tdrumm

iTrader: (18)

I have the 062, and am toying with the idea of doing their 1.8 rockers when I do the swap, but I have a few questions...

1.) That would put my lift at .583/.583, how well do our heads flow at that amount of lift? Have we reached the point of diminished returns without a head swap?

2.) How much lift can we safely run without having piston to valve clearance problems?

Sport Side

iTrader: (6)

You can throw a larger lift cam in a head that say stalls out @ .55 lift and you'll make power. It's a balancing act... Just like, when you have an efficient set of heads, you can use less duration on the camshaft. The head is doing the work. Or shitty heads need a larger camshaft to flow the same amount of air.

No need to worry about lift & pv clearance. The piston is on down the bore when the valve reaches max lift.

2redgmc

iTrader: (1)

I have those rocker arms on my truck.
the install was a pain in the ***.
I'll give you a tip
Cranes definition of zero lash is when you cannot turn the pushrod.
They don't say that in the instructions. I bet that was not your definition of zero lash.
The shorter pushrods are needed because of the rocker are design. You cannot use the stock pushrod with these rockers.

And you will need a good allen socket to install the studs.

Sport Side

iTrader: (6)

Drum,

Here's a few more words about the quoted subject.

It is true, the LS1 heads do not flow very well over .550 lift. BUT.....the turbulance caused by having the intake valve open more then .550 aids in atomizing the incoming air/fuel & actually helps power. Plus, the higher the lift you have, the more duration you have above .500 valvelift....which is also good.

Typically you do not want to go more then .050 above where the heads start getting turbulant.

marc_w

I got the rockers installed this weekend... It took me quite some time, and I had some problems. I'll get a full writeup on here either tonight or tomorrow sometime.

Preliminary results are nice... but I think I'm being limited by some form of TM (like max axle torque or max tranny torque). My HPTuners-scanned delivered torque is plateauing at ~440ft/lbs. Pre-rockers, I would peak around there. Now, I'm "running into it" for a larger area in the power range.

I wanted to put up these few pictures here.

Passenger side bank.
Driver side bank.
Poor pic of driver side bank - pushrods, studs and guideplates.

mattrem

iTrader: (7)

How does the valve train sound? I hear that they are supposed to be very quiet. Are they as quiet as the stock rockers?
Marc atleast you beat the weather, We are getting pounded in Jersey right now.

marc_w

For the most part, the VT is VERY quiet. I have a little bit of a "piffing" or scissor-like noise when I let off the throttle.. and the VT noise outside the vehicle while it's idling is slightly increased, but it's nice. It doesn't sound sickly or anything - just a little more of that scissor noise.

It's still MUCH quieter from the VT noise I had from the last cam. I drove through our parking garage at work with my windows down, and everything sounded nicely tight.

There is still that rather loud factory "tapping" in the center of the motor when it's idling - I don't know what that is. Injectors firing, or timing chain noise, or the cam's reluctor wheel or something?

I guess I have a few minutes to go over some differences I noticed:

Idle: Idle is "cleaner" and the light cadence of the cam is more pronounced. It sounds as if I got a nice idle-tune done, and free'd up my exhaust some more.

Exhaust volume: Noticeably louder. Mostly noticeable at idle. I'm not sure your girlfriends would notice, so it's not a huge change or anything.

Power range: I currently no longer have that very pronounced 'light off' of the cam in the 1,700-1,800 range. It's all smooth pulling from 1,100rpm up. My midrange seems to really come alive now, quite noticeably around 3,600rpm. It rev's out much better up top - doesn't feel as if it's just a low end / midrange torque cam anymore. It seems more willing to be rung.

I was able to lug up a long/steep hill locked up at 1,100rpm at 36-37mph today - something that I've never been able to do over the last 33K miles I put on the truck. (Something that some people might not care about, but I get a kick out of that stuff).

Overall it's still the same old 047, but more refined down low, and stronger up in the midrange and top-end.

It looks like highway cruise mileage will increase a little... It still sucks it down at any hint of an agressive pedal.

Sport Side

iTrader: (6)

You're real good at those detailed descriptions

Glad you like it.

marc_w

My install:

I initially tried to set the initial 0-lash by setting the rockers tight enough as to not allow the pushrods to easily be rotated. I used a regular ol' wrench to do so. The procedure to set the initial lash is basically:

Set all rockers to 0-lash. Turn over the motor one full revolution. Check again. Turn over one full revolution again, and check again... repeating for 4(?) times.

What was happening is that my lifters were bleeding down in the time it took me to crank my motor over and re-check things. I'm thinking that I'm not getting things tight enough, when in fact I was.

The procedure was then to add a 1/4 turn of preload, and wait 15 minutes. Come back and add another turn - until 8 turns have been completed.

Well, upon my 8th round at things, I got "that feeling". I felt two of the pushrods bottom out on me. The posi-locks were definitely not contacting the stud. I backed the adjusters off a quarter of a turn, and buttoned things up for rocker to valve-cover clearance testing, which seems just fine. I turned over the motor by hand about 10 times before I decided to try to start it. I pretty much knew it wasn't going to start. I only had compression for every 3/4 turn of the crankshaft.

It was a big no-go. It sounded very-very bad. I had maybe one cylinder trying to fire, and I swore it sounded like the started was severely bogged down like my battery was dead. (it wasn't).

I was pretty well convinced some valves were staying cracked open.

I paniced, jumped in the Internal section on the site, and was rescued by mrr23. After a phone call with him, he informed me to just finger-tigten the initial lash, and he told me what to look for when the lifters bled down.

So I pulled things down again, set my initial lash just finger tight (and crank over the motor a few times, checking around each 1/4 turn). Simple. Done.

I went ahead with the 1/4 proceedure. I payed no attention to the pushrods. I felt what the rockers felt like with just finger-tight 0-lash. I snugged them all up with their first 1/4 turn of preload, and immediately felt them again. I noted their "stability" (for a lack of better wording). I hung our for about 5 minutes, and rechecked the rockers a few times. After 5-7 minutes, the lifters all started to loosen up again like they were only finger-tight. This is the sign to go ahead with another 1/4 turn of preload. The rockers didn't get completely sloppy, they just had "that feel" to them.

So after 7, 1/4 turns, it was time to do something different - mrr23 told me to snug down the posi-lock on the last round of 1/4 turns ---- not do the 8th pass and THEN lock things down. I noticed that just snugging the posi-locks themselves, doesn't provide a whole ton of holding power. When you snug the adjuster AND the lock down at the sime time - they become EXTREMELY secure.

I threw everything back together, and the truck basically fired right up. I had a little VT noise for the first few minutes, even a few squeaks/chips (I THOUGHT I prelube things pretty well) - but all of that cleared up shortly.

VHP put up some helpfull information on this on their site this morning.

marc_w

I know - I just type what I'm thinking at the time... which may or may not be all that good.