Importdestroyer

iTrader: (1)

My set up right now is 220/224 .583/.583 114 with cranes 1.89 gold rocker arms. We ran into an issue in the upper rpm's and cant necessarily attribute the dip in power at 6k to the rocker arms, but I do know of several other's with the same issue, in the same RPM's, with the same set up.

So I was thinking of going back to stock rocker arms, and then I figured I would go with SLP's 1.85 rocker arms as instead of dropping the lift to .551 with the 1.7's they would actually increase the lift to right about .600/.600

Im concerned with ramp rates, as the cam is only a 220/224. I am using Patriot's dual gold springs. And will be using stock length hardened pushrods.

Im hoping I will eliminate the harmonics issue here, but dont want to create another problem with the valvetrain with the aggressive ramp rate. Opinion's please!

Importdestroyer

iTrader: (1)

TTT Im short for time, I have a local seller for these arms who is waiting patiently for a response. Opinions needed.

DaddySS

Is that a Crane cam and if so haven't they solved the issue with a spring swap? How do you figure the SLPs will help - just guessing that a different rocker will give different harmonics? I would call Crane - they can advise you best.

SideStep

YES, several have had issues with other than factory rockers... 90% go back to the factory rockers and solve their problems... Just bolt them (the factory ones) then dyno again... I am betting that will be the end of your problems...

Importdestroyer

iTrader: (1)

Good point, yes crane has just finished a set of springs designed to eliminate this all too common issue with their rocker arms. At this point Im not sure if I want to throw down another $300 for springs in hopes that it would alleviate the harmonics issue, when I know a sure fire fix is to go back to the stock rockers.

I DONT know of anyone having issues with patriot dual gold springs, .580-.60# lift cams, and stock rocker arms. I DO know of 4 different people all having/had identical issues with the crane rocker arms.

Question is, will changing to SLP's 1.85 rocker arms solve the issue, without creating another with the cam Im running. Again 220/224 .600/.600, I havent heard of anyone running this much lift with that kind of duration.

Would I be better off throwing the stock 1.7's back on and reducing the lift to .551/.551?

Importdestroyer

iTrader: (1)

At the sacrifice of power, what kind of power difference are we talking between .551 and .600? I know for sure it will get rid of the dip in power at 6k.

Importdestroyer

iTrader: (1)

I dont know if its an appropriate comparison, but a stock LS7 cam is 210/230 .591 .591 120 LSA, with 1.8 rocker arms. GM managed .591 with 210 duration, so maybe Ill be ok with .600 lift and 220.

SideStep

Man.... if you want .600 lift get a cam that has that much lift with 1.7 rockers ( I know, easy for me to say.....) Assuming you could ever get the longer rockers to work, there is going to be a difference in the power output for like cams separated by .050 lift... Why not just bolt the factory ones on and pull a dyno run... you may not be that far off, considering all the crap the longer rockers are causing you....

Importdestroyer

iTrader: (1)

Yeah Im not ready for a cam swap right now, It would cost me another $300 to retune for sure on top of the cost of the cam, and the hassle of doing it on a y-body, its a little bit different than just moving the radiator, the power steering rack has to be removed to get the crank pulley off. And the end result might be another 15 rwhp, not worth it in my opinion. Remember I cant go all out as Id like to keep this smog legal, so it cant get much bigger than it already is.

Id just like to change rocker arms, and get rid of that dip. I am considering SLP's 1.85 rocker as I would be able to keep lift near .600. So the question remains, is .600 too much lift for a 220 cam, and has anyone ran into any valvetrain issues such as valve float or whatever with SLP's rocker arms and .600 lift.

MNR-0

Crane 1.8RRs here on a comp 212-220 cam 0.590/0.600 total lift and comp 918 springs. Love it - no dip.

Importdestroyer

iTrader: (1)

\

Did you ever have a dip in power initially?

ArKay99

iTrader: (1)

Sounds like valve float to me. Even though you are only running 210 duration, with 1.89 rr you are amplifying the ramp in the lobe. If it's an X-ER lobe the acceleration must be sick.

Importdestroyer

iTrader: (1)

Im not running 210 duration. If you look at my initial post I said I was running 220/224. I dont know if its valve float, I am using Patriot dual golds that have plenty of pressue. Again, I am considering going back to stock rockers as I think it will fix the dip in power at 6k, and I also am thinking of going with SLP's 1.85 rocker, as its basically stock rocker with a 1.85 ratio. My concern is running .600 lift with 220 duration. Thats an aggressive ramp.

And Id like to know if anyone is having any other valvetrain issues with SLP's 1.85 rocker. I think the problem with my valvetrain set up is indeed Crane's rocker arm, something to do with the geometry possibly, the vague method to attain lifter preload, or the additional weight of them. I am basing this assumption off of the fact that I know of 5 different people with this same set up with the same dip in power at the same spot.

Vinci claims its the springs, well I dont know of any other PP Head owners having similar if any valvetrain issues with the supplied dual gold springs and high lift cams with stock rocker arms up to 6500-6800 rpm.

gun5l1ng3r

I also think that the ramp rate might be a little too steep, even if you do have strong springs. Try the stock rockers and see what it dynos...

Importdestroyer

iTrader: (1)

Yeah I wonder what kinda hit in power Im gonna take by dropping the lift to .551 with the stock rockers. Im sure I wont have the dip at 6k, but at what expense? Ill probably dyno 410 rwhp at 6500 with the stock rockers and .551, instead of 400 rwhp at 6k with the crane's and .600. I wonder how the entire power band will be affected.

mrr23

iTrader: (3)

xtrooper did the opposite and got rid of his power dip and gained power. went from SLP 1.85 to the 1.8 accelerated lift rockers. search for his post. he also swapped to the crane springs. don't remember what he had before.

krexken

I don't see the big lift with the short duration as a problem. Ramp rate is how the lobes are ground, not the rocker ratio, correct? Your cam won't care what rockers you run. Your springs must certainly be up to the task of closing the valves properly. I think the SLPs may only aggravate the issue but then again what do I know. It would indeed be an interesting experiment with the SLPs and you can always sell your used parts here. LOL

Importdestroyer

iTrader: (1)

I attempted to contact xtrooper, I heard that he had to shim a set of 918 springs to get rid of the harmonics issue with VHP's arms.

Im over it, these arms and the cam are for sale. After reassurance from Roger that the solution to his defective product is to pay more $$ to VHP and Crane for a set of springs that may or may not work, I am moving on to do the valvetrain the right way, with the stock rocker arms, needle bearings and all.

mrr23

iTrader: (3)

be careful with that 'defective product' saying. btw. xtrooper went from comp 918 to the crane springs. shimmed those and got rid of the dip. it's just a matter of finding out what's causing it and fixing that. i got rid of mine with tuning. he got rid of his with shimming the springs. both of us using the vinci/crane springs. and mine aren't shimmed.

like i said over on ls1.com. if you haven't sold the stuff in 30 days, i'll purchase them for my car.

mrr23

iTrader: (3)

this subject keeps coming up. what i keep asking is what makes this 'dip' go away if you use the exact same ramp that occurs at the valve?

cam #1 220/224 .589/.589 LSA 114 w/1.7 rockers X-ER lobes
cam #2 vinci 066 220/224 .551/.551 LSA 114 w/1.8 rockers that bring total lift to .589/.589

both cams having the exact same valve events at the valve.

spring control? both have the exact same valve movements.
rocker weight? the vinci/crane rockers (if i remember correctly) are 5 grams heavier than stock rockers over the valve. is the 5 grams actually contributing to it? if so, then why isn't this 'dip' more consistent?