stingry

I have the stock (and old) GM Rockers in my rebuilt 1970 engine. About to replace them with some new rockers. Engine is pretty much stock. New L46 CAM, Magnum push rods and camel hump heads with 2.02/1.6 valves.

Has anyone used the Comp Cams Roller Tip rockers and had a measurable HP increase?

Is the HP increase related to better stamping the rockers or due to the roller tip?

Any thoughts?

big_G

I bet half the stuff in the mags. make little or no hp. I include roller-tipped rockers in that group. Of course, accurate rocker design is a good thing. I have never seen (in print media) any tests showing any improvement.

evil herbavore

If the valvetrain geometry is less than spot on (almost guaranteed) I bet they cut down on valveguide wear a bit.

bobs77vet

roller tipped is only the tip of the ice berg.....the fulcrum is where the gains come from.....if i were to do this it would be full rollers

SteveG75

Mr.L

they are better than stamped steel stock GM. Go for the $ and get the full roller.

enkeivette

I second that. Full roller or bust. And if roller lifters can yield 30-50hp I don't see how full roller rockers won't add hp.

And you shouldn't pay more than $150. Mine are annodized blue full roller rockers made from aluminum and I payed $130.

The_Dude

Dep must not be paying attention these days.

Jughead

The bus driver is asleep at the wheel.

norvalwilhelm

This is the big reason I use them. To cut down on side loading and prevent guide wear. I know that GM went to roller rocker folcrums on all their 3800. They must have thought it help to go to the added expense of rollers.

jimvette999

These are good ones. I've had no problems with em'.

Jim

page62

You got the money burning a hole in your pocket, I say go for it. You'll at least be able to tell your buddies about the bling bling rollers under the valve covers. But the HP gains, which are nominal at best, are at the very high end of the power curve -- minimal bang for the buck.

mandm1200

I not so sure I would replace standard rockers if the existing ones were fine. If I needed new rockers, then its a different ball game. The price will vary on name brand and quality. I don't think a $300 set is required for a street engine. The full rollers may only cost $80 more than standard rockers.

Roller tips will buy little if any hp gain. Full rollers should add a few ponies due to the lower friction. Well, they don't really add hp; they save hp. The amount of saving should be proportional to the rpms. If the gain is 7hp at 6000rpm then I would expect so see 3.5hp at 3000rpms.
Look at the bang for buck. New alum heads at $1000 and 40hp gain; equates to $25 per hp. Roller rockers at $160 and 7hp gain; equates to $23 per hp. I don't see where these are any worse cost wise than new heads.

bb69

Guys,
I spent time designing roller rockers for the major automakers. The roller tip is worse than a good stamped rocker. A good rocker will have a crowned (radiused in all directions) valve contact area with a larger radius than the radius on the roller. The result is more of the rocker in contact with the valve tip. This distributes the load across a larger area, reducing wear. If the valvetrain is setup properly, the rocker will contact the valve stem slightly offset, so it will rotate the valve during cam events. The real benefit is a roller fulcrum. This is ths source of friction reduction. The reason for roller tips is 1) an aluminum rocker will need a steel insert anyway or the aluminum would fail from the contact pressure 2) marketing. Go with a roller fulcrum, and if you get a roller tip with it, OK. The difference in wear probably won't be evident before the 100,000 mile mark. Keep in mind the OEM's are designing engines for at least 150,000 miles now.

Ken

CA-Legal-Vette

I was thinking the same thing.

I'd would (and did) go with the full rollers as well. I doubt that you'll notice the difference in HP, but it does reduce crankcase oil temp noticably. As I recall, it was more than 10 degrees. That much differrence needs to come from a significant reduction in friction. Can't be a bad thing, aside from the cost.

Speaking of cost, keep in mind that you'll probably have clearance issues with your valve cover. I had to add a Summit spacer to clear the polylocks. Another $100 after the additional gasket.

It's only money.

Tom454

"The result is more of the rocker in contact with the valve tip. This distributes the load across a larger area, reducing wear."

You mean less wear on the rocker tip, per unit area?
I think that is what you are getting at?

I machine heads/valves, and I see more wear on valve guides than I do on rocker arm tips.

I tip & chamfer valve stem tips on every valve job I do, and it generally takes very few passes to true up a high mileage valve stem tip. The guides are usually toast. Stamped steel rockers seem to last a zillion miles. So maybe you are focusing on the wear on the roller part of the rocker itself, relative to the wear on a similar mileage stamped rocker?

Maybe the real benefit is a roller fulcrum to reduce friction at the rocker pivot.... but to slow down guide wear, the roller tip is more important?

Now, before we get slammed by the anti-roller gurus... I already know there is some doubt (myself included) as to whether a roller tip actually rolls when it is supposed to. I am going to test that theory shortly.... just bought a set of roller tips to play with just for the occasion. We shall see.

On the rocker rotating the valve... after doing a zillion valve jobs on factory, stamped steel valve trains... when I pull valves, I can usually see a match between pits in the seats, and corresponding pits on the valves face. So although the design theory sounds good, I can't say I would depend on a slight offset rocker spinning a valve.... they seem to take a "set" and stay put.

This is just what I see when I do valve jobs on high mileage "daily drivers".

If the products do in fact work as claimed, the roller tips would provide a benefit to the guy who doesn't have a lot of extra cash to burn (by being less expensive AND by saving the guides), and doesn't need the extra HP of full rollers. Sort of a financial compromise. I could see using either, based on the individuals goals.

