push rod thickness
05-21-2007, 11:16 PM
#1
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push rod thickness I know the stockers are fine for most applications, however I've heard some high end builders mention using a bigger size than stock. So what is a good size to upgrade to in the LS1 applications, and what will fit in the stock heads? 3/8"?
05-22-2007, 04:48 AM
#3
Some of the newer heads, TFS and ETP, can benefit from the 3/8" pushrod due to the longer length required for the smaller valve angle. Crane also just introduced a 3/8" setup for their rockers including 3/8 guidplates. I read where they found the 5/16" were deflecting a considerable amount at higher RPM and spring loads and there was a loss if valve lift as a result.
05-22-2007, 08:02 AM
#4
Originally Posted by vettenuts
Crane also just introduced a 3/8" setup for their rockers including 3/8 guidplates. I read where they found the 5/16" were deflecting a considerable amount at higher RPM and spring loads and there was a loss if valve lift as a result.
05-22-2007, 09:01 AM
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Originally Posted by vettenuts
I read where they found the 5/16" were deflecting a considerable amount at higher RPM and spring loads and there was a loss if valve lift as a result.
05-22-2007, 03:54 PM
#6
Originally Posted by Ryan02SS
Is this with a stock pushrod? I just find it hard to believe that a .080" wall thickness chromemoly 5/16" pushrod is deflecting with the 130lbs + or - that it takes to keep an LS1 valvetrain stable at 6500rpms. My Smith Bro's .083" wall Pr'ds are rated for 200lbs seat and 400 open. Not doubting your word but would like to read more on it.
I think the only way one would be able to see actual data would be to:
1) Purchase a Spintron and other equipment needed to test
2) Write to Myth Busters and see if they can 'bust' this myth
05-22-2007, 11:07 PM
#7
You would be surprised what goes on with the valve train at rpm. There are some good videos of the valves during a spintron test. Maybe it was on the PAC website. On my L98 build I went with 3/8" Manton #4 pushrods.
OldStroker said that everything is a spring in the valve train. Looking at those videos he is correct. You don't want your pushrods acting like a pole vault.
OldStroker said that everything is a spring in the valve train. Looking at those videos he is correct. You don't want your pushrods acting like a pole vault.
