7 lifter but can be ran as deep as .100 to combat noise. There is also a lot of builders here saying that you need a shorter pushrod with the ls7 lifters as well which kinda goes totally against the other arguments.

01ssreda4

iTrader: (96)

I always get 1 3/4 turns from zero lash and my engines have always been silent. Double check a few lifters just to make sure. Don't make your pushrod purchase off one measurement.

ZeeOSix

This chart is supposedly what these specific lifters should be pre-loaded to. Do you know the GM part number of the lifters you have?

salemetro

iTrader: (5)

[QUOTE=baxsom;15906305]interested in this one as well because i have read over and over again on this and corvetteforum.com to run .080 on the LS7 lifter but can be ran as deep as .100 to combat noise. There is also a lot of builders here saying that you need a shorter pushrod with the ls7 lifters as well which kinda goes totally against the other arguments.[

Keep looking/ reading....it gets pretty bizarre. I'm convinced that there are 2 different stles of ls7 lifters.

salemetro

iTrader: (5)

Good advice ....but didn't work in my case.

ZeeOSix

According to the chart in Post #5 above, the 2006 LS7 used a different lifter than the 2007+. Not sure what you get these days from the dealer if you go ask for an LS1, LS6 or LS7 lifter.

vettenuts

iTrader: (4)

You could try an experiment if you have the stock pushrods. The stock pushrods are 7.385" gauge length (they are not 7.400"). That would give you 0.060" preload. Put them in and try them to see how quiet they are. That will give you a no cost evaluation and you can decide from there. I wouldn't go racing with the stockers but just run the motor easy to test for sound.

qwikz28

iTrader: (12)

The pushrods that were in the car are 7.400 but one bent when I broke a rocker and I went back to OEM rockers.

I measured the same one twice and got 7.325" on the length checker both times, but I didn't think to check a different lifter. In the end though, I still don't know how much preload to run. The 1 3/4 turns that 01redss mentioned would equate to how much preload? That would be necessary to determine pushrod length, would it not? I suppose I could also try the 7.4s I had to see what kind of wipe that gives me on the tip of the valve with the sharpie method.

Thanks for your help guys.

camaro98rs

iTrader: (2)

I set my new ls7 lifters up with a preload of. 050 and they are nice and quiet.

baxsom

iTrader: (6)

the ls7 lifter is the standard.

the part numbers are different in that it says that the lifter and tray is one part number while just the lifter is the other. you cant buy ls1 or ls6 lifters anymore. if you look up their part number they have been superceded by the ls7 one.

Havoc40

You have to be careful deep setting these lifters, creating a cheap short travel, and screaming them to the moon. These parts were not designed for that. If you set your preload too deep, you run the risk of over pumping the lifter during valve float. Depending on your combination, this can cause you to hang a valve in the cylinder and maybe smack a piston. A couple things have to happen exactly for this to occur, but it's still a risk, and it has happened before.

If your conscious about what's actually going on and not screaming this thing past 6.5k regularly, there is no harm setting them up past .050". Just be aware of what your doing, and what effect you might have. There's a reason a properly built short travel has a spacer in it.

baxsom

iTrader: (6)

is that why everyone is saying that .080 is the standard?

Havoc40

That statement was for general knowledge of what can happen, and what exactly you risk.

I really don't care what everyone, meaning the internet experts, have to say about this topic. When you run the piston into a lifter .080" or .100" that has .200" total travel, you run the risk mentioned above. That's fact.

Doesn't mean that the engines I've built using these lifters, I ran .030 or .050 preload. Typically I've found .065-.080 to quiet these things down, but I'm also fully aware of what can happen and the story of why it takes that much preload to accomplish a quiet valvetrain on some parts. Some will work just fine around .030-.050 preload, what the "standard" really is for most hydraulic lifters.

ETA: Typically the parts that are bleeding down faster, causing the noise, won't over pump. The big issue is when you run a part that has more internal resistance, with that much preload.

qwikz28

iTrader: (12)

I don't really see why people care so much to quiet down the valvetrain, and then put a cam and full exhaust on the car. It's not a Cadillac.

Havoc- Thanks for the info. If .03-.05 is what you recommend, then I'm realistically looking at a 7.375 pushrod if my first measurement was accurate. I'm going to double check my measurements this weekend on other lifters like someone had suggested earlier.

Thanks again guys. It's amazing just how precise you have to be with these engines.

salemetro

iTrader: (5)

It's not just a matter of noise....it's also a matter of obtaining the most valve lift. Noise means (as I understand it) that your lifters are bottoming out, which means that valve lift is suffering. Personally, I want to know that the cam is able to do it's job just as it was intended.

Havoc40

Took the words right out of my mouth salemetro lol.

I should add to that though...if the parts are falling right in spec and the rest of the components (springs, retainers, etc.) don't overcome the hydraulics of the lifter, it can make noise and still pump up (netting full lift) once you achieve max oil pressure. But I'll be willing to bet a dyno pull says your leaving some power on the table. How much is always the question guys like me are looking for answers to...I've seen as much as 30hp in worst cases.

sepsis

iTrader: (7)

True, it's not a caddy, but why should we have to put up with excessive ticking and clacking when we can do something about it?

01ssreda4

iTrader: (96)

On an average car, less then dyno variance % from run to run, so you're arguing a moot point IMO.