Hey everyone,

I have an L98 from a 91 vett with aluminum heads. My question is if I up grade to 1.6 roller rockers to get a little more lift can I keep the stock valve covers or do you need deeper ones?

 

The ratio change is done by moving the pushrod location slightly closer to the rocker stud. It doesn't change any other aspect of the rocker so wherever a 1.5 rocker will fit, so will a 1.6 rocker.

Rocker design however may cause problems. The aluminum roller rockers have a larger body than the stock stamped steel ones. This "might" cause interference with some rocker covers but normally doesn't. If you use a high end rocker like the Comp Cams Pro Magnum (old name, they've upgraded), they'll fit even better but will cost you a lot more.

Going from a stock stamped steel rocker to even a 1.5 roller rocker will be an improvement. The rocker ratio with stamped steel rockers is nowhere close to being exact.

If you went from a 1.5 roller rocker to a 1.6 roller rocker, you might see a 5ph gain from the increased lift.

As long as you're using a stock cam, there's never a problem from using 1.6 rockers. If you use an aftermarket cam with more lift, there are a lot of clearances to check to make sure using a 1.6 rocker won't cause any problems.

 

I am assuming I have "blue" Summit roller rockers that are 1.5rr. Would I know or see any improvement going with 1.6?

(I'm assuming this, because they were blue and the summit rockers that are blue are 1.5, but idk if they are summit brand either)

 

Thanks for the info. I was looking at the Comp Cam rockers. And yes the cam is stock. I just have to figure out what stud size it has.

 

All SBC studs are 3/8"

 

Sweet that cleared a lot up.. ALKYIROC u should make that first post from u a sticky for others that are interested in upgrading there valve train..

 

People will probably find it if they use the feature

 

Has anyone used the ProForm roller rockers? I was looking at the Comp ones but notice I could save a lot with the ProForm ones. They are listed to work with the center mount valve covers as well.

 

unless someone upgraded. when i bought my rr i ordered 3/8 and found out that mt motor had 7/16 studs. just something to think about

 

To run rolller rockers under the stock L98 Valve cover you need to grind down the drip tabs under the valve covers you see them when you flip them over.

A lot of us Vett guys end up doing this are self so we can use roller rocker arms under the stock Valve covers.

On the C-4 Vett we can't run tall Valve covers on mine Tall Valve coves willn't clear the windsheild wipper motor and some of the later years they hit the A/C compresser un less you cut and reweld the covers to fit.

 

ProForm have a pretty shady reputation. A lot of their stuff comes poorly machined and doesn't always fit right. I had a set of roller tip rockers from them and busted two tips in like 1500 miles.

This is not to say their products WONT work, just that they have been known inthe past to be less than stellar. You get what you pay for.

 

Mine are ProForm 7/16 RRs. No problems to date, but I don't race, and haven't been to the track so they've only been through normal wear & tear.

 

I have a set of cheep China brands in my motor now I going to swap them out for a set of Comp Cam Magnum Ultra SS.

Yes they are over kill for what I need them for but I dont have to worry about them failing on me 100 miles away from home.

I read lot engine failure due to the cheeper China brand RRA Like other have said pay now or be walking sooner or latter.

 

What exactly do you mean by "drip tabs?" are they those little flanged sections that the bolts slides into? I have the same issue. Im out of ideas but since I ran into this thread via search tab, I'm more releived that I dont have to buy aftermarket covers. What about the baffle for the PCV valve? Its a bit bulky. SHould I grind down the flanges on the skirt, or smash'em with some vice grips?
(Here is my thread covering my issue with pictures, https://www.thirdgen.org/forums/tech...-wont-fit.html )
Clearanceissue-valvecover4.jpg?t=1294284280

 

Run the comp magnums... roller tip design and a lower profile than the promags. THey will clear the valvecovers. The promags are significantly taller due to the nut that fits on top. I dont know if they clear the covers. I run a tall cover for these now.

I found about a tenth in the 1/4 with the rocker arms. Should be more tho, as it was running pretty lean. Before the rockers, i put down 246whp with a 12.5 or so air fuel ratio. After new injectors and 1.6 mag rockers, it put down 254whp at 14.4 air fuel ratio...so it was very lean. I expect another 5-10 hp hopefully with richer tune but never happened. So they should give good gains for the 170 bucks you would pay for them.

 

The drip taps are on the perimeter type Valve cover.

What I know about Center bolt type you need to get the narrow body Roller rocker arms.

I have Aluminum RRA on my motor now I going to swap them out for Steels they say they last longer.

Aluminum ones what I read they work harden after time and they mite crack on you, If you take the Valve cover off and check them every now and then I gusse it will work but I want to beable to close things up and forget about them.

 

Thanks for the info. I did notice that they have ones listed as narrow roller rockers to fit under center bolt valve covers.

 

The GMPP 1.6's will work with our stock centerbolt valve covers. I just did a bunch of research on this.