I just built a Ford 5.0 +.030 and added the Ford full rollers.... looks way cool.... hope it performs as well as it looks.

bb69

Tom,
You bring up some good points as usual. When I say wear, I mean wear of the interface. This means the wear on the rocker and the valve tip. How much wear each sees depends largely on the material and its surface hardness. The amount of side loading put into the valve is a huge concern of the OEM's. We all have seen the smoke from cars with worn stems and seals. I worked with a guy that developed a program for us that determined all of these forces. To combat side loading, the rocker is not centered over the valve tip. The rocker is positioned with the center of the contact patch towards the edge of the tip. As the rocker moves, this contact patch moves as well, with the goal being to keep the contact patch as close to the center during the highest load and not falloff at full lift. You can see how complicated this gets when you include the offset for trying to rotate the valve. More offset means less room to work with on the rocking motion. Keep that in mind when putting a chamfer on the valve tip.

The offset does work, it's just a matter of for how long and under what conditions. I am putting together the engine in my Camaro, and when I was turning the engine over, the lifters were clearly rotating. It's the same principle. The problem you see is that wear, particles in the oil, expansion, etc can all affect how much the valve rotates. Eventually, it wears into a groove probably, as you have seen.

As for the roller tip rolling, it's a combination of rolling and sliding. We knew this was going on by the condition of the bearings (our company supplies most of the bearings for aftermarket rockers). The roller basically oscillates back and forth slightly. If the surface is lubricated well enough, it shouldn't matter. Think of you bearings, they slide. The only reason they work is because they are sliding on a film of oil. The rocker tip/valve stem interaction is also supposed to be floating on a film of oil, so rolling or sliding shouldn't be a concern. It really is dependent on how much area is in contact. The force from the valve spring, and the acceleration of the parts, is the same. If you spread it our over a larger area, there is less stress on both parts. Stress causes fatigue and fatique leads to failure.

Ken

toddalin

People can say what they want, but I find that they work for me and clear the stock valve covers. I don't know how much hp increase I get. I do know that my combination works very well for a relatively mild street engine. Before a Lars tune-up and some carb/air cleaner interface modifications, the little 331 was making 293 ft-lb and 293 hp at the wheels, so I must be doing something right.

I went with the 1.52:1 ratio and could have possibly picked up a little more power going to the 1.6:1 ratio, but this would have required that I clearence the heads and I just wanted to keep it simple.

My combination:

331 CI, pump-friendly 9.5:1 CR
K&N 14"x4" air filter, Corvette drop base and lid
Holley 600 dp, choke horn milled, polished
1/2" Aluminum open spacer port matched to manifold, exterior polished
Edelbrock Performer RPM, port matched, exterior polished with all extraneous castings and lettering removed
Homemade lifter valley splash shield to keep hot oil off manifold bottom
Camel hump 1.94/1.50 heads hogged out to 2.02/1.60, pocket ported, port matched, pump-friendly hardened seats, 3-angle valve job
Comp Cams 1.52:1 roller-tip rockers
Crane Cam Vintage Muscle 327/350 hp cam, 222 degrees @ 0.05, 0.447" lift (with 1.50 rockers)
Doug Thorley headers, dechromed and ceramic-coated
2.5" mandral-bent exhaust (including tips), 2" cross-over just before rear axle
DynoMax stainless Ultra Flow mufflers
Mallory Hyfire IV CD ignition box triggered off Accel points
Mallory high voltage chrome coil
Mallory spiral-wound coil wire
Mallory solid copper plug wires, ends soldered to wires
Champion plugs
37 degrees total ignition advance
Carter high volume fuel pump
Melling high volume oil pump
Open breathers
Polished aluminum high flow water pump
Flex fan with polished aluminum spacer
Polished aluminum one-wire 100 amp alternator
Muncie M-20 CR 4-speed
Hurst shifter
3.70:1 positraction
225/60/15 Firestone Firehawk SZ50s on 7”-wide Western 30-spoke Turbine Wheels

It's the little things that add up to the big picture and the secret to power is in the attention to details!

427V8

Ken
It's interesting what you say about positioning the rocker tip.
The mags all say to center the travel of the tip over the entire valve tip. This means at the highest loading ( full lift ) the tip is way over to one side of the valve.

But it seems like what you are saying, and it sounds good to me, is that at full lift the rocker tip should be as close to the center of the valve tip as possible to reduce side loading and thus valve guide wear??

bb69

Don't confuse full lift with highest load. The valve spring is obviously a large load, but accelerating the valvetrain is a huge load depending on the shape of the cam lobe and the RPM you are at. The contact patch starts at the edge of the valve tip furthest from the rocker, and as the rocker pivots, moves across the valve tip towards the edge closest to the pivot. You want the center of the contact patch to be directly over the tip when the load is the highest.

Keep in mind, that all this work is done with the OEM's for durability. Reduced friction means less heat, longer oil life, less wear, etc. For most guys, you might put 10,000 miles on your Vette in a good year. Many of us put on many fewer. The OEM's have to design for 150,000 miles. That number is a statistical mean as well, so many engine last longer than that. The differences we are talking about can be small, but make a huge difference over the life of the engine. No one is doubting that roller tips work. Just don't believe all the hype. Roller fulcrums serve to reduce friction (translating to higher HP at the wheels), but roller tips are for looks.

Ken