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Old 04-14-2012, 01:57 PM
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which comp rockers on mild street engine?

As the title asks which comp cams rockers do you all think would be best for a mild 300+hp sbc?
The cam is a clevite performer cam 4.20/4.40 lift & there associated valve springs , which look to be pretty much stock replacements

the two im kinda torn between are

1: magnum1.52 roller tips



2: high energy 1.52 cast alloy full roller rockers.

I like the look of the high energy rockers as there in my budget & are full roller rockers so less friction/ cooler running etc - but as I understand alloy work hardens & I cant afford to grenade my motor.

the magnums are only roller tip so in my mind not as affective , but are steel so fatigue isn't an issue.

am I over thinking this , or should I consider just re using the original stamped items?
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Old 04-14-2012, 02:14 PM
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Quote:
Originally Posted by swompz
As the title asks which comp cams rockers do you all think would be best for a mild 300+hp sbc?
The cam is a clevite performer cam 4.20/4.40 lift & there associated valve springs , which look to be pretty much stock replacements

the two im kinda torn between are

1: magnum1.52 roller tips



2: high energy 1.52 cast alloy full roller rockers.

I like the look of the high energy rockers as there in my budget & are full roller rockers so less friction/ cooler running etc - but as I understand alloy work hardens & I cant afford to grenade my motor.

the magnums are only roller tip so in my mind not as affective , but are steel so fatigue isn't an issue.

am I over thinking this , or should I consider just re using the original stamped items?
For a mildly built street engine either are fine. The roller trunnion runs a lot cooler than the ball and socket, but that's only a concern when operating continuously above 5000 crank RPMs. Also, the aluminum isn't an issue with a street engine the spring stiffness is much reduced as are high RPM excisions so they just don't fatigue as they do with stiff springs and high revs. I've run a set of 1.6 Miller's on the street for about 10 years and 330,000 miles with no problems in an engine that dynoed when built at 420 horses.

As for a recommendation it's probably more let your finances be your guide. I like rollers but for a mild street engine they really aren't offering you anything but the look. Of course you cant see them. Gotta get some of that clear aluminum from Scotty to make rocker covers instead of space ship whale tanks, that would be cool.

Bogie
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Old 04-14-2012, 02:26 PM
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Originally Posted by oldbogie
For a mildly built street engine either are fine. The roller trunnion runs a lot cooler than the ball and socket, but that's only a concern when operating continuously above 5000 crank RPMs. Also, the aluminum isn't an issue with a street engine the spring stiffness is much reduced as are high RPM excisions so they just don't fatigue as they do with stiff springs and high revs. I've run a set of 1.6 Miller's on the street for about 10 years and 330,000 miles with no problems in an engine that dynoed when built at 420 horses.

As for a recommendation it's probably more let your finances be your guide. I like rollers but for a mild street engine they really aren't offering you anything but the look. Of course you cant see them. Gotta get some of that clear aluminum from Scotty to make rocker covers instead of space ship whale tanks, that would be cool.

Bogie

Thanks for your opinion on the matter. The only reason Im looking to change them is because Im currently building the engine & understand the original stamped rockers were not particularly accurate, & mine are going on for 30+ years old so couldn't hurt to replace them. as for cost both the comp rockers mentioned are within �5 difference hear in the UK. Im just trying to build the best spec/ long term reliability motor on my tight budget.
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Old 04-14-2012, 02:29 PM
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Quote:
Originally Posted by oldbogie
Gotta get some of that clear aluminum from Scotty to make rocker covers instead of space ship whale tanks, that would be cool.

Bogie
Remember these? On eBay right now, $695 buy it now price

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Old 04-14-2012, 02:35 PM
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Geeez Scotty must be raking it in selling these lol

I just had prw stainless roller rockers sudgested to me, but never heard of them, has anyone had expierience with these?

at a glance the look like cheep comp pro mag copies
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Old 04-14-2012, 02:37 PM
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Aluminum roller rockers are good because they are lighter, and thus allow more RPM's before they cause valve float. Many people have reported failure with aluminum so if you want a bullet proof motor aluminum is probably not the way to go. Some people who run aluminum rockers put screens and magnets in the oil drain holes in the heads. That way if a rocker decides to shuffle off this mortal coil it has a less chance of putting metal bits in the rest of your engine.

