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7.650 Pushrods???

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Old May 26, 2010 | 09:35 AM
  #1  
CS Vette's Avatar
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Default 7.650 Pushrods???

Adding TFS 215's to my EG cam and FAST 90 setup. Also going with YT 1.7 rockers. I ordered 7.500 pushrods but they looked to be about 1/4 inch too short. Got a pushrod length checker and came up with 7.650". With that length I could still spin the pushrod and roll the tip of the roller rocker (so I know there wasn't too much tension on either one). The rocker is tight and has no play. If I go any shorter (ie: 7.625") the rocker feels spongy on the pushrod side and I can get a very slight "tick" out of the valve side. Does it sound like I'm in the ballpark or does my pushrod sound way too long?

Here are the details just in case:
-TFS 215's ported and milled to 59cc
-PRC .660" lift springs
-Yella Terra 1.7 RR's
-LS7 lifters
-EG Monster Cam (234/240 598/608 @ 114)
-GM MLS head gaskets

Tried a few different ways of measuring pushrod length: Shane's way at Texas Speed, LS1-how-to way, and the ol' "unscrew the checker pushrod until you get no play" way. Guess I'm just looking for some confirmation. Thanks Fellas!
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Old May 26, 2010 | 01:56 PM
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Sounds long to me especially with that mill. I have 7.5's on my TFS heads at 60.5cc so you being milled more I would think you are slightly shorter....Same lifters as you BTW so no diff there. Our cams are close too (230/234) so the base circle should be close also. IDK what to tell you other than that.........

Try to pm or call TEA or Vengeance..... maybe they would be willing to advise you. They do more TFS stuff than anybody else on here....
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Old May 26, 2010 | 04:07 PM
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Have you checked the rocker wipe pattern and if so how much shim thickness was required (if any)?
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Old May 26, 2010 | 04:15 PM
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If 7.650 is the length on the checker, I believe you have to add the peload to that length.
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Old May 26, 2010 | 04:29 PM
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CS vette, check your inbox
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Old May 27, 2010 | 09:53 AM
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Wipe pattern is right on and all geometry looks correct. My inbox is empty.

My main question here is:
With the correct length pushrod, should I be able to push down on the back of the rocker (pushrod side) and create a small gap above the valve spring? Just enough to get a very slight "tick" when I push down repeatedly.

OR:
With the correct length pushrod, should the rocker be tight enough where I can not create a gap on the pushrod or valve spring side when I push down on the rocker? However, not so tight that I can not rotate the pushrod or roll the tip of the rocker (valve spring side).
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Old May 27, 2010 | 10:06 AM
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you should be able to push down on the back of the rocker and lift the tip off the valve stem, that is lifter preload. once the oil system pressurizes, that will go away.

my question is, did you add the add the required preload into your measured length? that will make your pushrod longer than what you have measured.
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