Bone stock, ATK/Oreilly VC08, 350 Chevy, HEI Ignition. It makes a steady 17/18 in vacuum. Edelbrock 500 CFM on jegs dual plane manifold, no spacer (14/15 mpg hwy), factory flat tappet hydrolic lifter cam (so, smallish cam), TCI Street Rodder TH350, single exhaust plumed from iron rams horns with 2.5" full length.....so, mild and mid 70s factoryish. Call it a conservative 190 horse power. Currently has stock stamped steel rockers, probably rated 1.5 and actually less. Overall, runs great. I'm at the 5000 mile mark on this fresh engine. Figuring its time to pull torques on the engine and while im at it, adjust rocker arms. Was thinking of adding a bit of power that dosn't change the look and see ad copy that recommends roller rockers for smoother running, longer valve guide life, power/torque benefits at the mid range, no loss of vacuum, 1.6 is touted as best response on the smallish cam, etc. What do users think? Leave it alone? Stamped roller tip? Full roller? If roller, what ratio, a true 1.5 or just dive in at 1.6? Does a change to 1.6 ratio reduce vacuum? If roller, I'd like to avoid swapping valve covers, push rods, etc., does any of this stuff actually work with the associated factory components?
I wouldn't use cheap roller rockers in anything, when they fail the needle bearings kill everything. Stamped 1.6 rockers withOUT roller tips may be a good option for what you're trying to do. https://www.summitracing.com/parts/sum-g6801 Any roller tip rocker will require guide plates. I like these, quality, reliable good chance they will fit under existing rockers versus the big chunky aluminum versions. https://www.compcams.com/magnum-roller-rocker-arms-chevy-3-8-stud-1-6-ratio-1.html Roller tip rockers and guide plates, is about break even $ with a cam swap which would give the best return
I’ve heard on another board the narrow body Scorpions are good quality and priced right and fit fine under factory covers. No actual experience with them. One advantage I’ve heard about roller rockers is rocker to rocker consistently is better than factory stamped rockers as well as what you mentioned on the guides. I’d imagine they would free up a few HP as well. Im sure the extra HP offered by the extra lift can’t hurt either, would change a .450 lift to .480. For a piece of mind make sure your springs can take that much lift. Might be on the edge of what factory springs can handle.
I put many a night in stock cars pulling my SBC and BBC to 6500 RPMs with bone stock rockers, used ones at that. We ran cheater solid lifter cams, the HP was around 325 for the SBC and 375 for the BBC. The rules were no roller tips on the rockers, no roller rockers at all. On the 355 in my car, HP is around 425, I'm running Lunati aluminum roller rockers, another animal entirely.
Old school trick was use 289/302 Ford rockers on the exhaust valves and stockers on the intakes. Fords are 1.6:1. You have to be carefull about which ones you use, the earliest ones had guide rails on the valve end of the rocker and would hit the retainer. Using the ones from 1965 work best. (64 was the split year) As far as needing guide plates with rollers? The factory SBC uses the hole in the head as the guide so I don't see guide plates being a requirement. Guide plates require a lot of work that makes pulling the heads neccesary. Also, the rollers do take some of the friction out of the valvetrain, but you won't notice any difference in the way it runs unless you do change ratios. Then the improvement will be minimal, but will be an improvement.
I’ve never actually seen any data saying that they get a hp increase. If someone has it, I would be interested in seeing it. I think there is a lot of assumption that you get hp gains due to lower friction. I would love to see the data on a dyno. My thoughts are, people would be sorely disappointed for the money spent.
Don't think you'll ever realize any "seat of the pants" improvement. And that's what we're all after.
First step to wake it up is headers and dual exhaust...then put a bigger cam in it, and change the gearing/stall to work with the new cam.... If you just want to do something, for the sake of doing something, sure, you can put some different rockers in it. You're not going to notice a difference, unless they break, then you'll be cursing.
It's running fine. Adjust your tune and drive it everywhere. With minimal care your current setup will deliver a lifetime of memories.
A lot of the benefits of a roller rocker, such as increased guide life, is based on big cams that put a lot of strain on the valve train. You, at least at the moment, don't have any of that going on. And you seem more focused on smooth running and good vac numbers. At the performance level that you are at now I don't see you gaining anything using the roller rockers. In some circles it use to be popular on the SBC to run the 1.5 ratio rockers on the intake and 1.6 or 1.7 on the exhaust. But again that was trying to fine tune cams that were more robust than your current one. I would check it over and run as is and save the money. If you really want more performance, to do it correctly with a parts list that all works together you'll be pulling your new engine back apart.
Roller tip rockers don't do anything but make noise , full roller are a waste for a stock cam. Don't listen to the hype !
The one other thing they do well, is ruin your day when those cheapo offshore versions takes a s#/t in your new engine.
