The Vigg

iTrader: (3)

Hey Folks,

Need some guidance from the experts. I was wondering if the stock ls6 springs were sufficient for Crane 1.8 quick lift rockers. This is on a Cadillac CTS-V, so please no comments on I should have gone for cam. If concensus is springs, would 918's do, or is dual spring required? What dual spring kit will fit stock heads without machining and work well? Any guess as to real world gains with 1.8's (other mods headers, intake,exhaust )

Thanks

Tainted

iTrader: (9)

ok do this, its an equation for finding your new lift by increasing the rocker ratio

as an example we will use my cam since I dont know your specs

228R 228/228 .588/.588 112lsa stock 1.7 rocker

so what we are gonna do is take 588(intake and exhaust lift) and devide it by 1.7
588/1.7 = 345.8823529411764058823529411765

now we take that number and multiply it by your new rocker ratio to get your lift
345.8823529411764058823529411765 x 1.8 = 622


so by using a stock 1.7 rocker im at 588 lift and using a 1.8 rocker im up to 622

understand?

The Vigg

iTrader: (3)

Stock Cam specs are:

204/218 int/exh @ 0.05" duration
0.551" / 0.547" int/exh lift
117 LSA

So that said I would be at total lift of .583. I guess the overall question I have is whether LS6 springs would sufficient to control valve float.

Tainted

iTrader: (9)

583I 579E

I think LS6 springs are good to like .565 or something, look it up to be sure.

you really gotta watch rockers though, if you ever do a cam some dont reccomend you use such a high lift rocker

vettenuts

iTrader: (4)

The stock springs won't keep up with the acceleration rates of those rockers. I would get the PAC 1218's or better yet the PAC 1518's, which will run a lot longer mileage wise. These rockers come off the seat at a high rate, you will need new springs. I don't trust the Comp 918's only because there still may be a few sets of the bad ones floating around out there and PAC's stuff is excellent (they used to make the Comp 918's).

Weezzer

How about the 921's?
I know they are made for higher lift, and they are heavier - but won't they last longer and not wear out as quick because with a light lift of .583 max your operational parameters lie well under the max lift that spring is capable of.

vettenuts

iTrader: (4)

Total overkill in my opinion, especially when loading up the stock timing chain.

The Vigg

iTrader: (3)

How can I tell which 918's are bad? With the lift and ramp rates I would have do you think 918's would last relatively long? Do those PAC prings work with stock retainers and locks or do I need to upgrade

vettenuts

iTrader: (4)

Comp used to have PAC make the 918's for them, then they switched manufacturers and ran into problems. If you go straight to PAC (there are a couple of vendors that sell them) you in effect end up with the original 918. The 1518's have more surface treatment to last longer. Both should be compatible with stock hardware. "Yeahdoug" (I think) is a PAC representative, shoot him a PM with technical questions. Find a vendor that has them.

Here you go, Speed Inc. carries them:

Link

JPH

iTrader: (2)

Crane rockers and LS6 springs= harmonics around 5700k+! This is not a good mix, unless you want to shift the car early all the time, to keep from triping the knock sensors because of spring surge. I suggest Crane dual springs #144832-16 in a kit from Vinci Performance, or you opt with Cranes #99831-16 beehive spring. But usually dual springs are recommended. Vettenuts has run there rockers for years, both 1.7 and 1.8's on dual and beehive springs and they work both ways. If you do run a beehive springs, choose wisely. Crane #99831-16 (PAC made) or the springs that Vettenuts mentioned also.

The Vigg

iTrader: (3)

What about the patriot gold dual spring kit? Would those work well?

Tainted

iTrader: (9)

patriot golds are well known and well proven to be a good spring. I suggest you hold off on these rockers unless you know for sure that you dont want a cam in the future.

The Vigg

iTrader: (3)

I am sure I won't be going cam in the future. I do not need any more lope or emmisions concerns. Again this is on a Cadillac CTS V. Will the patriots require any machining to the heads? Any down sides?

lstvr

I have just ordered a cam grind to take into account my high lift rockers, i have 1.85 Comp cam rockers, but i have now decided i need more duration. No one seems to think its a problem, so it is possible if you change your mind. I got a 35bhp peak gain out of my rockers, just for the record, but mine is a 383.

vettenuts

iTrader: (4)

I have been told that the Cranes will tickle the Patriot harmonics and not to use them.

JPH

iTrader: (2)

dunno man, I suggest you stick with what me and vette told you. We both have alot of experience with there rockers and know what and what not to do. with them.