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Re: Rocker Advice
[Re: brianlinn]
#2643800
04/10/19 08:16 PM
04/10/19 08:16 PM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,219
New York
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No matter what you buy, do the geometry yourself. No, "use lash caps" is not technical advice, it's just what people say. Get the pushrods afterward. In terms of improved breathing: if you cam is too small (and it looks mild to me) 1.6 intake rockers will help, but 1.6 exhausts will do less. If the cam is too big (certainly not yours) increased rocker ratio won't help you. Needle rocker bearings allow you to restrict rocker oil delivery somewhat. If that's not important to you, you don't need them. I prefer bronze bushings. 1.6 rockers (vs. 1.5) also increase the spring load on the pushrod, adjuster, and tappet by 6.7%: with 500 lb. rated springs at full lift, the 1.5 rocker is 750 lb. on the tappet, a 1.6 rocker will be 800 lb. This is why rockers with 1:1 ratio were popular before WWII: the cams wouldn't take the pressure, all the lift had to be built into the lobe.
Boffin Emeritus
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Re: Rocker Advice
[Re: DoubleD]
#2644396
04/12/19 12:15 PM
04/12/19 12:15 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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One quick comment that someone else may have touched on already... some of the rockers being talked about, e.g., the "original" Harland Sharps, have a very long fulcrum that biases the valve tip sweep pattern noticeably to the exhaust side of the tip. Hughes are on the long side, but not to the extreme as the standard Harland Sharps. For some folks this isn't anything they're concerned about. For others (like myself), I don't like to run things that way.
The rockers that I recall that are better suited (not saying "perfect") to being able to bolt down and not have this tendency are Crane Golds, Harland Sharp's "E" rockers (made shorter for Edelbrocks), and -- I think -- COMP's Pro Magnum steel rockers. Oh, and the old RAS stuff I believe falls into this category.
AndyF has done a lot of rocker / head mock-ups and may be willing to comment on this further. And I'd expect that Mike at B3RE can make a shaft relocation kit to help the worst offenders.
Carry on...
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