Author Topic: Dumb question 345.2 - math and geometry are not my things.  (Read 855 times)

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DuckRyder

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Dumb question 345.2 - math and geometry are not my things.
« on: August 18, 2024, 01:02:21 PM »
If a fella has a pushrod and it seems to be the proper length with respect to how far out of the rocker arms the adjusters are but needs to shim the rockers up, do the new pushrods need to automatically be longer by the same amount as the shim is thick?
Robert

jayb

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Re: Dumb question 345.2 - math and geometry are not my things.
« Reply #1 on: August 18, 2024, 07:52:26 PM »
No, it needs to be a little longer, but the exact amount will depend on the rocker ratio and the position of the adjuster ball or cup.  A good guess would be the height of the shim multiplied by 2.76/1.76, or about 1.5.  So if you are shimming the stands up .040", the pushrods needed to keep the adjusters about where they are would be .060" longer.  Of course, that additional .020" is not more than about a half a turn on the adjuster, maybe not enough to worry about...
Jay Brown
- 1969 Mach 1, Drag Week 2005 Winner NA/BB, 511" FE (10.60s @ 129); Drag Week 2007 Runner-Up PA/BB, 490" Supercharged FE (9.35 @ 151)
- 1964 Ford Galaxie, Drag Week 2009 Winner Modified NA (9.50s @ 143), 585" SOHC
- 1969 Shelby Clone, Drag Week 2015 Winner Modified NA (Average 8.98 @ 149), 585" SOHC

   

DuckRyder

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Re: Dumb question 345.2 - math and geometry are not my things.
« Reply #2 on: August 19, 2024, 06:43:33 AM »
Thanks Jay,

Glad I asked.

Its an FE with Harland Sharps so i'll use 1.5 to approximate, as noted that should get me in the ballpark.

Robert