11 Bravo

iTrader: (3)

Just something I'm pondering. I believe the specs for my '99 are: 202/210 .496/496 116. If I added 1.8 rockers, what would that change the #'s to? I know, you'll say for that price it's not worth it. A certain place has the Crane rocker kit (w/ pushrods, guide plates, hardened studs) for $649. Seeing how I would not have to pay someone to do it (unlike a cam install) it may not be a bad deal if it would bring the specs up to a LS6 cam or higher. Actually, it would be a very good deal. Can someone figure it out?

Reckless

iTrader: (9)

It will only affect the lift.

Stock lift - .498 divided by 1.7 = .2929
Change ratio to 1.8 - .2929 x 1.8 = .527 lift

Your new lift would be .527. Not worth the money IMO. You can get a more aggressive cam for the money and use stock rockers and be ahead of the game if you change the cam yourself.

Ooops! Goofed up the initial number, but you get the idea.

[ December 26, 2001: Message edited by: Reckless ]</p>

11 Bravo

iTrader: (3)

Depending on how you look at it, it may not be a bad deal. Many people cannot do a cam change themselves. Most could install rockers, I'm sure. If 1.8 rockers put the lift at .527, then that would be right at '01 LS6 cam specs, with slightly less duration. The money you would save on a cam install would kinda equal things out. And you could easily put the factory rockers back on for a trip to the dealer. I'm not going to do it, looking for a little more power than that, just something to think about on a slow day <img src="gr_stretch.gif" border="0">

Terry Burger

iTrader: (4)

You have to swap valve springs either way, which is the majority of the work. Just do a cam swap.

Pro Stock John

iTrader: (34)

We already have 1.7's stock.

This mod works better on older F-Bodies.

SilverGhost

iTrader: (53)

Not worth it. Stock rockers already have a rolled fulcrum..just not rolled tip, which is only advantage cranes offer(correct me if i'm wrong people)

whoever said you gotta change springs and **** anyway when doing cam is right..makes sense to just do the cam as long as you're replacing springs and pushrods and what have you.

although in my opinion doing that is the easy part..changing the cam is the pain in *** to me.

Jackyl_30

[quote]Originally posted by 11 Bravo:
<strong>Just something I'm pondering. I believe the specs for my '99 are: 202/210 .496/496 116. If I added 1.8 rockers, what would that change the #'s to? I know, you'll say for that price it's not worth it. A certain place has the Crane rocker kit (w/ pushrods, guide plates, hardened studs) for $649. Seeing how I would not have to pay someone to do it (unlike a cam install) it may not be a bad deal if it would bring the specs up to a LS6 cam or higher. Actually, it would be a very good deal. Can someone figure it out?</strong><hr></blockquote>

Just so you know. I have ordered that kit and they are back ordered. I ordered them from Thunder Racing. Also Tbyrne is back ordered too.

Trevor @ Texas Speed & Perf.

iTrader: (3)

Keep in mind that you don't just slap the rockers on and torque them down to 22 lb./ft. like you do the stock shaft-mounted rockers; the Cranes are adjustable. You do have to set lifter preload. I set them at 1/2 turn past 0 lash on my '98 T/A.
I'd definitely reconsider getting the rockers. When you have an airflow restriction (i.e. stock heads), added duration will help more than lift will. Your $649 will be better spent elsewhere. I was running .599" lift on a 383 with the rockers; I only changed them because I didn't want to end up with some needle bearings floating around in the engine after all of the money was spent. In the long haul, 6,800 RPM shift points and that kind of lift will take its toll on the stock rockers.

Plan B

I tried this with the stock set-up! (just bolt ons) I had the car dyno'd in the morning, installed them and dyno'd the next morning. I lost around 10 rwhp and a fair amount of torque.

Just a little experiment I tried, whilst waiting for my Heads and Cam combo to be completed.

I then ran a back to back comparison on Comp Cam 216/220, 114 lsa. The 1.8's, with the head work, produced more power at this stage. (not a lot, but more) I now have a custom grind Comp Cam 224/224, 112 with a total valve lift of .570 using these 1.8's. Hope this helps.



Look ma! no steering shaft. <img src="gr_grin.gif" border="0">

[ December 27, 2001: Message edited by: Plan B ]</p>

jmX

[quote]Originally posted by Plan B:
<strong>Look ma! no steering shaft. <img src="gr_grin.gif" border="0">
</strong><hr></blockquote>

LOL, you backwards folk are funny <img src="gr_stretch.gif" border="0">

gwj

Good Lord, look at all the easy access in that engine bay! <img src="gr_grin.gif" border="0">

Fran D

iTrader: (5)

[quote]Originally posted by Reckless:
<strong>...It will only affect the lift.</strong><hr></blockquote>

That's not strictly correct.

Since the numbers he quoted look like the duration at .050" lift, the subsequent opening at .050" would be earlier and the closing at .050" later with the 1.8s.

However, without knowing the real cam profile, it's very difficult to determine what the increase in duration may be. More to your point, it could be miniscule (does anyone have the 360 degree profile?).

My experience with a little more aggressive profile and a larger ratio change (1.5 to 1.7) yielded duration increases of 3-4 degrees at .050".

LS1powerN20

they sure do look pretty though <img src="gr_images/icons/cool.gif" border="0">