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Whats the differance between 7.400 and 7.350 pushrods?

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Old May 21, 2005 | 11:36 AM
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Default Whats the differance between 7.400 and 7.350 pushrods?

just wondering if they make any difference in performance, strength,ect.
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Old May 21, 2005 | 11:43 AM
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7.40 is stock length. It is ideal for stock cams and unmilled heads. Many aftermarket cams have a smaller base circle than stock, which in theory would require a longer pushrod, but most racers keep the stock length pushrod to allow the pushrod to work higher in the plunger of the roller lifter (this keeps the lifter from pumping up and extends rpm range).

7.35" pushrods are .050" shorter and work well when you've milled the heads .030" or more. The shorter length keeps the valve geometry closer to stock (which is close to ideal).
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Old May 21, 2005 | 11:59 AM
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Thanks
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Old May 21, 2005 | 02:01 PM
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Pushrods are also the only way to adjust pre-load on a non adjustable valvetrain like the LS-1's. Shorter pushrods= less pre-load.
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Old May 21, 2005 | 02:39 PM
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Originally Posted by Beast96Z
Pushrods are also the only way to adjust pre-load on a non adjustable valvetrain like the LS-1's. Shorter pushrods= less pre-load.
Pushrods or shims.
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Old May 21, 2005 | 11:07 PM
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Originally Posted by Patrick G
Pushrods or shims.
Shims aren't the correct way to change pre-load. I was under the same impression till I ran the rocker off the tip of the valve. Placing shims changes the geometry of the rocker. It actually moves the rockers up from there normal location, which means they are gunna move on the tip of the valve. If they move up to much, they will fall off the tip of the valve. Always get as close as you can with the pushrod, and if you must, use a .010"-.020" shim at the most. Personally, I wouldn't go over .010".
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