Roller Rockers

[Ole Blue 68]

I'm running 487 heads right now and was looking at switching over to roller rockers since it seems to me to be a fairly cheap way to get a couple of extra horses. So I have two questions:

1) Is the swap worth it?

2) Can I get away with my stock springs or should I look at upgrading those too?

[Billla]

Roller *tip* rockers have been shown to add a few (3-5) HP at the very top end, but IMHO this is due more to the stiffness and fulcrum location of the arm vs. any benefit from the roller tip. CompCams claims 15-20HP increase (but does not provide a dyno chart) - I'll just note those must have been some lousy stamped steel arms

Full rollers provide NO benefits below 6000 RPM; everybody gets into the "less friction" school of thought when it's really about valvetrain stiffness. On a stocker, it's a waste of time and money - they also likely won't fit under your existing rocker covers.

There are better ways to find horsepower You could consider going to 1.6 rockers (Crane and CompCams make stamped-steel sets for about $90) for an increase in lift and duration if your heads are up to it.

[Ole Blue 68]

Thanks for the good info Billla, I should have mentioned in my first post that I was gonna go with 1.6 roller tips so I'd reduce the "friction" and also get some more lift.

[Billla]

No worries - it ain't gonna reduce friction, but the extra lift/duraton is worth thinking about. It's a pretty minor improvement if any - again, I'd see elsewhere but it's your dime

When moving from 1.5 - 1.6:
- Multiply 1.5 lift by 1.067
- Every .1 increase in ratio increases duration by ~2 degrees
- Be SURE your springs are up to it; check for coil bind and rocker bind carefully.
- No value unless the heads will flow to that level of lift.

[Ole Blue 68]

Originally Posted by Billla

- Be SURE your springs are up to it; check for coil bind and rocker bind carefully.
- No value unless the heads will flow to that level of lift.

Well I think this rules it out then. I was hoping to get away without changing/upgrading the springs and I'm not sure how much more flow I can get out of stock 487 heads..

[lyrikz]

billa, you have a PM

[SRH916]

Sorry to steal this, but in my truck there is a stock goodwrench 350 the 250 horse version. would 1.6 rockers work? the engine has about 1500 miles on it now.

[Pyrotechnic]

Be careful with cheap roller tip, or full roller rockers. If the pin slides out and the roller tip comes off, the rocker pops out your keepers and the valve drops down into the cylinder and you blow your motor. It's really just the cheap chinese junk where this is an issue. Stick with quality name brands. If anything, I consider a set of stock rockers superior to cheapo roller tips in any situation where reliability is important.

Crane cams also has 1.5 and 1.6 stamped rockers that are supposedly a little better than stock.

[Ole Blue 68]

These are the ones I was looking at...

http://www.jegs.com/i/Crane/270/11746-16/10002/-1

[Pyrotechnic]

Those look alright. Most name brands are good, just depends how much you want to spend.

[Billla]

Originally Posted by SRH916

stock goodwrench 350 the 250 horse version. would 1.6 rockers work?

Work as in fit and not break anything, yes. Work as in provide any performance benefit, not really. There might be a couple of ponies there, but not many.

The cam is intentionally very mild (P/N 12364051) with .383/.401 lift, 194/202 duration and with a 112 LSA. This is a low-end torque cam, plain and simple, and made to be run with stock exhaust manifolds. Moving to 1.6 rockers makes the cam .408/.428 with 196/204 duration - still pretty mild and the lift is beyond the point where the head flow levels out. The heads are P/N 93438649 with 1.94/1.5 valves and intake/exhaust flow that tops out around .400 with 204I/143E CFM.

That being said, the difference between the 260 and 290 is the cam - P/N 3896962 for the 290 which uses P/N 3896962 with .450/.460 lift and 222/222 duration. IMHO the power is coming more from the single-pattern,longer duration and the expectation that the 290 is used with headers...but the heads are still the limiting factor.

How's that for a really long answer to a really short question?

[SRH916]

Thanks for the explanation.

Still a tiny bit confused, let me see if I got it right, the heads are a choke point here?

[Billla]

Originally Posted by SRH916

Still a tiny bit confused, let me see if I got it right, the heads are a choke point here?

Yep, as noted in my post "the heads are still the limiting factor".

Bottom line is that it doesn't do any good to have more lift than the head will flow - if flow tops out at .400, then going much beyond that doesn't buy much. We can add duration to make up for topping out the flow (leaving the valves open LONGER since it doesn't do any good to open them FURTHER, but that diminishes pretty quick as well and since it typically comes with more overlap there are some sacrifices in driveability and fuel economy - more than you'd typically see for a properly designed engine making the same power levels. Once you hit the wall on the cam, upgrading the heads is the only real option.

Swap some Vortecs onto that 250 horse with a cam upgrade and headers and you're into 325+ HP...

[SRH916]

What would you reccomend for a cam? sorry for hijacking :\

[Billla]

Originally Posted by SRH916

What would you reccomend for a cam? sorry for hijacking :

As long as the OP is OK we're OK.

IMHO, I wouldn't bother with a cam upgrade - the stock cam is pretty close to the max lift flow of the heads. I'd just drive it It'd take a head/cam swap to actually make significantly more power.

[70rs/ss]

Power is mostly head and cam, compression helps but not if the heads suck. An engine is just a fancy air pump, air in through the carb (too small crappy flow too big no velocity) intake is the next restriction, good dual plane more flow, heads, flow lots of air (too much lose velocity, too small restriction). Exhaust to get the air back out. If you look at it that way, you begin to see just changing rockers or a cam will only benifit you if the rest of the components work together. I like Vortec heads set up for more lift, bigger cam, roller rockers (because they also sve wearing out the stems and guides) RPM air Gap, headers. Nothing huge, just a good complimentary group of parts that'll work together.

