racerx520

iTrader: (1)

hey guys, i am certain this has been beaten to death, but i'm looking for some guidance with some stuff i cant seem to find when doing a search.

i have summit racing aluminum heads with max valve lift of .480 and crane 2032 cam with duration at 270 int./276 exh and lift at 0.452 int./0.465 exh (factory rocker). I am looking at getting some new rockers since i'm bit with the horsepower bug and was curious what everyone was thinking. One person told me they think that a full roller might fail with street use, however I want to get the most out of the car that i can. looking to hopefully do some 1.6 rockers and the car is a weekend car at best. thanks everyone!

GeneralDisorder

iTrader: (1)

Roller tip on it's own does virtually nothing. All the performance gain is in the trunion bearing. Any high lift engine will benefit immensely from full roller - in fact non-roller rockers may be contra-indicated due to lift. They can get so hot it will carbonize the oil around the stud and ball/socket. That's a LOT of friction. More lift = more friction. With near 1/2" lift you will probably lose 20+ HP and increase your oil temps by tens of degrees if you DON'T run full roller rockers.

If you buy quality rockers such as Scorpion, etc, and set them up correctly, failure is unlikely.

GD

Jorlain

iTrader: (4)

https://www.motortrendondemand.com/d...er/0_bhpycxdw/

skinny z

If David Vizard counts for anything, his budget builds have emphasized the roller tip rather than the full roller. But you have to put that into perspective. Those builds in his popular books are generally budget orientated drag racing engines for the most part. Engines that spec well on the dyno and will produce power. But I think it's fair to say that if longevity I.e. street use, is of any concern, budget notwithstanding, the full roller is the clear choice. I think even Vizard would agree.

EDIT: And if he doesn't I'd be more than happy to hear his point of view.

GeneralDisorder

iTrader: (1)

I don't see how friction ball/socket vs. needle bearing ends with friction socket winning. That's crazy talk.

GD

skinny z

With respect to Vizard, his Maximum Performance SBC on a Budget books are not coincidentally, about the budget. Guess if you were to analyze on a HP produced per dollar invested, the margin goes to the roller tip. But as I mentioned, that doesn't necessarily transfer to Hp per Dollar per Mile Driven.
I'm full roller all the way.

GeneralDisorder

iTrader: (1)

Quality full rollers ain't cheap. Neither are roller cams or roller lifters. But also not something I would throw out due to budget constraints. I mean.... IMHO small blocks prior to roller cams are dead to me.

I mean if budget drag racing is all you are after..... A used Vortec, open up the ring gaps, and spray it into low earth orbit. Whrn you drive over the crank.... rinse and repeat. LoL.

GD

Vader

Obviously, that one person doesn't know about the literally millions of factory full-roller rocker arms on GM vehicles which have been there for well over 20 years. I know the tip isn't rollerized on the V-6 engines, but that should put to bed the questions about the roller trunions.

I guess (technically) that person could be right, and after about 600,000 miles of street use they might fail.

mrestrictrplate

iTrader: (2)

Run a good brand full roller(around $200 for comp cams if you shop). Street driven that all my life, no problems...done

ironwill

Simple engineering basics would indicate that a roller bearing is superior in every way to a ball/socket bearing. IMO, reported "failures" of roller rockers on street engines are largely caused by 1) cheap, off-shore rockers and/or 2) incorrect installation resulting in poor geometry.

Buy American-made, name-brand engine parts and follow the manufacturers' checking/installation instructions to the letter.

racerx520

iTrader: (1)

thanks guys for all the info! definitely going to wind up buying full rollers. was looking at these ones since summit usually has good re-badged stuff at a lower price:
https://www.summitracing.com/parts/sum-g6936-16

I'm sure its a dumb question, but what about the pushrod length? would that have to be increased or is using the stock length ok?
I'd like to increase the rocker ratio to 1.6, but would that necessarily be possible with the setup i have listed?

ironwill

You'd do well to stick with rockers made by your cam manufacturer.

Pushrod length is one of the factors involved in checking/correcting valve train geometry. The rocker manufacturer should be able to provide you with detailed, step-by-step instructions on how to properly set up your valve train. Even on an engine that has never been decked or the heads milled, 'stock-length' pushrods may prove to be wrong for your particular setup.

As far as increasing the rocker ratio, valve-to-piston clearance might be an issue. Again, this is something that would have to be checked.

racerx520

iTrader: (1)

thank you very much for the info!

ploegi

Also something to pay attention too, is going to a higher ratio rocker, going to exceed your valve springs max lift??

dmccain

iTrader: (2)

Theres a reason GM has put full roller rockers on millions and those engines have stayed together.

racerx520

iTrader: (1)

I believe it will, according to summit, different springs will increase the lift. not sure if putting the extra money into it is worth it, or just stick with 1.5's

newbvetteguy

+1 on what everyone else has said re roller rockers.

