jeffie86/96

I have question about using 1.6 rockers on our engines, if you do a cam change and specify what lift and duration you want what is the use in using 1.6 rockers? In my humble opinion you are going to have more stress on the valvetrain over 1.5 units. I could see using them to pick up more lift without a cam change but don't see the advantage without. Any thoughts? :chevy

bjankuski

You are correct, if you pick the cam specifications that you want with the 1.5 ratio rockers already figured in to the plan, you will not have to change to 1.6 ratio rockers. The 1.6 rockers are a quick way to add some lift and duration to a cam that may be too small to start with.

65Z01

Well it realy depends on flow numbers with your cam and heads. If you are at the max already then of course 1.5s would be the choice, else the 1.6s are it. If the new cam has exactly what you need then I wouldn't go with 1.6s. Either way full rollers would be nice though.

With my stock cam and heads I've gone to the 1.6:1 full rollers intake & exhaust with no idle problems. With an aftermarket cam, ??? The biggest issues would be coil bind and max lift on the valves.

Don't foreget that they not only give about 7% more lift but effective increase duration at .050" by about 2deg (of course no change at zero lift). They do increase the angle on the pushrods a little so I guess stress would be up a little.

jeffie86/96

I was kind of thinking in those directions, I purchased 1.5 roller rockers for my new engine and specd out the cam to what I wanted. Chevy pushrods are kinda long and spindly so taking the extra stress off might be a really good thing.


[Modified by jeffie86/96, 7:59 PM 10/19/2001]

Chris@SD

Actually, that is just not true. You are using leverage to pick a valve up higher in the same duration, which means you can use a less agressive cam to get the desired results. This means less stress on lifters, springs, etc. You cannot go wrong with the Comp Cams Pro Magnums Roller Rockers.

Let me know if I can help. We have them in stock ready to go as well as all the other accessories you need, (Springs, pushrods, etc.)

nickd

I thought changing to 1.6 rockers only effected lift and not duration ?

2FST4U, do you have the self aligning CC 1.6 Pro-Magnum rockers if so how much ?
I have 47k on my stock springs, would you recommend going to a stiffer spring with 1.6's, getting new stock springs or is it ok to use my current ones ?
thanks.

Chris@SD

We do have them. If you plan on modding your car any further, I would highly recommend the non self-alligning ones and purchasing 7/16" studs, giudeplates, and hardened pushrods. We have a package with all this listed in our Corvette Forum mall. Send me an email or call me if you need any help.
Thanks,

nickd

Thanks

jeffie86/96

Advertised duration will be affected since the figure is taken at .050" valve lift (if I am correct) and 1.6 rockers open the valve at a higher rate. Therefore .050" lift will occur sooner. Also consider that while 1.6 rockers make it easier for the valve spring to close the valve since it can more easily push dowm the pushrod and lifter it is mechanically harder for the pushrod and lifter to open the valve. Isn't physics fascinating.


[Modified by jeffie86/96, 2:32 PM 10/20/2001]

mackeyred96

When Cartek did my top end they built all the lift into the Comp custom cam. I'm using the 1.5 comp pro mag rockers.

jeffie86/96

When changing to higher lift with used springs you may experience problems with coil bind and breakage, seems valve springs get used to being opened only so far after a few thousand miles and tend to break when asked to open further. coil bind is another matter entirely, if you try to compress a spring too far the coils will stack up not compress any further breaking lots of stuff (like pushrods) . I would suggest using new springs with a cam change, another factor is closed spring rate which affects lifter preload. :chevy

vette punk

No one has answered the question pertaining to springs. Do you or do you not need new/better valve springs when using the 1.6 full roller rockers with a stock camshaft.
Inquiring minds want to know.................
Jim :D

DougSilver

Re: spring upgrade. Seems this is one of those questions where you can find opinions on both sides. I recently purchased an LT-4 "hot cam" kit (minus the cam) so I have the 1.6 roller rockers, heavier springs, and associated hardware ready to install. I have asked several mechanics whether I really need to change the springs (this will add a few hours of labor to the overall job). I have had several guys tell me that since my car was fairly low mileage (40K) the stock springs would "probably" be fine. The thing I have heard about using the stock springs is that these could be "close" to coil bind. However, the opinion of a few mechanics I have spoken with is that there should not be a problem with stock springs in good condition, especially if you don't push the rpms ridiculously high. Nevertheless, since I have the springs it seems a waste not to bite the bullet and pay the extra to have these installed.

jeffie86/96

It all depends on how much lift you have to start with. the lobe lift is multiplied 1.5 times at the valve by stock rockers and 1.6 times by the aftermarket hi po units, you must know how much lift will be tolerated by the stock components. 40000 miles on stock springs may be pushing it for a 1.6 change. Just depends how lucky do ya feel. :chevy

nickd

I think jeffie86/96 post above answered the question.
Thanks for the great info guys.