[Billla]

Originally Posted by 70rs/ss

roller rockers (because they also sve wearing out the stems and guides)

I haven't seen any issues with stamped-steel rockers and guide wear - if there's a side load, then something is set up wrong and...as noted...it's not about friction (which would also induce fore-aft loading).

We'll agree to disagree

[SRH916]

Well, I shouldn't have any problem porting the heads and getting some bigger valves 2.02/1.60 since I was an intern at a machine shop here. Probably wont cost me more than parts and my time. So if I were to pocket port the heads, and go for the bigger valves, would the 1.6 rockers help?

[Billla]

We're getting into a really subjective area at this point.

IMHO, putting bigger valves into these heads typically isn't a good investment - but if you can cut the seats/throats, sweep the chambers and get the valves/springs for cheap you might be in a different position. Looking at these in the past, there was definitely room for cleanup on the short radius and the boss...so if you have the time and know where to cut, then go to it. A little detail work can make a HUGE difference. If the shop has a flow bench, I'd be REALLY interested in seeing what you could get out of the heads.

The challenge then becomes making use of the flow - and the 1.6's would be a minor change; it'd be time for a different cam.

Sorry - I feel like I keep putting up roadblocks and I'm not trying to at all.

[70c10]

Originally Posted by Ole Blue 68

These are the ones I was looking at...

http://www.jegs.com/i/Crane/270/11746-16/10002/-1

You should check ebay. I just bought those exact rockers with lock nuts for $110 shipped to my door!

[SRH916]

No, its ok. Its really good to learn about this. It would be alot worse to end up buying something that wont help me, especially on the budget im on.

[Ole Blue 68]

Originally Posted by 70c10

You should check ebay. I just bought those exact rockers with lock nuts for $110 shipped to my door!

New? If so that was a great score!

[70c10]

Yep, brand new sealed package

[70rs/ss]

Billa, there is some friction as the solid tip of the rocker slides across the vave tip. This is the cause of guide wear over time as well as wear to the valve tip itself. I do not think a roller rocker is a 10, 15, or 20hp gain, but in conjunction with the roller cam, etc, etc it is a piece of the puzzle. As for big valves in the Head, I'd probably hunt down a set of Vortecs before I reworked another factory iron head, they just flow and work that much better (really once you get a set of modified Vortecs, {purchased from Summit or the like} you end up having $8-900 in a set of iron heads) and a Summit brand aluminum head only costs $900ish and comes with 2.02/1.60 valves. I like the stock head with a differnet spring to allow more lift, but beyond that I would get a set of aftermarket heads, as you put more $$$ into the Vortecs, aftermarkets come into the price range and offer more options. It is all a matter of what you want, if the parts and labor are not too high then you may be able to rework a used set of Vortecs and get what you want without breaking the bank. Without a flowbench you are kinda working in the dark and may actually hurt flow. As Billa said open up the throat and seats, and Backcutting to actually allow the bigger valve to improve the flow. I really don't think a 2.02 1.60 has a lot to offer on anything but a high RPM motor, or a big inch SBC. 1.6 rockers are a crutch to improve cam lift without swapping in a new cam. 6 of one and half dozen of the other, if a new cam is part of the plan just get the cam size you want and stick with a 1.5. I think Billa and I agree, I just like to add better parts as I can. Roller rockers are not a magic bullet, but along with a laundry list of other parts they can offer longevity, a little more power and allow for more peddle response with roller cam, better heads, etc, etc.

[Billla]

Originally Posted by 70rs/ss

Billa, there is some friction as the solid tip of the rocker slides across the vave tip. This is the cause of guide wear over time as well as the vale tip. I do not think a roller rocker is a 10, 15, or 20hp gain, but in conjunction with the roller cam, etc, etc it is a piece of the puzzle. As for big valves in the Head, I'd probably hunt down a set of Vortecs before I reworked another factory iron head, they just flow and work that much better. Without a flowbench you are kinda working in the dark and may actually hurt flow. As Billa said open up the throat and seats, and Backcutting to actually allow the bigger valve to improve the flow. I really don't think a 2.02 1.60 has a lot to offer on anything but a high RPM motor, or a big inch SBC. 1.6 rockers are a crutch to improve cam lift without swapping in a new cam. 6 of one and half dozen of the other, if a new cam is part of the plan just get the cam size you want and stick with a 1.5. I think Billa and I agree, I just like to add better parts as I can. Roller rockers are not a magic bullet, but along with a laundry list of other parts they can offer longevity, a little more power and allow for more peddle response with roller cam, better heads, etc, etc.

We'll have to agree to disagree. Roller "tip" rockers generally don't roll at speed (although high quality full rollers do)...they slide on the oil film just like the stamped steel ones do. I've observed this personally

Remember that while stock iron guides are a wear item on the SBC, they go 60-80K miles or more with stamped steel rockers - and bronze guides are even less wear-sensitive. So I don't see 80-100K as being a longevity problem . For the engines I dissasemble I rarely see any significant wear at the valve stem tip if the engine was well cared for. My comments are based on 150+ performance overhauls over the years - we'll just recognize we've had different experiences and so make different recommendations.

The blanket statement that 1.6 rockers are a "crutch" I'd also disagree with. The higher rocker ratio also opens the valves faster (faster ramp) so in the right situation there are other benefits.

Pocket porting is generally safe if it doesn't go too far - working the throat and short radius will always improve flow. Going further, that's not the case.

Don't want to star a shoot-off, I just have different experience here. I see a lot of folks bolting on expensive race-only parts on the street with NO value and it offends my budget sensibilities - power costs money, and I like to see money directly turning into more power.