1.6 rollers

[lt1maro]

i was thinking of putting on 1.6 roller rockers but my mechanic says that without a cam, i would only see about a 5 hp increase. Is this true? What type of gains could i expect with the rockers with the mods in my sig.

[Kevin - Blown 95 TA]

I think it is more than that. It increases your lift by approx. .030", helps your tune by replacing non-precicion parts, and cools your oil as well. I like that mod and I think it is worthwhile.

[fastTa]

The increased lift along with the decreased friction due to the roller fulcrum and the roller tip will give you at least 20 hp and more likely a little more.

One thing to note. The stock valve springs will be marginally close to coil bind with the addition of the 1.6 rocker. So while your there, I would do new springs and valve seals as well. This can be done w/o pulling the head.

[AmericanZ28]

Originally posted by fastTA
The increased lift along with the decreased friction due to the roller fulcrum and the roller tip will give you at least 20 hp and more likely a little more.

One thing to note. The stock valve springs will be marginally close to coil bind with the addition of the 1.6 rocker. So while your there, I would do new springs and valve seals as well. This can be done w/o pulling the head.

Ive heard that using LT4 springs as a replacement is a good, inexpensive way to go. Is This true, or are there better, cheaper alternatives? Also, will the pushrods stand up to the increase pressure of the LT4 springs? I'm considering this as my next mod, and are looking into some Summit Brand RR's as they are much cheaper than most others. Now do I need 3/8" stud rockers, or 7/16"??

[fastTa]

Originally posted by AmericanZ28
Ive heard that using LT4 springs as a replacement is a good, inexpensive way to go. Is This true, or are there better, cheaper alternatives? Also, will the pushrods stand up to the increase pressure of the LT4 springs? I'm considering this as my next mod, and are looking into some Summit Brand RR's as they are much cheaper than most others. Now do I need 3/8" stud rockers, or 7/16"??

It really depends on how much gross lift the valve spring will see. This will primarily depend on the amount of lift on the cam you choose.

GM rates the LT4 spring to haandle .540" of lift but that is actually a little conservative. The LT4 valve spring has a solid height of 1.220". This is the height of the spring completely compressed. The normal installed height of the LT4 spring is 1.780". So if you subtract the solid height from the installed height, you actually get .560" before coil bind.

So generally speaking, as long as you stay under .560" of lift, the LT4 valve spring should be fine considering you aren't revving the snot out of it.

As far as the rocker stud diameter, my philosophy is "Bigger is Better". The 7/16's are much stronger and won't allow as much "stud flex" as the 3/8's will. The less "stud flex" the more accurate the valvetrain geometry. The more accurate the valvetrain geometry, the more horsepower!!

[SteveH37Formula]

The stock LT1 heads and GM Performance parts LT4 heads have 3/8" studs. Factory LT4 heads have 7/16 or 10mm studs.

[AmericanZ28]

Thanks guys! My prayers have been answered! LOL! Heres the description of the exact ones I want to get. Should I have any problem installing these on my car? Will I need Guides as well?

Vendor: Summit Racing Equipment
Product Line: Summit Aluminum Roller Rocker Arms
Material: Aluminum
Finish: Anodized Blue

Lightweight horsepower.

Chevrolet: 262-400, 1.6 ratio, 3/8 in. stud, aluminum, anodized blue finish, roller rocker arm set

Save some weight and build horsepower with our Summit aluminum rocker arms. The bodies are CNC machined from high strength extruded aluminum and are heat treated for reliability. To guarantee silky smooth valve operation, we gave them premium needle bearing fulcrums and roller tips. We even include lock nuts and an Allen wrench with them for a quick installation.

Sold as a set.

[Dave M]

I think Summit has an application specifically for the LT1, with centerbolt valve covers. Those ones you posted I'm not sure would fit, I think they are for older engines, but I could be wrong. I'm pretty sure I've seen an LT1 specific application (or at least ceneterbolt valave cover application) in their catalog.

[fastTa]

LT1's use the same rocker arms as a small block chevy(SBC) regardless of the valve cover type.

I wouldn't recommend using an aluminum rocker on the street though. Aluminum is used in racing motors because it is lightweight, but at the sacrifice of durability. I would use a steel rocker arm for street use AmericanZ.

[Kevin - Blown 95 TA]

Crane has narrow body rockers for SBC centerbolt valve covers and normal body rockers for older SBC standard valve covers. You also have to use self-aligning rockers for applications that do not have pushrod guides. If you have guides (non-stock) you cannot use the self-aligning rockers.

[Dave M]

Originally posted by Kevin - Blown 95 TA
Crane has narrow body rockers for SBC centerbolt valve covers and normal body rockers for older SBC standard valve covers. You also have to use self-aligning rockers for applications that do not have pushrod guides. If you have guides (non-stock) you cannot use the self-aligning rockers.

That's what I was thinking of...

[fastTa]

There's no such thing as an LT1 specific rocker arm. They are the exact same rocker used in a SBC.

The thing with aluminum rockers is the fact that they are designed with a litle more mass in order to be strong enough. In the case of aluminum rockers, yes there are narrow bodied versions designed to provide clearance for late model, centerbolt valve covers.

Aluminum rockers really should not be used on the street though.

So all of the steel rockers out there are the same for SBC and LT1 regardless of valve cover bolt specification.

[AmericanZ28]

Ok, now you guys got me thinking..... Summit also sells Narrow Body Rockers, but at a higher cost. At that price, Id be better off getting the Comp Cams RR's. So will my primary choice not work due to the wider body? If not, then these are my next choice..


Vendor: Competition Cams, Inc.
Product Line: Competition Cams Pro Magnum Roller Rocker Arms
Material: Chromemoly Steel
Finish: Machined

The strength of steel, the light weight of aluminum.

Chevrolet: 262-400, 1.6 ratio, 3/8 in. rocker arm studs, chromemoly steel, Pro Magnum, roller, rocker arms

[fastTa]

The Pro Magnum is a very quality rocker. And remember what the other Kevin said, if you are going to use hardened or chrome-moly pushrods (which I recommend), then you need to use guide plates and use the NON-self-aligning rocker.

But if you plan on using the stock pushrods, then use the SELF-aligning rocker , and there will be no need to use guide plates.

[N20LT4Bird]

Originally posted by fastTA
The Pro Magnum is a very quality rocker. And remember what the other Kevin said, if you are going to use hardened or chrome-moly pushrods (which I recommend), then you need to use guide plates and use the NON-self-aligning rocker.

But if you plan on using the stock pushrods, then use the SELF-aligning rocker , and there will be no need to use guide plates.

Ive used the pro magnum rollers on another engine I built for a TPI car. I did have to modify the valve cover to fit over the rocker body. The rocker was too wide. I dont know if this is the case for the LT1 or not. I am running crane gold's on my current car and they require no mods to the cover. If you do have to modify the valve cover to fit the pro magnums, its not a big deal - just a little tweaking