ratio rockers

[89rdstr]

has anybody put 1.6 ratio rockers an a L-98? do they ad power or ad lope to the idle? are they worth the time & money? thanks

 

[Hrtbeat1]

Yes, I've done it. Yes, you will gain some HP, not so much more lope, maybe a little. With the larger ratio you gain a little lift from the cam. Considering that every little bit adds up to more HP with these cars, I would consider it worth the effort, especially if you are planning on doing other mods like head work or a cam swap at a later time.

 

[AdvancedAutoCC]

you'll gain some more valve lift, but no appreciable "lope" from the camshaft (rockers don't affect duration or lobe centerline). I did them on my L98 and picked up some seat of the pants performance. I put some on Legion21's LT1 and he picked up a few extra HP.

I've got 1.6 roller rockers in stock, ready to ship in 1.5 and 1.6 self-aligning. Let me know if you're interested in some.

 

[Doktor-t]

Rockers

I put some Crane stamped (stock style) 1,6 ratio rockers on my Trans AM -88 with 350 TPI engine and I think it was worth it. Some torque is doubtless added. No change in idle quality either.

The only thing is that I´ve nowdays been told that it is important to swap the valvesprings. Why I don´t really know. Someone know?

My Trans AM worked fine fore years thou.


Tobias, Sweden

 

[Legion21]

As Bob stated he put 1.6rr's on my car and my ET's went from 12.63 to 12.56 with very similar DA's and picked up almost 3 mph in the quarter.

Greg

 

[Vettefan87]

I have 1.6's with my car. I believe 1.5's come on it stock. Definetly worth it every little bit of HP helps.

 

[geekinavette]

The only thing is that I´ve nowdays been told that it is important to swap the valvesprings. Why I don´t really know. Someone know?

The valve springs will only compress so far, with the added valve lift of the larger rocker arm ratio (valve lift = cam lift * rocker ratio) you have to make sure that the springs do not compress fully before the valve reaches full lift. That does BAAAAD things to cam lobes!

You also have to make sure that the spring rate is such that the valves do not "float" at high RPM. Valve float is when the spring rate is not sufficient to fully close the valve at higher RPM.

Bill

 

[grumpyvette]

changing rocker ratios is a good tunning aid but its not a good substitute for a cam swap,which can easilly give you 3 to 5 times the hp improvement (WHEN MATCHED to the correct rear gear and component changes) ,sure you can tweak the flow and gain a few hp, but gains in hp are usually more the result of the closer tollerances and lower friction when swapping from a stamped to a roller rocker VS just the slight flow increase the rocker ratio change caused
read thru these

http://popularhotrodding.com/enginemasters/articles/hardcore/0511phr_ratio/

http://www.compcams.com/information/Products/rockerArms/ProMagnum.asp

http://www.vetteweb.com/tech/0204vet_rockers/



http://www.lmengines.com/rocker_arm_changes.htm

 

[vader86]

They usually add about 15hp or so to L98s, so do it.

 

[Black Bart]

you'll gain some more valve lift, but no appreciable "lope" from the camshaft (rockers don't affect duration or lobe centerline). I did them on my L98 and picked up some seat of the pants performance. I put some on Legion21's LT1 and he picked up a few extra HP.

I've got 1.6 roller rockers in stock, ready to ship in 1.5 and 1.6 self-aligning. Let me know if you're interested in some.

Here is article explaining how rocker ratio changes duration and lobe centerline. http://popularhotrodding.com/tech/0607phr_camshaft_basics/lifters_pushrods.html