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 Post subject: BBC pushrod requirements
 Post Posted: Fri Feb 12, 2010 8:19 pm 
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Joined: Tue Apr 01, 2008 10:56 pm
Posts: 110
Location: Kilgore Tx [North East Tx]
Let me have your experience about pushrod requirements. This 496 BBC has 275 lb seat pressure and 735 lb open pressure at .790 net lift. Roller cam, T & D rockers, Dart 335 CNC heads. Unless I do some clearance grinding here and there a 7/16 pushrod will not clear. (slight interference at several places depending on which cylinder, casing is slightly irregular here and there, some cylinders would clear 7/16 but some won't)

So the simplest fix is 3/8 pushrods.

Is a 3/8" x .125" pushrod acceptable for this application?

Gasoline, no power adders, about 7800 RPM upper limit.

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Larry Woodfin, builder of Kinetic Art.


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 Post Posted: Sat Feb 13, 2010 12:21 pm 
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Joined: Sat Oct 21, 2006 11:41 pm
Posts: 768
Location: Morrison, Co
I would think it would be ok for your app. Not ideal, but you should be ok. I know I'm going to run 7/16" .125 in mine, but I have a tall deck block, will be running 8000+ rpms, and nitrous. My springs will be in the range of 400+ lbs on the seat, 1100+ open. So ultra-stiff pushrods are the only option for me. I'll "make" them fit no matter what. Have you thought about tapered pushrods? Manton and others make a 7/16 - 3/8 tapered that would work good in your app. My buddy in Alaska that runs a pro-mod runs those, with stupid high spring pressures and 45+lbs of boost with no issues. There is some really good pricing on them now too, as they are really common these days.

Just my 1 1/2 cents.....(can't afford the other 1/2)

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Mark Goulette
Owner/driver, Livin' the Dream Racing Dragster
Speed Kills, But It's Better Than Going Slow!!!
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 Post Posted: Sat Feb 13, 2010 3:16 pm 
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Joined: Wed Apr 19, 2006 4:11 pm
Posts: 2749
Location: Shepherdsville, KY
I run about the same seat pressure but less lift than that. I am running .120 wall 3/8" 4130 pushrod that's 9.150" long. I spin mine to 8,200 rpm. I was running a slightly shorter .080 5/16 pushrod in the same motor until a couple of years ago. Never had any trouble with either of them but switched to the 3/8 when I corrected some other issues with my motor. There's a thread on here somewhere that deals with pushrod deflection and that was a good part of the reason I went bigger.

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