FrontEngineDragsters.Org Forum
Technical => Matt Shaff's Engine Shop => Topic started by: Mister_Fitz on May 20, 2018, 12:25:25 AM
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I have changed to shaft rockers and need to buy some new push rods.
Previous I was running 5/16" x 0.080" push rods with the stud mounted rockers without any noticeably problems.
Push rods are 6.50" long, cam is a mechanical roller with 0.735" lift and springs are 510 lbs.
Should I try to grind the heads for clearing 3/8" push rods or go with the smaller 5/16".
What do you run and have you noticed any improvements when going from 5/16" to 3/8"?
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With a short push rod like that an .080 wall 5/16ths will work perfect
also at 510 lbs open you are light on spring pressure so 5/16ths will do great
In longer push rod applications where pressures are 650-700 range a 3/8ths would be best choice if there is room but it is sort of like a test question--correct answer is Yes 3/8ths better but in many applications getting them in there can be PIA
I would feel fine with 5/16ths in your application
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Like dusterdave173 said 5/16 are fine it's also keeping weight down but you have a third choice tapered 5/16 to 3/8 if you decide that you need a stronger push rod without grinding the heads
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My Super Stock buddies run 3/8 pushrods as they claim they have much better valve train stability. These are 265 and 283’s and not high RPM engines as they cannot get the WCFB carbs to breathe good enough.
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as with tubing increasing dia with the same wall is a lot stronger less flex and push rods are the weak link changing to shaft mounted rocker you have eliminated flex at the stud and would get more flex at the push rod. and push rods do flex