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.
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."
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.
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.
my e-mail is firstname.lastname@example.org.
In general, did they line up OK without guide plates?
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.
John and Tom covered this subject well.
the picture is in the mail
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