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| Durango_Boy | Debating Rocker Ratio. | ||
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Elite Guru
 
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The roller rockers I have for my roller 405 are roller tipped stamped rockers, 1.5:1 ratio. I wondering though, with this cam, would 1.6:1 ratio rockers be of ANY advantage, and would they bring any new issues to the table or not. I'm wanting to replace the rockers I have with full roller rockers to reduce that drag even more.
Here's the cam I have slated for purchase when I have more cash. http://cgi.ebay.com/ebaymotors/ws/eBa ... EWAX:IT&item=200327770457 |
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Posted on: 2009/4/20 12:34
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| 400hp427vette | Re: Debating Rocker Ratio. | ||
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Senior Guru
 
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Do you have aftermarket heads? because most stock cast iron heads do not have the pushrod clearance for 1.6 rockers other issue could be valve clearance 1.6 rockers would make the valve lift 554/576. Other than that you should be good to go.
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Posted on: 2009/4/20 18:14
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| Durango_Boy | Re: Debating Rocker Ratio. | ||
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The heads are after market aluminum Vortec heads so I doubt there would be much of a push rod clearance problem, and if there was it would be easy to remedy.
My springs are rated up to .600" so the extra lift isn't a problem either. Are there any actual benefits other than the extra lift? |
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Posted on: 2009/4/20 18:29
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| 400hp427vette | Re: Debating Rocker Ratio. | ||
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I am not sure about how it would effect low rpm torque but high rpm hp is the only thing that I know of.
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Posted on: 2009/4/21 2:20
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| dstaley | Re: Debating Rocker Ratio. | ||
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Guru
 
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If it helps any, I ran extensive simulations on my 409 SBC and found very little benefit to 1.6 ratio rocker arms. I was using engine analyzer plus. My combination is limited by the intake manifold (Performer AirGap, non-RPM) and no additional lift or duration will help.
I'm betting that if you're using the same manifold design (and I think you were) you'll find yourself in the same position. |
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Posted on: 2009/5/7 3:08
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| Durango_Boy | Re: Debating Rocker Ratio. | ||
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Elite Guru
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Quote:
Yeah from what I understand, they would really only help in the upper RPMs and with an engine and cam like I have even that would be limited. |
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Posted on: 2009/5/7 22:08
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| Dantana | Re: Debating Rocker Ratio. | ||
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Guru Newb
 
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Nothing to add yet DB. Need to set up my profile, etc
Saying hi. -Dan |
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Posted on: 2009/5/22 4:27
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| Durango_Boy | Re: Debating Rocker Ratio. | ||
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Hi Dan, glad you're on board.
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Posted on: 2009/5/22 22:59
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| wesmigletz | Re: Debating Rocker Ratio. | ||
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Senior Guru
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My stroked 327 lost 4 HP on an engine dyno when I switched from a 1.6 I/1.6 E RR Combo to a 1.6 I/1.5 E RR combo. This was with a comp 282 HR cam and 195 CC AFR heads. The engine picked-up just over 1" of vacuum from the swap.
I am currently running the 1.6/1.6 combo, but may switch to a 1.5/1.5 combo to tame the cam a bit, when I swap back to a dual plane intake. |
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Posted on: 2009/7/8 3:58
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| Durango_Boy | Re: Debating Rocker Ratio. | ||
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Elite Guru
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Yeah to me 4 HP just isn't worth it and considering I'd never see that gain down low it makes it even more absurd.
Thanks for the info everyone. |
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Posted on: 2009/7/8 9:43
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