Steel/stainless roller rockers obviously are stronger than aluminum. There is a far less chance of grenading a rocker and thus your motor here. But they are more heavy and thus are going to induce valve float much sooner that aluminum.

Stamped rockers are the most long lasting and reliable. They are advertised as 1.5:1, but in reality when measured they are usually 1.45 or 1.46:1. They also tend to flex (more of an issue in performance engines and/or exotic cam profiles).

The horsepower benefits of a roller setup is not going to be seen at lower, moderate and daily driving street RPM levels. Obviously you will see less valve train wear and more oil life with rollers.

As far as ratios go, I would suggest sticking with 1.5:1. This will help keep your low end torque* (I assume that is what is going on with your mild 300HP motor). And also induce less pressure and stress on your cam (again I assume flat tappet, if you have a roller cam, then wear is not really an issue).

If you go to 1.52:1 that will increase the pressure on your cam lobes by about .9%. That doesn't sound like a lot but over a lifetime of use that extra pressure is just going to cause your cam to wear out sooner. 1.52 rockers will *probably* give you an extra 5-10HP on your 300+HP motor and shouldn't effect your low end torque too much.

1.6:1 rockers will increase lobe pressure by about 4% and I think standard thinking is you should never run 1.6 rockers on flat tappets because it will wipe your lobes. So if that extra 4% will destroy a flat tappet, then all of a sudden the 1.52 rockers at an extra .9% (which is about 1/4th the pressure) seems like a good reason to avoid.

I think my street engine goals are the same as yours. Reliability first, power later. So I would suggest getting steel, full rollers, and 1.5:1 (and go with screens and magnets if you are paranoid because a bearing could come unglued). If you only go roller tips you might as well just stick with stamped steel. Go all the way, or don't go at all. I know I would regret only going roller tips in the long run and it would grind on my mind.

Hope this helps,
~Dan

*Also keep in mind that cams are usually measured and degreed at .050" lift. So when you throw on some 1.52 or 1.6 rockers that means you will achieve that .050" lift sooner and the valves will close later, so bottom line, this also impacts your cam duration. This will impact horsepower, torque, and power band.

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Old 04-14-2012, 02:42 PM
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Quote:
Originally Posted by swompz
Geeez Scotty must be raking it in selling these lol
Holy crap...is this a "Star Trek IV: The Voyage Home" reference?
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Old 04-14-2012, 02:53 PM
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cheers dan, thats a good piece of insight

It looks like I have mis understood the rocker ratio side of things because I always thought 1.52.1 rockers were milder/ closer to stock than the 1.6.1 rockers.

& yes you are right on both accounts it is a flat tappet cam ,Im looking predominantly for a torque motor but still want some top end fun , as its being dropped in my little ford pop.
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Old 04-14-2012, 03:05 PM
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That is a sharp looking car! (I will overlook the Ford part!)

Also if you spend the money on high end roller rockers (which I would suggest), they are rebuildable, so they will last a life time. You get what you pay for and pay for what you get. At your power levels and if you don't get on the motor too much they will last a long time and you can probably forgo the screen/magnet business. Happy motoring!
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Old 04-14-2012, 03:17 PM
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im a sucker for old english tin.

well I genraly run the engine between 2.5 & 5k revs so do like to work it a bit.

not sure if I mis interpreted what you have said , but am I right in understanding im best staying with stock pressed rockers until I can afford som top end rockers, Or would the die cast comp offerings be reliable for my purposes?
sorry for seeming a lttle slow.
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Old 04-14-2012, 03:38 PM
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Yes you certainly can go stamped and upgrade as budget allows. You can even buy 8 a time and upgrade your intake rockers first, then exhaust later.

