Full Roller Rockers - More DEP Bashing
 

Hey DEP ole' buddy. You know you love this!

I was at a car show on the weekend and, among other things, spent some time looking at the various crate motors on display. I'm kind of partial to the 502 big block, but that's fodder for another post.

Now I'll start by saying that the people manning the posts were either sales people, their wives or their mistresses. I asked one what made a smog legal 350 (245 fhp) smog legal and all I got was a brochure on how to order one.

One thing that I did note was that every single solitary engine from the smog legal 350 to the biggest big block had full roller rockers. No exceptions. Granted most were extruded aluminum versions and in pretty colors so they made for a nice display, but all of the build sheets had these written in as well.

Part of the reason that I post here is that, after agreeing that full rollers probably weren't worth the added cost in DEP's post and in Page's as well, I went ahead and bought a set from a forum member. I'm still working on rationalizing the cost (they are very cool though :cool: ).

The other part of the reason that I post is that these builders are very conscious of costs and more so about their output numbers. If these were not worth the money on a 245 HP mouse, then why would they bother?

:lurk:

Rational? Who's rational? If we had any sense, we wouldn't be driving 25+ year old cars...or should I say money pits!

If full rollers make you happy, that's what counts! :cool:

the smog legal 350.........is that the Goodwrench 350 for $1400?

I don't know how they could afford to put a set of full rollers for that price.

the thing that makes it smog legal is the cheapo mild cam with the wide lobe separation angle.


Now i've heard that needle bearing rollers reduce the oil temperature by 20 degrees. That would come in handy if you participate in HPDE events.

Display motors...I think that says it all. They install what customers want to buy or whatever is "expected" on the motors....not necessarily what is BEST for it. Not saying roller rockers would HURT performance, they'd just hurt your pocketbook. :)

For your car...like Page says, whatever floats your boat.

In answer to turtle's question...GOOD question. I suspect the answer is the little stamp you see on the side of the rocker. "Made in (list your favorite 3rd world country)".

Dep

DEP,

That was a disapoointing response. I go through the effort of goading you and what do I get?

It may be as simple as a couple of you have said. Display engines. I particularly liked the purple ones.

Turtle, I don't think that this one was that cheap. I thought it was a little over $2k. Could be the cam, but I would at least have expected an EGR.

I thought I saw similar stats in one of the tests done with roller rockers in Hot Rod a few years back. :)

I'm sorry. After reading thousands of posts about "I'm instaslling a 383 Roadrunner engine and I need help", I get kinda worn out :D

Dep

The only time true rollers are needed is when spring pressure exceeds 300 lbs seat. This is only needed when a roller cam with higher lifts is used. They are not needed anywhere else. Cheap rollers are just that and probably will not last to long and could break under some heavy spring pressure. Check out some of the books on valve trains and they will and have tested what rockers (roller and stamped and roller tip) are good and how much pressure they can take before breaking. If you want to spend your money on rollers I would say it is not wasted but it will add no more power than a set of the same ratio standard rockers. :cheers:

well i put a set of comp pro magnums in my 327 hyd flat tappet cam engine that i built and i bought a set of isky roller rockers for my blown BBC solid roller engine that i am building . maybe i wasted money on one and not the other, or on both or niether but what the hell. i'll FEEL like it runs faster. as a medical guy i can assure you some people in research trials feel better after getting a placebo. so what, feeling better is feeling better.feeling faster in the SBC which will probably never see a track is just as good as being faster :) as for the BBC well who am i to buck everybody.

Guys,
My last job was at a company that made valvetrain components for all the car companies, from VW to Porsche to Ford to GM. We didn't guess about these things, we did the analysis and testing. One of our biggest components was rockers, both the type used in pushrod engines and overhead cam engines. I can tell you for sure that roller TRUNNIONS have much less friction than the original equipment rockers without roller trunnions. As for the tips, a properly designed tip has a larger diameter and crown than a roller tipped rocker. The result is higher contact pressure, and resulting friction and wear, than a non-roller tip. We also supplied many of the aftermarket companies with trunnion bearings. The equipment required to pump out that many needle bearings is too cost prohibitive for most companies. So, say what you want, but a roller trunnion creates less friction, and therefore absorbs less HP. The roller tips are for looks.

Ken

I'll agree to a point on that. It does reduce the friction but how much HP is gained on a 300 HP engine? 1 or 2 HP. It will reduce the oil temps slightly but how much. On an endurance engine I could see this, but most of the street engines are running 1500 to 2500 rpm and the oil temps never get high enough to worry about.
If the roller on the tip does nothing than why do the full roller rockers have a roller tip. If the large diameter is better than the roller why would you go to the extra cost of putting an expensive roller on the tip?

GM used roller rockers on the LT-4 engines did they not???? they should help prevent valve guide wear cause by the side loading of the stock non roller tip rockers if you got to a cam with more lift than the stock chevy cam because of the geometry change. if you are using low pressure valve springs the heat is not a problem but if you go to after market springs the oil temp can change 20 degrees

Guys for stock or mild buildups you don't need them, won't hurt of course unless they are cheap aluminum Chinese and they fall apart.

For high lift cams ( over .550" lift) and high spring rates ( over 350# open ) I would definatly put them on the motor :D

What kind of rockers does GM put on the LS2s and LS7s??

Brett

I can't offer any proof on how much hp is saved by the reduced friction. There are a bunch of roller rockers to choose from that costly slighly more than $100 over standard rockers. If it were 1 or 2 horsepower, it may not be the best dollar spent for performance. If there is a savings of 5 hp, then that changes things quite a bit. That comes down to $20 per horsepower. Spending $1000 for a set of heads that yeild 30 hp equates to over $30 per horsepower. Why is it that people are quick to recommend heads but then say roller rockers are a waste?

I am also wondering the potential power that can be gained with roller rockers. These seem to have potential though. http://www.cranecams.com/?show=techarticle&id=4
There was a guy that did back to back dyno testing with these for the ls1 engine, and he gained somewhere around 10rwhp.

If you look at the GM small blocks, you will see roller trunnions and plain tips. The tip is designed so it contacts the valve slightly offset. This induces some rotation in the valve to help even wear on the valve.

They make rockers with roller tips because people buy them. If you guys knew how cheap it was to make a rocker arm at high volume numbers, you would be amazed. I believe we were approaching a billion needles a year when I left the company. Even a set of arms that cost only a $100, I would say less than half of that is manufacturing cost. A large part of aftermarket parts is packaging, distribution, and marketing. Throwing in a roller tip is not that much more, but the company can charge more.

Also, keep in mind that we were designing for original equipment engines. That means 150,000 miles of durability. Most of the OEM's run dyno tests with the engine at peak HP for hundreds of hours straight. Under those conditions, every bit of saved friction counts.

:lurk:

BTW....we already had the discussion about rollers than cost $100 more than stamped rockers. Be prepared to fish for bits of aluminum pieces if you use them. Crane "shiny gold" rockers are probably the best aluminum rockers and they are 4 times more than stamped rockers.

If I had to use roller rockers, I'd go with stainless steel versions. Slightly heavier than aluminum, but much less susceptible to fatigue.
They also cost MORE than aluminum rockers.

Note that the hot big block cams from Chevy were more than .550 lift and STILL used stamped rockers.

Dep

I bought an off brand of shaft rocker for 280 bucks. Figured I would give a little guy some money. Sometimes the little guy can be quite good, and trying to compete with Name brands.

Besides I am not exactly gonna be running a crazy engine.