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Re: New tool steel Hemi rockers
[Re: dthemi]
#301793
04/30/09 10:51 AM
04/30/09 10:51 AM
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Joined: Jun 2008
Posts: 29
DOUBLE 0 AND HOLDING THREE
BottomBulbRacer
member
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member
Joined: Jun 2008
Posts: 29
DOUBLE 0 AND HOLDING THREE
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Quote:
Most of the big Fords we do have well over an inch of lift, brutal spring pressure and really fast ramps. The aluminums wear out after less than a season, even the Jesel stuff, so steel is a better option.
What kind of RPM are we talking here?
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Re: New tool steel Hemi rockers
[Re: polyspheric]
#301794
04/30/09 12:37 PM
04/30/09 12:37 PM
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Joined: Oct 2004
Posts: 3,097
back in Georgia
dthemi
OP
master
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OP
master
Joined: Oct 2004
Posts: 3,097
back in Georgia
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Quote:
with the right geometry, there SHOULD be very little side loading
The side load is a function of the difference in vectors between the valve stem and the pushrod, and it's not affected much by conventional geo errors.
the needle bearing could withstand more load than ball bearings
Definitely - how did they hide a big enough ball bearing in that support? The usual methods of replaceming a needle/roller with a ball requires one or more of the following:
1. larger housing for larger ball and larger bearing OD
2. smaller shaft for larger ball and same bearing OD
3. multiple bearings with same ID/OD on a longer shaft
If not, radial capacity is much lower.
First of all there is NO such thing as perfect Hemi geometry, it is unobtainable. You can make big improvements to it, but it is what it is and as a result they do side load. Side load reduction is just one small benefit, overall stability is the real focus and effect. As for the ball roller tech I won’t give up the guy’s technology of how it’s done, but it’s currently running in at least two of the fastest pro stock cars in the country, so I guess it a good thing no one has told them it won’t work. Also as I said before needle bearings are not intended to change directions like they do in a rocker. That’s not to say they won’t take it, just not the best application for them. These aren’t for everyone, but they are suited for all out class efforts.
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Re: New tool steel Hemi rockers
[Re: BottomBulbRacer]
#301795
04/30/09 02:28 PM
04/30/09 02:28 PM
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Joined: Oct 2004
Posts: 3,097
back in Georgia
dthemi
OP
master
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OP
master
Joined: Oct 2004
Posts: 3,097
back in Georgia
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Quote:
Quote:
Most of the big Fords we do have well over an inch of lift, brutal spring pressure and really fast ramps. The aluminums wear out after less than a season, even the Jesel stuff, so steel is a better option.
What kind of RPM are we talking here?
760-820CI Ford Hemis 8300-8700RPM sometimes higher in the traps.
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Re: New tool steel Hemi rockers
[Re: AndyF]
#301796
04/30/09 03:15 PM
04/30/09 03:15 PM
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Joined: Mar 2007
Posts: 993
Mid Michigan
Mr. Smurf
super stock
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super stock
Joined: Mar 2007
Posts: 993
Mid Michigan
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Quote:
Ball bearings is an interesting idea. I'd like to see how that was done. If there was enough space I'd probably design rocker with tapered roller bearings on each side of the rocker arm. Basically smaller versions of the wheel bearings used on a disc brake hub.
Good in theory but tapered roller brgs require a preload (the spindle nut). I think you would run out of width to fit it all in (if you get get the bearings small enough).
Ed
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Re: New tool steel Hemi rockers
[Re: Mr. Smurf]
#301797
04/30/09 08:06 PM
04/30/09 08:06 PM
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Joined: Oct 2007
Posts: 4,213
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,213
New York
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The "Timken" style (tapered roller) does control both radial and end thrust, but the bias devotes far more capacity to end thrust than is needed, resulting in a very large bearing compared to a conventional roller with the same radial capacity. Not an easy fit to the rocker stand.
What's strange is that the original rocker (long center cylinder with offset arms) removes most of the evil thrust effect by simple leverage: it's "submerged" by the length of the cylinder (if the cylinder were 3 feet long, the side thrust would be .0001 ounces).
Angling the rocker to align with the stem and pushrod reduces the obvious angle, but the far shorter center length simply increases the leverage, and therefore the thrust vector since the pushrod and stem till don't operate in the same plane. Not as much better as you might think.
Boffin Emeritus
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