A few words of caution. I am not sure the condition or mileage on your heads, but stamped rockers can wear grooves into the studs. Fix that before you go roller. Stamped rockers also wear the valve stem tips. You might be able to switch to rollers without grinding them smooth if they are not too bad. Maybe someone else can chime in here. Also know that stamped rockers are self alinging. So you can buy self aligning rollers, or not. If you get standard rollers...not self aligning...then you need guide plates for the pushrods. I would suggest self aligning rollers personally as there will be no binding and wear on the pushrods.
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Old 04-14-2012, 03:46 PM
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It is also ill advised to use guide plates and self aligning rockers as that will usually bind the pushrods. So if you already have guide plates on the heads stay away from SA rockers.
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Old 04-14-2012, 04:06 PM
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Quote:
Originally Posted by Silver Surfer
Aluminum roller rockers are good because they are lighter, and thus allow more RPM's before they cause valve float. Many people have reported failure with aluminum so if you want a bullet proof motor aluminum is probably not the way to go. Some people who run aluminum rockers put screens and magnets in the oil drain holes in the heads. That way if a rocker decides to shuffle off this mortal coil it has a less chance of putting metal bits in the rest of your engine.

Steel/stainless roller rockers obviously are stronger than aluminum. There is a far less chance of grenading a rocker and thus your motor here. But they are more heavy and thus are going to induce valve float much sooner that aluminum.

Stamped rockers are the most long lasting and reliable. They are advertised as 1.5:1, but in reality when measured they are usually 1.45 or 1.46:1. They also tend to flex (more of an issue in performance engines and/or exotic cam profiles).

The horsepower benefits of a roller setup is not going to be seen at lower, moderate and daily driving street RPM levels. Obviously you will see less valve train wear and more oil life with rollers.

As far as ratios go, I would suggest sticking with 1.5:1. This will help keep your low end torque* (I assume that is what is going on with your mild 300HP motor). And also induce less pressure and stress on your cam (again I assume flat tappet, if you have a roller cam, then wear is not really an issue).

If you go to 1.52:1 that will increase the pressure on your cam lobes by about .9%. That doesn't sound like a lot but over a lifetime of use that extra pressure is just going to cause your cam to wear out sooner. 1.52 rockers will *probably* give you an extra 5-10HP on your 300+HP motor and shouldn't effect your low end torque too much.

1.6:1 rockers will increase lobe pressure by about 4% and I think standard thinking is you should never run 1.6 rockers on flat tappets because it will wipe your lobes. So if that extra 4% will destroy a flat tappet, then all of a sudden the 1.52 rockers at an extra .9% (which is about 1/4th the pressure) seems like a good reason to avoid.

I think my street engine goals are the same as yours. Reliability first, power later. So I would suggest getting steel, full rollers, and 1.5:1 (and go with screens and magnets if you are paranoid because a bearing could come unglued). If you only go roller tips you might as well just stick with stamped steel. Go all the way, or don't go at all. I know I would regret only going roller tips in the long run and it would grind on my mind.

Hope this helps,
~Dan

*Also keep in mind that cams are usually measured and degreed at .050" lift. So when you throw on some 1.52 or 1.6 rockers that means you will achieve that .050" lift sooner and the valves will close later, so bottom line, this also impacts your cam duration. This will impact horsepower, torque, and power band.
Not sure where some of this information is coming from, but I would suggest you do additional research...
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Old 04-14-2012, 04:18 PM
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This is info I have gleaned from here and other places. I am in the midst of researching rollers myself and this where I am at. I am certainly no expert. If you see errors then please share.
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Old 04-14-2012, 04:44 PM
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I just find some of that data out in left field, i.e. your "theory" about 1.5 vs 1.52 rockers, .9% pressure increase shortening the life of the cam, 1.52 increasing h.p. on a 300 horse build 5 to 10 h.p.? Certain rockers too heavy inducing valve float problems in a mild street motor like this? Questionable. I'm not calling you out, but cautioning the OP to do some additional research. I know more information is better than less, but whether it comes from here, another board or magazines doesn't necessarily mean it's accurate, fact or real life. JMO
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