Rockers

[Bo Dillingham]

It's Sunday afternoon and I just read an article on roller rockers in the recent issue of Vette magazine (for some reason, they sent me a complimentary copy), and proceeded to go to CAC and read about a years worth of discussions from you, the people I trust the most.
The article states that most original GM stamped rockers are more apt to be around 1.47:1 than the 1.5:1 that they are designed to be. It further states that they tested a set of Comp Cam Magnums at 1.52:1 with very good results (3 to 17% HP increases, depending on RPM, etc.)
The article also warns of things like clearance problems, spring binding, and more.
In a response to my question about "rebuiding a 300hp 327" some months ago, Tom Bryant mentioned roller tip rockers, but did not mention a brand name.
Does anyone have some pros or cons regarding rocker upgrades for the 300/327? Can you give me specific brand names and/or models? Does anyone have info on a model that "bolts in" without extensive rework?
As usual, any information or comments will be much appreciated.
Bo
65 convertible.

[WayneC]

I don't have direct experience with roller rockers, but I also am thinking ahead to when I need an engine rebuild, and have saved comments that appear on various Corvette forums. Here are a couple on the subject of rockers:

"Comp Cams Magnum roller-tip rockers if they have to fit under standard-height valve covers, or Comp Cams Pro Magnum cast stainless full-roller rockers if the valve covers don't matter." (2 posts recommended the Comp Cams rockers)

"the roller tipped rockers from Summit that use the ball pivot at the fulcrum are a reasonably priced alternative and fit under the Corvette valve cover."

[JohnZ]

The Comp Cams roller-tip rockers will fit under stock valve covers because they use stock rocker balls and nuts, whereas full-roller rockers use Poly-Locks, which require taller covers. Keep in mind that the Comp Cams roller-tip rockers require guide plates, which means machine work on the stud bosses to get a flat surface for them to seat on unless you already have screw-in studs.

[yooperod]

If anyone wants a picture that shows how comp magnum roller tip rockers line up (without the use of guide plates) I'll Email them to you. A good product but they did not mention the need for guide plates,I did not want to drill out the "cast" guides because the engine was already assembled. I suppose I could have filled the valley with rags and drilled them.but I went with the regular comp rockers.
rod

[Bo Dillingham]

yooperod,
my e-mail is bodillinc@yahoo.com.
In general, did they line up OK without guide plates?

[Tom Bryant]

Roller rockers are available in self aligning or regular. Self aligning have a lip on both edges of the roller to keep the roller on the valve stem. If yours don't have the lips you need guide plates. Other wise there is a very real possibility of the roller working it's way off of the valve stem and costing you a bunch of money. In fact it will happen so don't take a chance on ruining a head. Some of the newer Chevy heads that use factory rockers have a specific push rod hole width to act as a guide plate. I do think that the GM roller rockers are self aligning though.

I don't think that all companies make self aligning rockers. Comp Cams, Crane, Crower, ect all make a quality product. Most make a lower priced roller rocker and a high priced one. The economical ones are normally all you need for a street engine with street valve spring pressures. All out high dollar ones are usually overkill for our purposes.

Tom

[yooperod]

John and Tom covered this subject well.
the picture is in the mail
rod