H/S 1.5 rockers vs Ductile iron 1.5 rockers
#1832747
05/23/15 11:38 AM
05/23/15 11:38 AM
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carnut68
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Which ones would give you the best geometry with iron heads stock length valves? The H/S's seem to ride from the center to outside edge. RB/906 heads.
Last edited by carnut68; 05/23/15 11:49 AM.
America First!
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: carnut68]
#1832788
05/23/15 12:50 PM
05/23/15 12:50 PM
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Joined: Oct 2007
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polyspheric
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No way to tell without trying both. I just read Vizard's comparison of 20 different BBC rockers, and even the ones that looked really similar had really different lift vs. rotation patterns.
Boffin Emeritus
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: BSB67]
#1833029
05/23/15 11:58 PM
05/23/15 11:58 PM
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Joined: Jul 2013
Posts: 561 USA
B3RE
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mopar
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I think you are confusing alignment with geometry. That being said, I would guess that the ductile iron will be better for both.
Bingo! But, any of them can have correct valve side geometry. Just not "bolted on".
Mike Beachel
I didn't write the rules of math nor create the laws of physics, I am just bound by them.
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: carnut68]
#1833119
05/24/15 09:18 AM
05/24/15 09:18 AM
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Joined: Jun 2014
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carnut68
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Thanks for the input. I didn't do a very good job wording my question. BSB67 I have seen you running @PRP. I'm going to see if i can round up some crane or isky d i rockers then do a mock up.
America First!
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: carnut68]
#1833180
05/24/15 12:11 PM
05/24/15 12:11 PM
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Joined: Jul 2005
Posts: 1,954 Blairsden, CA
Triggerfish
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Which ones would give you the best geometry with iron heads stock length valves? The H/S's seem to ride from the center to outside edge. RB/906 heads. So Andy, are these Isky rockers a good choice for a 505" Indy head street stroker? Don't have a clue as to their ratio, but could send them to RAS if that's a good thing to do.
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: Cab_Burge]
#1833186
05/24/15 12:27 PM
05/24/15 12:27 PM
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Joined: Jul 2005
Posts: 1,954 Blairsden, CA
Triggerfish
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Thanks Cab, thought I was replying to Andy, but appreciate your info as always. Do you think these are a better choice than Crane rollers? I was thinking of selling them, but if they're a good choice, maybe I should use them. Got the matching pushrods, but they're for 906's. Thanks again for the info.
Last edited by Triggerfish; 05/24/15 12:29 PM. Reason: add info
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: Triggerfish]
#1833505
05/24/15 10:48 PM
05/24/15 10:48 PM
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Joined: Dec 2004
Posts: 10,612 Rittman Ohio
fourgearsavoy
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Those are the same rockers I have and I highly recommend getting them done at RAS if they still are doing it. I have their shafts and hardware too and it really is a bullet proof setup. Gus
64 Plymouth Savoy 493 Indy EZ's by Nick at Compu-Flow 5-Speed Richmond faceplate Liberty box Dana 60
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: carnut68]
#1833624
05/25/15 01:17 AM
05/25/15 01:17 AM
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Joined: Dec 2004
Posts: 10,612 Rittman Ohio
fourgearsavoy
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I had them bushed,blueprinted,oil redirected,bodies narrowed, new hardware,and thick wall hard chrome shafts for about $525.00 with shipping I thought it was a bit much until I got them on the engine and everything checked out perfectly. I really like how they fit the shaft and feel more precise when I set the lash. Gus
64 Plymouth Savoy 493 Indy EZ's by Nick at Compu-Flow 5-Speed Richmond faceplate Liberty box Dana 60
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: carnut68]
#1833986
05/25/15 04:34 PM
05/25/15 04:34 PM
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polyspheric
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It's a lot worse than you think (and I've been researching the subject for 40 years). Vizard compares rockers with the same nominal ratio for actual ratios at many different lift points, then the average lift. The results are nothing like what I expected with no pattern. In his opinion, high ratio right after IVO (to jump-start intake flow when the piston is nearly stalled and vacuum is low) is the most important, and it doesn't follow any metric that he discloses.
Last edited by polyspheric; 05/26/15 02:03 PM.
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: BSB67]
#1834537
05/26/15 02:04 PM
05/26/15 02:04 PM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
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Yes, ooppsss, thanks! Senior brain fade.
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Re: H/S 1.5 rockers vs Ductile iron 1.5 rockers
[Re: polyspheric]
#1834948
05/26/15 11:49 PM
05/26/15 11:49 PM
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BSB67
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In his opinion, high ratio right after IVO (to jump-start intake flow when the piston is nearly stalled and vacuum is low) is the most important, and it doesn't follow any metric that he discloses.
I would expect that from him....take advantage of the significant negative pressure from the open exhaust valve at overlap..... I would guess. So either mess with faster ratio, or change the rocker geometry to move the IV off the seat further per degree in overlap.
Last edited by BSB67; 05/26/15 11:55 PM.
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