Another thing to think about is aluminum vs. steel; aluminum DOES have a maximum fatigue life AND your engine is at stake if you go with Chinese rockers. (Not a place I'm comfortable going with Chinese)

I totally agree with going with 1.6 ratio rockers on the intake side assuming you have the clearance on your heads, and assuming your springs can deal with the added lift as someone else already said. The ratio change would move your max intake valve lift to: 0.482". You might consider buying a set of 8 1.6 ratio rockers for your intake side and a set of 8 1.5 ratio rockers for the exhaust side as your cam having more lift on the exhaust side is kinda of an older design and the more modern thinking for N/A engines is actually LESS lift on the exhaust side, especially as you have the added duration on the exhaust side already.

Comp has engineered their "CompCams Ultra Pro Magnum" steel rockers to have the strength and longevity benefits of steel with most of the weight / moment-of-inertia benefits of aluminum rockers; and right now at Jegs you can get them for only $21 more than those aluminum Summit ones you were looking at: https://www.jegs.com/i/COMP-Cams/249/1602-16/10002/-1 ($20 off sale right now)

If you're buying new rockers, you might consider upgrading to 7/16" rocker studs vs. the floppy 3/8" studs -rockers made for 7/16" studs are identically priced; you just have to pay $24 for the new, bigger studs. https://www.jegs.com/i/Speedmaster/7...6%20Components -With the typical RPM peaks of a TPI thirdgen, it might be overkill, though.

Add the CompCams "High-Tech" adjustable pushrod length checker tool to your order so you can check for the ideal pushrod length. To check for length follow the super easy steps from Chris Straub / Scott Foxwell. The Comp Ultra Pro Magnum trunions are huge and to get the geometry right (line between center of trunion and roller bearing at a 90 degree angle to the surface of the head @ Mid valve lift) you'll have to move it up higher on the stud than your current rockers probably sit. -You can try your current pushrods first and see what the sweep pattern looks like but I bet they're too short. -Opportunity to upgrade to thicker wall pushrods! -Christmas in May!

Rocker Geometry Process: Just unscrew the checker pushrod until you get the length right per the video above -then count the number of turns of the adjustable pushrod to get it back down to the stock length -take stock length (6.8") and add 0.005" for every revolution of the pushrod length checker. (I just did this all 3 weekends ago so it's all fresh in my mind.)

Adam

newbvetteguy

If your springs can deal with it, the performance benefits are definitely worth changing to the 1.6 ratio on the intake side. (You need to make sure the extra movement of the pushrod isn't going to bind in the head pushrod holes or the valve guides (unlikely).
The ratio swap not just gets you a bit more max lift, but it keeps the valve at higher lifts for more time and gives you a TINY increase in duration at higher lifts, too. (Which is why people see a slight increase in their HP RPM Peak when switching to 1.6 ratio rockers) -The seat-to-seat durations are unchanged so there's no loss in low-end torque like there is when you go with a bigger cam, either.

If your heads flow more between your old lift and your new lift, the benefits are more significant but even if the ports' have hit their max CFM flow at your previous valve lift, you'll likely see gains from keeping the valve in the "good air" longer.


Adam

427seven

Right on, the explanation doesn't get any more clear than this......

RJ IROC

A tip I found when I was putting my engine together. It's stupid easy to make an adjustable length pushrod, instead of buying a "high tech" one. You can take an old pushrod, cut it, remove 1/4" of length from one of the cut ends, and tap the cut ends to a #10-32. I didn't even drill it before tapping. Take some 10-32 threaded rod, thread it in one side, twist on a couple of nuts, and thread it into the other side of the pushrod. Voila, an adjustable pushrod. Set the geometry, remove the pushrod, and measure it. You'll need a larger set of calipers, or use a drop gauge...etc. to measure the length. Once you get your length, order the correct pushrods.

skinny z

Keep in mind though that not all manufacturers measure their pushrods the same way. You'd think that it would be tip to tip in all cases but that's not necessarily so. Its easy to be off my a significant amount if that detail is overlooked.
I use Comps adjustable pushrod and their pushrods so there's no second guessing.

racerx520

iTrader: (1)

Thanks for all the help guys, I emailed SummitRacing and got this response back after a bit:

"Below would be the rocker arm options, both 1.5 and 1.6. Springs would have to be changed for 1.6 ratio as well as the push rods. Clearance in the push rod guide hole in the head must also be verified. There may no gains using the 1.6 ratio rocker arm. The fuel has to be re-calibrated and it will not alter the duration of the motor. The gain would be the stabilization of the valve train based on the rocker arm material. I never advise changing ratios unless specifically recommend by the cam manufacture based on use."

So with that, I think i'll wind up going with the 1.5 full rollers from Crane Cams just to keep with the same parts as the cam.

skinny z

Remember that any change in the rocker arms, regardless of ratio, will require an assessment of the valve train geometry. There could be considerable differences between the stockers and the aftermarket arms.

Jorlain

iTrader: (4)

Also, take what Summit says with a grain of salt. Their customer support people are not necessarily engine builders or designers, which is why they'll always recommend what's on the cam card. Increasing the ratio effectively increases lift and duration, making the cam "bigger" in a sense. Sometimes you only want to add to intake, sometimes only exhaust, and sometimes both. Like anything else, it's a tool for tuning.