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Charlie175 
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Joined: 11 Sep 2009
Location: Shenandoah, VA
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 Topic: Roller Rockers
Posted: 29 Aug 2016 at 6:24am |
How does a Roller Rocker aid in Performance (201/226 motors)?
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Charlie
'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD
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Zaddison
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Joined: 19 Sep 2013
Location: Moweaqua il.
Points: 174
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Posted: 29 Aug 2016 at 6:38am |
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At stock rpm I wouldn't think much at all however if they are high lift rockers like the murphys Ive heard like ten percent increase in power. But I'm sure it would differ from motor to motor.
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O.P.S. Heads
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Joined: 02 Jan 2013
Location: Iowa
Points: 574
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Posted: 29 Aug 2016 at 8:24pm |
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It's not the roller feature that adds power, its the change in rocker arm ratio (probably from 1.500 stock to 1.75 with the new rockers)that makes the valves travel farther (open more) in the same amount of time in crankshaft degrees. The valve leaves the seat quicker and opens farther which in general gives most engines more power. The roller tip is added so the additional friction on top of the valve stem from the more aggressive rocker arm is reduced. Be sure you have enough piston to valve clearance if changing to faster rockers. Keep in mind faster rockers add more stress to the rocker arm shaft, pushrods, and camshaft.
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Charlie175
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Posted: 30 Aug 2016 at 5:25am |
OK, that makes sense. Thank you for the explanation. These are Murphys at 1.85 ratio.
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Charlie
'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD
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WF owner
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Joined: 12 May 2013
Location: Bombay NY
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Posted: 30 Aug 2016 at 5:41am |
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How do you check valve/piston clearance? Is there a way to put something (like modeling clay) on to of the piston and turn it over slowly?
Has anyone used the roller rockers with a cam grind similar to the 175 cam?
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Carl(NWWI)
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Joined: 13 Sep 2009
Location: NW WI
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Posted: 30 Aug 2016 at 1:25pm |
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Another question, my WD is getting pretty tired and do for some new parts, will the roller rockers clear the pistons in a 226 with flat top wd pistons and a Barney cam?
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DrAllis
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Posted: 30 Aug 2016 at 3:04pm |
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No need to tear engine down. Install the new rockers and adjust valve lash. Turn engine over very slowly by hand to verify clearance is enough. Flat tops most forgiving. Open exhaust valve being kissed by a rising piston is the most probable. Make a lever tool to force opening the exhaust valve a little farther each 10 degrees or so of rotation and find the tightest spot. Measure the clearance with a dial indicator on the valve spring retainer. .060" is probably enough and more is even better.
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