Much of the above about the use is correct. With stock performance parts, you'll gain nothing with roller rocker arms. If you were to go with a hotter cam, then it maybe beneficial to help the guides last a little longer, reduce some heat (stock arm combination has much more friction). In any case, for a street engine Steel or stainless steel rockers are the way to go. I've had excellent luck with Crower's, full roller rockers on the street on a couple of different engines. The roller tips can (AND DO !) pound out the the tips seat in the aluminum rocker arms. Then the more the tip slides back and forth, the "harder" it slams back and forth, until the roller tip try's to loosen its axle, then you really...have a problem. Many will say that they've never had a problem with "aluminum" rocker arms on the street. Why take the chance, just eliminate the possibility in the first place with a better material (stainless). Mike
I agree with the rest of the replies, on a stock engine and stock cam, there is little to be gained by going full or even roller tip rockers. The main advantage of roller tip is less scrubbing on the valve tip, which in theory has less force wearing the valve guide. The higher the lift, the more this scrubbing force becomes. On the 1.6 ratio vs 1.5, it should not have much effect on vacuum as the duration is the same, or at least for technical purposes, is so close as to be negligible increase. What is does help is overall breathing and it should make a little more power and torque since a little more flow. What you don't know, but is probably OK, is if the valve springs can handle the extra lift. Assuming a stock cam around 0.420 lift on 1.5 rockers, the 1.6 gives 6.7% more lift or using the 0.420 cam becomes a 0.448 lift. The other issue you might have is sufficient pushrod clearance in the head slot, as the 1.6 moves the pushrod just a small fraction closer to the rocker stud. Since the rocker and valve distance is fixed, the way to make 1.6 vs 1.5 is putting the pushrod point closer to the rocker fulcrum.
The optimal " sweep" of a rocker on a SBC with the geometry correct is 1/8" ( or less) , translate that to how much that rocker tip roller is actually rolling ( hint , just barely) plus the guide wear regardless of what rocker you run is immaterial .
It's looking like a solid consensus, not really needed/limited value at the performance level and don't risk turning a peach into a turd. Thanks fellas. I'll pull all the torques, double check rocker settings, change trans filter,, give it a tune and spend the rocker $$ on getting someone to wax the half acre of paint.
What 38Chevy454 said ^^^^^^ Personally I like roller rockers, but I'd get some decent ones. I'd go 1.6 or even 1.7 if your springs have enough travel to accomodate them. Then "IF" you ever decide to upgrade your cam you already have complimentary components in place. If you leave it alone, they still help with valve guide wear and probably get you to the "magic" 200 HP number.
I've been running the same set of Scorpion full rollers to 6500rpm for the past 14 years, but I've also got a pretty decent sized cam. On a mild cam engine you're not really going to see any improvement. Less valvetrain friction is always a good thing though.
Reposting the same link as above with a pic this time if you wanna try 1.6, this is the safest route. Agree pushrod slot clearance may be an issue. https://www.summitracing.com/parts/sum-g6801
Moving onto other parts that WILL give a real gain. Ignition curve, Full length Headers, cam swap (.450-.465 lift 214 to 224 duration at .050) is the range most street performance cams fall into, retain good vacuum, and don't need a stall converter or more gear. The 500 cfm carb will still feed it with a mild performance cam and have crisp low end.
I put a set of Comp Cams high tech roller rockers on my mid range cammed 355 when the first came out. I've put about 35-40 thousand trouble free miles on it since then. I did not notice any improved power or performance from them though.
Back in the eightys we would use 289/302 Ford rockers on both intake and exhaust valves on SBCs. My boss was a Ford guy, had a machine shop, and rebuilt all kinds of small and big block Ford engines. We could raid the take off parts bins and get what we wanted for a flat fee. The SBC is a 1.5 I think and the Windsor Fords are 1.6. I believe the studs were 3/8s. The improvements in performance were probably only in our heads. We also ran the CompCams roller tip rockers foe 289/302 on our SBCs. Same results - improvements in performance were probably only in our heads. If your truly asking for opinions leave the rockers "as is" and do a mild cam swap. You will notice a change in operation and performance from a well chosen mild camshaft.
If his engine is a " smogger" motor , the one purchase that would help it most IMO is a good set of heads , get some reasonable flow ,& raise the compression !
You will see no seat of the pants gain with roller rockers. Stamped ones are exactly what you need in your current set up. I have used the comp roller tip rockers in the past just because I didn’t have any good original GM stamped rockers. If you have aftermarket stamped rockers, get some new GM ones or good used GM ones. The aftermarket ones are garbage. They love to break the ball seat right out of them and then you have the chance of tossing a lifter out of the bore or bending a push rod. Also, if you have a hydraulic cam there should be no readjustment needed on them. That is the purpose of a hydraulic cam, less maintenance. By all means check them, but be wary of adjusting much at all. If it very loose or making noise you have a bigger problem (collapsed lifter, cam love wiping )Get them too tight and that new cam will have flat lobes before you know it.
I've used Crower stamped roller tip rockers on my last 3 builds. I like them better than the full rollers with all the needle bearings, and they clear stock height rockers, even with poly locks. I've got about 20,000 miles on a SBC now with them, and just put another set on my latest build. Be sure to check pushrod length if you decide to change to 1.6 ratio rockers, as you may need to change pushrods also if the 1.6 ratio wont run centered on the valve stems with the pushrods you have now.
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