Gen3FTW

Hi guys!
So im thinking of buying some roller tip 1.6 ratio rockers for my 1985 Z28 Camaro with a TPI 305.
First question is do I need self aligning or not?

And did I calculate this right?

With Stock 1.5 Rockers

Intake Lift: .403
Exhaust Lift: .415
Intake Duration: 202
Exhaust Duration: 206
Lobe Seperation: 114.5

With 1.6 Ratio Rockers

Intake Lift: .443
Exhaust Lift: .454
Intake Duration: 215
Exhaust Duration: 219
Lobe Seperation: 114.5

Thanks!

dimented24x7

iTrader: (2)

The lift changes proportionally, but the duration does not. The 1.6's have a slight impact on the duration, but its not proportional like the lift is. It may increase the duration @.05 by maybe a few degrees.

The heads should have guide slots, so standard rockers should work. You may want to check teh geometry as teh pushrod is moved closer to the inside of the guide slot.

AlkyIROC

Old valve lift divided by rocker ratio equals lobe lift. Lobe lift multiplied by new rocker ratio equals new valve lift.

Intake 0.403
Exhaust 0.415

Becomes

Intake 0.430
Exhaust 0.442

As mentioned above, duration is affected very, very little.

Especially with such low lift factory cams, going from a 1.5 rocker to a 1.6 rocker is just a poor mans cam swap. Although you're going very inexpensive with just a roller tip rocker, it's unlikely you'll see much of any kind of gains. A proper cam swap and any kind of full roller rocker would be a better choice.

DJK90IrocZ

Hello all.....kinda of new to this valve lift and rocker ratios......

I wanted to change out my stock 350 rockers to roller tip, to have less friction and heat loss, but I really dont want to swap the cam, lifters, rods...etc....

If I just replace the rockers from stock to 1:5 roller tips...will that give me any better hp/torque gains....??

Thanks in advance.

MC305SS

Reading everything there is on the subject, lower lift camshafts respond much better to this swap than higher lift ones.
Duration changes at the .050 lift area are on the order of 2-3 degrees since .050 lift will hit sooner and last longer.
I did 1.52's last year and also did it on another motor a few years back. It made just enough power over where it was I could just detect it. I think if you swapped out to 1.6's you'd see IMO around 12 h.p. maybe a tad more.
The numbers posted above about the new lift heights coupled with a now 204-208 duration cam would put it around the same gain. If you read around the net about the summit 1102 cam swaps in L69 camed motors, that cam change is around 20+ H.P. and this would be close, just lacking duration on the exhaust side.
I plan on doing this change when I do the head change.
I got a extra set of 081's which I have had rebuilt and some extra work done to and I'm going to add the 1.6's so I'm hoping on the order of 30+ just by doing this.
Cam change would be cheaper, but I have all ready done the timing chain and gears along with a host of other work and I'm not going to remove half the front end again.

freaky

i'm going to a lt1 cam im my l03 motor an i'm gonna use 1.6 roller rockers . i'm hoping for sum gains there but i'm tryiong to find a good set of vortec heads first an change everything at once .

88formula305tpi

i just took my comp cams 1.6 roller tips off for the stock 1.5s if anyone wants them. It idles smoother less valvetrain noise. i noticed i lost a slight amount of higher rpm power but the lower rpms feel better now. I think a daily driver should stick with 1.5's with a stock engine. i was thinkin of gettin a set of 1.52 roller tips from comp cams.

TNT_Z28

ive been contemplating the same thing. (whether to go 1.5 or 1.6)

it all depends on your cam and heads. the real power and torque to be gained is with a set of FULL ROLLER rocker arms. roller tips only adress part of the problem. the higher ratio might give you (depending on your cam/heads) 2-4 more hp across the board. the real gain is, as i said before, from the friction loss. FULL ROLLER rockers adress the issue alot better that roller tips

TNT_Z28

look at ur factory rocker arms... shouldnt need self aligning (with factory heads in the first place) especially if your origanal ones arent dimpled

kad5118

I just purchased some full 1.6 ratio rocker arms for my l98 engine.it has 138,000 miles on it

formula forever

how does your l98 like them? Can you run them on stock heads and springs?

rwstegne

how does your l98 like them? Can you run them on stock heads and springs?

kad5118

well to answer your question i think that i runs good it has a little bit more punch but i think that it will work well if my intake pushed more air.bit for what its works it performs as good as my wifes 08 infinity g35 from take to highway speed.and yes you can run stock springs on them its just when you go up in cam size like say a 262 or 268 duration cam it would be a good idea to just go with ls6 valve springs. the lt4 valve springs are a good choice also from what i have been told.