red shadow

Can i use 1.8 Rockers with 212/218 .558/.563 LSA 115 cam ?
Springs are Comp Cams 918

XTrooper

.590/.595 with the 1.8 rockers. That's definitely doable.

StickSS

Hi: People have used the 02 Z06 cam with 1.85 rockers so I don't see why it can't be done. I am surprissed That no one has ever tried this combo before with the crane dual springs and crane 1.8 rockers. It would Idle good and might be a good sleeper cam?

Bill's 02 Z-28 SS

Hi Folks
the question is what heads and springs are planning on using? The ZO6 head can't use the 1.85 rocker, the max is .571.
Bill

PREDATOR-Z

Yes you can, but better to use Crane 1.72 "variable lift". You'll get the down low benefits without stressing your top rpms.

Spinmonster

???
I used LS6 heads with a bigger application....my net lift with the 1.8's was like .628 or so.

If it is a clearance issue, it will fit but for everyone's liablity it should always be clearance checked. I used an XER 224/230 .581/.592 with 1.8 cranes on a stock bottom end with flycutting for comfort. If the question is about the cams compatability with the rockers....no issue what so ever as long as you use a good dual spring with good seat pressure and lift limits.

Finally if you question is specifically if the 918's are up to the task, I would think its too much for that spring. While I am aware that the spring is rated to .600 and that may seem enough, the issue is that the crane 1.8's weigh exactly 12 grams more than the stockers (152 vs 140 as per my scale) and I would want more spring pressure to control valve float over 6k. If you're using this only on the street and keeping it under 6k which is where your power bands ends anyway--with new springs it is on the line. If you didnt buy them yet get the crane duals, shim them to 1.77 installed height for about 124 lbs seat pressure and put it in. Should pull great down low with great idle even untuned. With a bigger cam I have reved much higher than that. I spoke to Mark Campbell from Crane about my application which is far more agrressive than yours is and he assured me that they had tested high rpm stability with these rockers and those springs and it is a great combo. If you are using Z06 heads with the lighter valves there will be even less of an issue since the hollow stem valves will more than make up for the added rocker weight. I dont know what you already own but my guess is you have the cam, heads, and springs and are looking to add power without a cam change.....it will work and net you 10-15hp but I would change the springs.

PREDATOR-Z

I beg to differ on the 918 issue.

1- They do not need to be shimmed
2- They have plenty seat pressure up to .620 lifts
3- The lighter your valvetrain moving mass, the better. {my total moving (effective) mass (valves, locks, spring and retainer) is 127gr}
BTW these are the weight for the following:
Beehive Spring 72 g (I do not know where you got 140gr from )
TI Retainer 8 g
Steel Keepers 6 g


4- Let us put this to rest once and for all (the 918's were designed for radical XE-R lobes up to .620), it is only after 921 duals came out, that Comp reduced their advertised lifts since they were so close to the 921's.(marketing necessity)
5- I ran the 918's on 610 lift cams to 7000 rpm with no float (but proper preload is necessary), which means proper p-rod length with non adjustable rockers (p-rod meter used and custom ordered)

Spinmonster

Jesus, it seems everytime I post something you take it as an attack....If you re-read what you quoted me on you will see that I suggested the crane duals be shimmed thank you very much...that whole post because you thought I attacked the precious 918's.

I revved the crane 1.8's to 7100 with no float with my duals and it put down 441rwhp with no fall off....so much for high speed instability so I guess they're both good? Can you at least live with that?

~JOSHUA

iTrader: (92)

If you're using stock heads I don't see the point in lifting valves to high heaven and hammering 'em If you don't have stage 2 heads to take advantage of the lift.

Bill's 02 Z-28 SS

Hi Predator-Z
The Max lift for the ZO6 heads/valve springs is .571 per GM. The 1.72 variable rocker just pushes past that limits. I know you push the limits on anything but it is not going to last very long.
Bill

Viper

iTrader: (6)

Bill

Is it possible that GM quote is only based on using the stock GM springs?

I'm assuming at this point the guy will swap springs.

PREDATOR-Z

No attack, but I'm tired of the false belief that is continuously repeated that 918's can't handle anything, close to .600/ They will go way beyond that at proper install specs, with correct preload on the lifters.

My answer was for the 918's but since you mention it, Crane 1.72 will have no effect on max lift of that cam or any cam if used (well, .02 extra).
Unlike stock rockers which start opening the valve at 1.52 ratio, these Crane 1.72 will start at 1.79, then by .200/.300 drop back down to 1.72 till max lift, therefore not really affecting those max lifts.
So they will have no ill effect on stock springs.

red shadow

This setup will be a Z06 , so if i changed the springs to crane dual + crane 1.8 rockers , will it work ?

PREDATOR-Z

|If you allready have the 918's, no need to change the springs. Otherwise, yeah Crane duals will work.

smask04C5

iTrader: (1)

yes they will work fine

Bill's 02 Z-28 SS

Hi Viper
You are 100% correct, that was assuming stock springs and I was only quoting GM for their GMPP LS6 heads. If changes out the spring or has different spring installed, he go to the limits.
Bill

Spinmonster

It will work well.