Re: Breaking rockers - bad mistake
[Re: AndyF]
#2545679
09/04/18 03:03 PM
09/04/18 03:03 PM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
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master
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New York
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I'm sure about cutting the Hughes rockers - it tells you EXACTLY where they'll break. There are places in the engine where a sharp edge is a bad idea (piston dome) but harmless. Where that cut was taken is the worst possible place to remove any metal (the center of a span stressed in tension), and more so leaving a sharp negative profile with a violent change in cross-section. If you absolutely have to remove metal there, cut only to the minimum depth to assure clearance (don't be surprised if some rockers need more than others - an extrusion or casting isn't accurate from the mold down to .001"), then blend & radius the cut into the parent shape in all directions so that the original cut is invisible. I would polish it, but that's just my OCD.
Boffin Emeritus
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Re: Breaking rockers - bad mistake
[Re: moparx]
#2546106
09/05/18 12:15 PM
09/05/18 12:15 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
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Romeo MI
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I had a special end mill mad u just to clearance rockers if they needed it.. was a 1 1/2" with a 1/8" radius at the bottom.. I could do a small plunge cut in one shot
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Re: Breaking rockers - bad mistake
[Re: AndyF]
#2546150
09/05/18 01:45 PM
09/05/18 01:45 PM
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Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
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master
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Posts: 2,540
Milwaukee WI
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Fly cutter with a generous radius
"use it 'till it breaks, replace as needed"
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Re: Breaking rockers - bad mistake
[Re: AndyF]
#2546258
09/05/18 04:12 PM
09/05/18 04:12 PM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
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master
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New York
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It's not only a function of lift, but the actual length (not the rocker ratio) of the valve-side lever is X-important. A really long rocker (Gen-1 hemi exhaust) is moving almost vertically with low lift with a very short scrub path.
Boffin Emeritus
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Re: Breaking rockers - bad mistake
[Re: LaRoy Engines]
#2546437
09/05/18 11:05 PM
09/05/18 11:05 PM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
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Washington
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If you think you have to grind or cut the rocker arms, discover the real problem and fix that. STICKY THIS SENTENCE^^^^^^^^^^^^^^ /THREAD
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: Breaking rockers - bad mistake
[Re: AndyF]
#2546451
09/05/18 11:39 PM
09/05/18 11:39 PM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
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master
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Posts: 4,219
New York
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The "real problem" is apparently bad rocker arms. Way too often, they try to make a small change in an existing product (Olds V8 to Windsor, BBC to Ford L6) to save R&D, but they don't have anyone on staff competent to say "wait a minute, there are other differences...". Rocker arm geometry (not application) was settled engineering 300 years ago, they're not paying attention. Don't modify them? Throw them away? And replace them with what? Ask the manufacturer "do these fit?" What answer do you think you'll get? Is Barton, T&D, and Jesel the answer for everyone?
We have tolerated crap from even the most expensive sources far too long to expect NEVER to get a part that needs adjustment, etc.
[/rant]
Boffin Emeritus
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